draft-ietf-core-resource-directory-07.txt   draft-ietf-core-resource-directory-08.txt 
CoRE Z. Shelby CoRE Z. Shelby
Internet-Draft ARM Internet-Draft ARM
Intended status: Standards Track M. Koster Intended status: Standards Track M. Koster
Expires: September 22, 2016 SmartThings Expires: January 8, 2017 SmartThings
C. Bormann C. Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
P. van der Stok P. van der Stok
consultant consultant
March 21, 2016 July 07, 2016
CoRE Resource Directory CoRE Resource Directory
draft-ietf-core-resource-directory-07 draft-ietf-core-resource-directory-08
Abstract Abstract
In many M2M applications, direct discovery of resources is not In many M2M applications, direct discovery of resources is not
practical due to sleeping nodes, disperse networks, or networks where practical due to sleeping nodes, disperse networks, or networks where
multicast traffic is inefficient. These problems can be solved by multicast traffic is inefficient. These problems can be solved by
employing an entity called a Resource Directory (RD), which hosts employing an entity called a Resource Directory (RD), which hosts
descriptions of resources held on other servers, allowing lookups to descriptions of resources held on other servers, allowing lookups to
be performed for those resources. This document specifies the web be performed for those resources. This document specifies the web
interfaces that a Resource Directory supports in order for web interfaces that a Resource Directory supports in order for web
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 22, 2016. This Internet-Draft will expire on January 8, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Architecture and Use Cases . . . . . . . . . . . . . . . . . 5 3. Architecture and Use Cases . . . . . . . . . . . . . . . . . 5
3.1. Use Case: Cellular M2M . . . . . . . . . . . . . . . . . 6 3.1. Use Case: Cellular M2M . . . . . . . . . . . . . . . . . 6
3.2. Use Case: Home and Building Automation . . . . . . . . . 7 3.2. Use Case: Home and Building Automation . . . . . . . . . 7
3.3. Use Case: Link Catalogues . . . . . . . . . . . . . . . . 7 3.3. Use Case: Link Catalogues . . . . . . . . . . . . . . . . 7
4. Simple Directory Discovery . . . . . . . . . . . . . . . . . 8 4. Finding a Directory Server . . . . . . . . . . . . . . . . . 8
4.1. Finding a Directory Server . . . . . . . . . . . . . . . 9 4.1. Resource Directory Address Option (RDAO) . . . . . . . . 9
4.2. Third-party registration . . . . . . . . . . . . . . . . 10 5. Simple Registration . . . . . . . . . . . . . . . . . . . . . 10
5. Resource Directory Function Set . . . . . . . . . . . . . . . 10 5.1. Simple publishing to Resource Directory Server . . . . . 11
5.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 10 5.2. Third-party registration . . . . . . . . . . . . . . . . 12
5.2. Registration . . . . . . . . . . . . . . . . . . . . . . 12 6. Resource Directory Function Set . . . . . . . . . . . . . . . 12
5.3. Update . . . . . . . . . . . . . . . . . . . . . . . . . 15 6.1. Content Formats . . . . . . . . . . . . . . . . . . . . . 13
5.4. Removal . . . . . . . . . . . . . . . . . . . . . . . . . 17 6.2. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 13
5.5. Read Endpoint Links . . . . . . . . . . . . . . . . . . . 18 6.3. Registration . . . . . . . . . . . . . . . . . . . . . . 15
5.6. Update Endpoint Links . . . . . . . . . . . . . . . . . . 19 6.4. Registration Update . . . . . . . . . . . . . . . . . . . 18
6. Group Function Set . . . . . . . . . . . . . . . . . . . . . 22 6.5. Registration Removal . . . . . . . . . . . . . . . . . . 20
6.1. Register a Group . . . . . . . . . . . . . . . . . . . . 22 6.6. Read Endpoint Links . . . . . . . . . . . . . . . . . . . 21
6.2. Group Removal . . . . . . . . . . . . . . . . . . . . . . 24 6.7. Update Endpoint Links . . . . . . . . . . . . . . . . . . 22
7. RD Lookup Function Set . . . . . . . . . . . . . . . . . . . 25 7. Group Function Set . . . . . . . . . . . . . . . . . . . . . 24
8. New Link-Format Attributes . . . . . . . . . . . . . . . . . 29 7.1. Register a Group . . . . . . . . . . . . . . . . . . . . 24
8.1. Resource Instance attribute 'ins' . . . . . . . . . . . . 30 7.2. Group Removal . . . . . . . . . . . . . . . . . . . . . . 26
8.2. Export attribute 'exp' . . . . . . . . . . . . . . . . . 30 8. RD Lookup Function Set . . . . . . . . . . . . . . . . . . . 27
9. DNS-SD Mapping . . . . . . . . . . . . . . . . . . . . . . . 30 9. New Link-Format Attributes . . . . . . . . . . . . . . . . . 32
9.1. DNS-based Service discovery . . . . . . . . . . . . . . . 31 9.1. Resource Instance attribute 'ins' . . . . . . . . . . . . 32
9.2. mapping ins to <Instance> . . . . . . . . . . . . . . . . 32 9.2. Export attribute 'exp' . . . . . . . . . . . . . . . . . 33
9.3. Mapping rt to <ServiceType> . . . . . . . . . . . . . . . 32 10. DNS-SD Mapping . . . . . . . . . . . . . . . . . . . . . . . 33
9.4. Domain mapping . . . . . . . . . . . . . . . . . . . . . 33 10.1. DNS-based Service discovery . . . . . . . . . . . . . . 33
9.5. TXT Record key=value strings . . . . . . . . . . . . . . 33 10.2. mapping ins to <Instance> . . . . . . . . . . . . . . . 34
9.6. Importing resource links into DNS-SD . . . . . . . . . . 33 10.3. Mapping rt to <ServiceType> . . . . . . . . . . . . . . 35
10. Security Considerations . . . . . . . . . . . . . . . . . . . 34 10.4. Domain mapping . . . . . . . . . . . . . . . . . . . . . 35
10.1. Endpoint Identification and Authentication . . . . . . . 34 10.5. TXT Record key=value strings . . . . . . . . . . . . . . 35
10.2. Access Control . . . . . . . . . . . . . . . . . . . . . 35 10.6. Importing resource links into DNS-SD . . . . . . . . . . 36
10.3. Denial of Service Attacks . . . . . . . . . . . . . . . 35 11. Security Considerations . . . . . . . . . . . . . . . . . . . 36
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 11.1. Endpoint Identification and Authentication . . . . . . . 37
11.1. Resource Types . . . . . . . . . . . . . . . . . . . . . 35 11.2. Access Control . . . . . . . . . . . . . . . . . . . . . 37
11.2. Link Extension . . . . . . . . . . . . . . . . . . . . . 36 11.3. Denial of Service Attacks . . . . . . . . . . . . . . . 37
11.3. RD Parameter Registry . . . . . . . . . . . . . . . . . 36 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38
12. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 37 12.1. Resource Types . . . . . . . . . . . . . . . . . . . . . 38
12.1. Lighting Installation . . . . . . . . . . . . . . . . . 37 12.2. Link Extension . . . . . . . . . . . . . . . . . . . . . 38
12.1.1. Installation Characteristics . . . . . . . . . . . . 37 12.3. IPv6 ND Resource Directory Address Option . . . . . . . 38
12.1.2. RD entries . . . . . . . . . . . . . . . . . . . . . 38 12.4. RD Parameter Registry . . . . . . . . . . . . . . . . . 38
12.1.3. DNS entries . . . . . . . . . . . . . . . . . . . . 42 13. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 39
12.1.4. RD Operation . . . . . . . . . . . . . . . . . . . . 45 13.1. Lighting Installation . . . . . . . . . . . . . . . . . 39
12.2. OMA Lightweight M2M (LWM2M) Example . . . . . . . . . . 45 13.1.1. Installation Characteristics . . . . . . . . . . . . 40
12.2.1. The LWM2M Object Model . . . . . . . . . . . . . . . 46 13.1.2. RD entries . . . . . . . . . . . . . . . . . . . . . 41
12.2.2. LWM2M Register Endpoint . . . . . . . . . . . . . . 47 13.1.3. DNS entries . . . . . . . . . . . . . . . . . . . . 44
12.2.3. Alternate Base URI . . . . . . . . . . . . . . . . . 48 13.2. OMA Lightweight M2M (LWM2M) Example . . . . . . . . . . 44
12.2.4. LWM2M Update Endpoint Registration . . . . . . . . . 49 13.2.1. The LWM2M Object Model . . . . . . . . . . . . . . . 45
12.2.5. LWM2M De-Register Endpoint . . . . . . . . . . . . . 49 13.2.2. LWM2M Register Endpoint . . . . . . . . . . . . . . 46
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 49 13.2.3. Alternate Base URI . . . . . . . . . . . . . . . . . 48
14. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 49 13.2.4. LWM2M Update Endpoint Registration . . . . . . . . . 48
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 52 13.2.5. LWM2M De-Register Endpoint . . . . . . . . . . . . . 48
15.1. Normative References . . . . . . . . . . . . . . . . . . 52 14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 48
15.2. Informative References . . . . . . . . . . . . . . . . . 53 15. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 49
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
16.1. Normative References . . . . . . . . . . . . . . . . . . 52
16.2. Informative References . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
1. Introduction 1. Introduction
The work on Constrained RESTful Environments (CoRE) aims at realizing The work on Constrained RESTful Environments (CoRE) aims at realizing
the REST architecture in a suitable form for the most constrained the REST architecture in a suitable form for the most constrained
nodes (e.g., 8-bit microcontrollers with limited RAM and ROM) and nodes (e.g., 8-bit microcontrollers with limited RAM and ROM) and
networks (e.g. 6LoWPAN). CoRE is aimed at machine-to-machine (M2M) networks (e.g. 6LoWPAN). CoRE is aimed at machine-to-machine (M2M)
applications such as smart energy and building automation. applications such as smart energy and building automation.
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All groups within a domain are unique. All groups within a domain are unique.
Endpoint Endpoint
Endpoint (EP) is a term used to describe a web server or client in Endpoint (EP) is a term used to describe a web server or client in
[RFC7252]. In the context of this specification an endpoint is [RFC7252]. In the context of this specification an endpoint is
used to describe a web server that registers resources to the used to describe a web server that registers resources to the
Resource Directory. An endpoint is identified by its endpoint Resource Directory. An endpoint is identified by its endpoint
name, which is included during registration, and is unique within name, which is included during registration, and is unique within
the associated domain of the registration. the associated domain of the registration.
Commissioning Tool Commissioning Tool (CT) is a device that assists
during the installation of the network by assigning values to
parameters, naming endpoints and groups, or adapting the
installation to the needs of the applications.
3. Architecture and Use Cases 3. Architecture and Use Cases
The resource directory architecture is illustrated in Figure 1. A The resource directory architecture is illustrated in Figure 1. A
Resource Directory (RD) is used as a repository for Web Links Resource Directory (RD) is used as a repository for Web Links
[RFC5988] about resources hosted on other web servers, which are [RFC5988] about resources hosted on other web servers, which are
called endpoints (EP). An endpoint is a web server associated with a called endpoints (EP). An endpoint is a web server associated with a
scheme, IP address and port (called Context), thus a physical node scheme, IP address and port (called Context), thus a physical node
may host one or more endpoints. The RD implements a set of REST may host one or more endpoints. The RD implements a set of REST
interfaces for endpoints to register and maintain sets of Web Links interfaces for endpoints to register and maintain sets of Web Links
(called resource directory entries), and for clients to lookup (called resource directory entries), and for clients to lookup
resources from the RD or maintain groups. Endpoints themselves can resources from the RD or maintain groups. Endpoints themselves can
also act as clients. An RD can be logically segmented by the use of also act as clients. An RD can be logically segmented by the use of
Domains. The domain an endpoint is associated with can be defined by Domains. The domain an endpoint is associated with can be defined by
the RD or configured by an outside entity. This information the RD or configured by an outside entity. This information
hierarchy is shown in Figure 2. hierarchy is shown in Figure 2.
Endpoints are assumed to proactively register and maintain resource Endpoints are assumed to proactively register and maintain resource
directory entries on the RD, which are soft state and need to be directory entries on the RD, which are soft state and need to be
periodically refreshed. An endpoint is provided with interfaces to periodically refreshed. An endpoint is provided with interfaces to
register, update and remove a resource directory entry. Furthermore, register, update and remove a resource directory entry. Furthermore,
a mechanism to discover an RD using the CoRE Link Format is defined. a mechanism to discover an RD using the CoRE Link Format [RFC6690] is
It is also possible for an RD to proactively discover Web Links from defined. It is also possible for an RD to proactively discover Web
endpoints and add them as resource directory entries. A lookup Links from endpoints and add them as resource directory entries. A
interface for discovering any of the Web Links held in the RD is lookup interface for discovering any of the Web Links held in the RD
provided using the CoRE Link Format. is provided using the CoRE Link Format.
Registration Lookup, Group Registration Lookup, Group
Interface Interfaces Interface Interfaces
+----+ | | +----+ | |
| EP |---- | | | EP |---- | |
+----+ ---- | | +----+ ---- | |
--|- +------+ | --|- +------+ |
+----+ | ----| | | +--------+ +----+ | ----| | | +--------+
| EP | ---------|-----| RD |----|-----| Client | | EP | ---------|-----| RD |----|-----| Client |
+----+ | ----| | | +--------+ +----+ | ----| | | +--------+
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| EP |---- | | | EP |---- | |
+----+ +----+
Figure 1: The resource directory architecture. Figure 1: The resource directory architecture.
+------------+ +------------+
| Domain | <-- Name | Domain | <-- Name
+------------+ +------------+
| | | |
| +------------+ | +------------+
| | Group | <-- Name, IP | | Group | <-- Name, Scheme, IP, Port
| +------------+ | +------------+
| | | |
+------------+ +------------+
| Endpoint | <-- Name, Scheme, IP, Port | Endpoint | <-- Name, Scheme, IP, Port
+------------+ +------------+
| |
| |
+------------+ +------------+
| Resource | <-- Target, Parameters | Resource | <-- Target, Parameters
+------------+ +------------+
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Directory (for example EPs installed on vehicles enabling tracking of Directory (for example EPs installed on vehicles enabling tracking of
their position for fleet management purposes and monitoring their position for fleet management purposes and monitoring
environment parameters) hosted by the mobile operator or somewhere environment parameters) hosted by the mobile operator or somewhere
else in the network, periodically a description of its own else in the network, periodically a description of its own
capabilities. Due to the usual network configuration of mobile capabilities. Due to the usual network configuration of mobile
networks, the EPs attached to the mobile network may not always be networks, the EPs attached to the mobile network may not always be
efficiently reachable. Therefore, a remote server is usually used to efficiently reachable. Therefore, a remote server is usually used to
provide proxy access to the EPs. The address of each (proxy) provide proxy access to the EPs. The address of each (proxy)
endpoint on this server is included in the resource description endpoint on this server is included in the resource description
stored in the RD. The users, for example mobile applications for stored in the RD. The users, for example mobile applications for
environment monitoring, contact the RD, look-up the endpoints capable environment monitoring, contact the RD, look up the endpoints capable
of providing information about the environment using appropriate set of providing information about the environment using appropriate set
of link parameters, obtain information on how to contact them (URLs of link parameters, obtain information on how to contact them (URLs
of the proxy server) and then initiate interaction to obtain of the proxy server) and then initiate interaction to obtain
information that is finally processed, displayed on the screen and information that is finally processed, displayed on the screen and
usually stored in a database. Similarly, fleet management systems usually stored in a database. Similarly, fleet management systems
provide the appropriate link parameters to the RD to look-up for EPs provide the appropriate link parameters to the RD to look up for EPs
deployed on the vehicles the application is responsible for. deployed on the vehicles the application is responsible for.
3.2. Use Case: Home and Building Automation 3.2. Use Case: Home and Building Automation
Home and commercial building automation systems can benefit from the Home and commercial building automation systems can benefit from the
use of M2M web services. The discovery requirements of these use of M2M web services. The discovery requirements of these
applications are demanding. Home automation usually relies on run- applications are demanding. Home automation usually relies on run-
time discovery to commission the system, whereas in building time discovery to commission the system, whereas in building
automation a combination of professional commissioning and run-time automation a combination of professional commissioning and run-time
discovery is used. Both home and building automation involve peer- discovery is used. Both home and building automation involve peer-
to-peer interactions between endpoints, and involve battery-powered to-peer interactions between endpoints, and involve battery-powered
sleeping devices. sleeping devices.
The exporting of resource information to other discovery systems is The exporting of resource information to other discovery systems is
also important in these automation applications. In home automation also important in these automation applications. In home automation
there is a need to interact with other consumer electronics, which there is a need to interact with other consumer electronics, which
may already support DNS-SD, and in building automation larger may already support DNS-SD, and in building automation DNS-SD in
resource directories or DNS-SD covering multiple buildings. combination with resource directories can cover multiple buildings.
3.3. Use Case: Link Catalogues 3.3. Use Case: Link Catalogues
Resources may be shared through data brokers that have no knowledge Resources may be shared through data brokers that have no knowledge
beforehand of who is going to consume the data. Resource Directory beforehand of who is going to consume the data. Resource Directory
can be used to hold links about resources and services hosted can be used to hold links about resources and services hosted
anywhere to make them discoverable by a general class of anywhere to make them discoverable by a general class of
applications. applications.
For example, environmental and weather sensors that generate data for For example, environmental and weather sensors that generate data for
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URN encoded, simple and lossless structural transforms should URN encoded, simple and lossless structural transforms should
generally be sufficient to store external metadata in Resource generally be sufficient to store external metadata in Resource
Directories. Directories.
The additional features of Resource Directory allow domains to be The additional features of Resource Directory allow domains to be
defined to enable access to a particular set of resources from defined to enable access to a particular set of resources from
particular applications. This provides isolation and protection of particular applications. This provides isolation and protection of
sensitive data when needed. Resource groups may defined to allow sensitive data when needed. Resource groups may defined to allow
batched reads from multiple resources. batched reads from multiple resources.
4. Simple Directory Discovery 4. Finding a Directory Server
Not all endpoints hosting resources are expected to know how to
implement the Resource Directory Function Set (see Section 5) and
thus explicitly register with a Resource Directory (or other such
directory server). Instead, simple endpoints can implement the
generic Simple Directory Discovery approach described in this
section. An RD implementing this specification MUST implement Simple
Directory Discovery. However, there may be security reasons why this
form of directory discovery would be disabled.
This approach requires that the endpoint makes available the hosted
resources that it wants to be discovered, as links on its "/.well-
known/core" interface as specified in [RFC6690].
The endpoint then finds one or more IP addresses of the directory
server it wants to know about its resources as described in
Section 4.1.
An endpoint that wants to make itself discoverable occasionally sends
a POST request to the "/.well-known/core" URI of any candidate
directory server that it finds. The body of the POST request is
either
o empty, in which case the directory server is encouraged by this
POST request to perform GET requests at the requesting server's
default discovery URI.
or
o a non-empty link-format document, which indicates the specific
services that the requesting server wants to make known to the
directory server.
The directory server integrates the information it received this way
into its resource directory. It MAY make the information available
to further directories, if it can ensure that a loop does not form.
The protocol used between directories to ensure loop-free operation
is outside the scope of this document.
The following example shows an endpoint using simple resource
discovery, by simply sending a POST with its links in the body to a
directory.
EP RD
| |
| -- POST /.well-known/core "</sen/temp>..." ---> |
| |
| |
| <---- 2.01 Created ------------------------- |
| |
4.1. Finding a Directory Server
Endpoints that want to contact a directory server can obtain Endpoints that want to contact a directory server can obtain
candidate IP addresses for such servers in a number of ways. candidate IP addresses for such servers in a number of ways.
In a 6LoWPAN, good candidates can be taken from: In a 6LoWPAN, good candidates can be taken from:
o specific static configuration (e.g., anycast addresses), if any, o specific static configuration (e.g., anycast addresses), if any,
o the ABRO option of 6LoWPAN-ND [RFC6775], o the ABRO option of 6LoWPAN-ND [RFC6775],
o other ND options that happen to point to servers (such as RDNSS), o other ND options that happen to point to servers (such as RDNSS),
o DHCPv6 options that might be defined later. o DHCPv6 options that might be defined later.
o The IPv6 Neighbor Discovery Resource Directory Address Option
described in Section 4.1
In networks with more inexpensive use of multicast, the candidate IP In networks with more inexpensive use of multicast, the candidate IP
address may be a well-known multicast address, i.e. directory servers address may be a well-known multicast address, i.e. directory servers
are found by simply sending GET requests to that well-known multicast are found by simply sending GET requests to that well-known multicast
address (see Section 5.1). address (see Section 6.2).
As some of these sources are just (more or less educated) guesses, As some of these sources are just (more or less educated) guesses,
endpoints MUST make use of any error messages to very strictly rate- endpoints MUST make use of any error messages to very strictly rate-
limit requests to candidate IP addresses that don't work out. For limit requests to candidate IP addresses that don't work out. For
example, an ICMP Destination Unreachable message (and, in particular, example, an ICMP Destination Unreachable message (and, in particular,
the port unreachable code for this message) may indicate the lack of the port unreachable code for this message) may indicate the lack of
a CoAP server on the candidate host, or a CoAP error response code a CoAP server on the candidate host, or a CoAP error response code
such as 4.05 "Method Not Allowed" may indicate unwillingness of a such as 4.05 "Method Not Allowed" may indicate unwillingness of a
CoAP server to act as a directory server. CoAP server to act as a directory server.
4.2. Third-party registration 4.1. Resource Directory Address Option (RDAO)
The Resource Directory Option (RDAO) using IPv6 neighbor Discovery
(ND) carries information about the address of the Resource Directory
(RD). This information is needed when endpoints cannot discover the
Resource Directory with link-local multicast address because the
endpoint and the RD are separated by a border Router (6LBR). In many
circumstances the availability of DHCP cannot be guaranteed either
during commissioning of the network. The presence and the use of the
RD is essential during commissioning.
The RDAO format is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length = 3 | Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ RD Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fields:
Type: 38
Length: 8-bit unsigned integer. The length of
the option in units of 8 bytes.
Always 3.
Valid Lifetime: 16-bit unsigned integer. The length of
time in units of 60 seconds (relative to
the time the packet is received) that
this set of border router information is
valid. A value of all zero bits (0x0)
assumes a default value of 10,000
(~one week).
Reserved: This field is unused. It MUST be
initialized to zero by the sender and
MUST be ignored by the receiver.
RD Address: IPv6 address of the RD.
Figure 3: Resource Directory Address Option
5. Simple Registration
Not all endpoints hosting resources are expected to know how to
implement the Resource Directory Function Set (see Section 6) hence
cannot register with a Resource Directory. Instead, simple endpoints
can implement the generic Simple Directory Discovery approach
described in this section. An RD implementing this specification
MUST implement Simple Directory Discovery. However, there may be
security reasons why this form of directory discovery would be
disabled.
This approach requires that the endpoint makes available the hosted
resources that it wants to be discovered, as links on its "/.well-
known/core" interface as specified in [RFC6690].
The endpoint then finds one or more addresses of the directory server
as described in Section 4.
An endpoint can send (a selection of) hosted resources to a directory
server for publication as described in Section 5.1.
The directory server integrates the information it received this way
into its resource directory. It MAY make the information available
to further directories, if it can ensure that a loop does not form.
The protocol used between directories to ensure loop-free operation
is outside the scope of this document.
5.1. Simple publishing to Resource Directory Server
An endpoint that wants to make itself discoverable occasionally sends
a POST request to the "/.well-known/core" URI of any candidate
directory server that it finds. The body of the POST request is
empty, which triggers the resource directory server to perform GET
requests at the requesting server's default discovery URI to obtain
the link-format payload to register.
The endpoint MAY include registration parameters in the POST request
as per Section 6.3
The following example shows an endpoint using simple publishing, by
simply sending an empty POST to a resource directory.
Req:(to RD server from [ff02::1])
POST coap://rd.example.com/.well-known/core?lt=6000
Content-Format: 40
payload:
(empty payload)
Res: 2.04 Changed
(later)
Req: (from RD server to [ff02::1])
GET coap://[ff02::1]/.well-known/core
Accept: 40
Res: 2.05 Content
payload:
</sen/temp>
5.2. Third-party registration
For some applications, even Simple Directory Discovery may be too For some applications, even Simple Directory Discovery may be too
taxing for certain very constrained devices, in particular if the taxing for certain very constrained devices, in particular if the
security requirements become too onerous. security requirements become too onerous.
In a controlled environment (e.g. building control), the Resource In a controlled environment (e.g. building control), the Resource
Directory can be filled by a third device, called an installation Directory can be filled by a third device, called a commissioning
tool. The installation tool can fill the Resource Directory from a tool. The commissioning tool can fill the Resource Directory from a
database or other means. For that purpose the scheme, IP address and database or other means. For that purpose the scheme, IP address and
port of the registered device is indicated in the Context parameter port of the registered device is indicated in the Context parameter
of the registration as well. of the registration described in Section 6.3.
5. Resource Directory Function Set 6. Resource Directory Function Set
This section defines the REST interfaces between an RD and endpoints, This section defines the REST interfaces between an RD and endpoints,
which is called the Resource Directory Function Set. Although the which is called the Resource Directory Function Set. Although the
examples throughout this section assume the use of CoAP [RFC7252], examples throughout this section assume the use of CoAP [RFC7252],
these REST interfaces can also be realized using HTTP [RFC7230]. In these REST interfaces can also be realized using HTTP [RFC7230]. In
all definitions in this section, both CoAP response codes (with dot all definitions in this section, both CoAP response codes (with dot
notation) and HTTP response codes (without dot notation) are shown. notation) and HTTP response codes (without dot notation) are shown.
An RD implementing this specification MUST support the discovery, An RD implementing this specification MUST support the discovery,
registration, update, lookup, and removal interfaces defined in this registration, update, lookup, and removal interfaces defined in this
section. section.
Resource directory entries are designed to be easily exported to Resource directory entries are designed to be easily exported to
other discovery mechanisms such as DNS-SD. For that reason, other discovery mechanisms such as DNS-SD. For that reason,
parameters that would meaningfully be mapped to DNS SHOULD be limited parameters that would meaningfully be mapped to DNS SHOULD be limited
to a maximum length of 63 bytes. to a maximum length of 63 bytes.
5.1. Discovery 6.1. Content Formats
Resource Directory implementations using this specification MUST
support the application/link-format content format (ct=40).
Resource Directories implementing this specification MAY support
additional content formats.
Any additional content format supported by a Resource Directory
implementing this specification MUST have an equivalent serialization
in the application/link-format content format.
6.2. Discovery
Before an endpoint can make use of an RD, it must first know the RD's Before an endpoint can make use of an RD, it must first know the RD's
IP address, port and the path of its RD Function Set. There can be address and port, and the path of its RD Function Set. There can be
several mechanisms for discovering the RD including assuming a several mechanisms for discovering the RD including assuming a
default location (e.g. on an Edge Router in a LoWPAN), by assigning default location (e.g. on an Edge Router in a LoWPAN), by assigning
an anycast address to the RD, using DHCP, or by discovering the RD an anycast address to the RD, using DHCP, or by discovering the RD
using the CoRE Link Format (see also Section 4.1). This section using the CoRE Link Format (see also Section 4). This section
defines discovery of the RD using the well-known interface of the defines discovery of the RD using the well-known interface of the
CoRE Link Format [RFC6690] as the required mechanism. It is however CoRE Link Format [RFC6690] as the required mechanism. It is however
expected that RDs will also be discoverable via other methods expected that RDs will also be discoverable via other methods
depending on the deployment. depending on the deployment.
Discovery is performed by sending either a multicast or unicast GET Discovery of the RD function set is performed by sending either a
request to "/.well-known/core" and including a Resource Type (rt) multicast or unicast GET request to "/.well-known/core" and including
parameter [RFC6690] with the value "core.rd" in the query string. a Resource Type (rt) parameter [RFC6690] with the value "core.rd" in
Likewise, a Resource Type parameter value of "core.rd-lookup" is used the query string. Likewise, a Resource Type parameter value of
to discover the RD Lookup Function Set. Upon success, the response "core.rd-lookup" is used to discover the RD Lookup Function Set.
will contain a payload with a link format entry for each RD Upon success, the response will contain a payload with a link format
discovered, with the URL indicating the root resource of the RD. entry for each RD discovered, with the URL indicating the root
When performing multicast discovery, the multicast IP address used resource of the RD. When performing multicast discovery, the
will depend on the scope required and the multicast capabilities of multicast IP address used will depend on the scope required and the
the network. multicast capabilities of the network.
A Resource Directory MAY provide hints about the content-formats it A Resource Directory MAY provide hints about the content-formats it
supports in the links it exposes or registers, using the "ct" link supports in the links it exposes or registers, using the "ct" link
attribute, as shown in the example below. Clients MAY use these attribute, as shown in the example below. Clients MAY use these
hints to select alternate content-formats for interaction with the hints to select alternate content-formats for interaction with the
Resource Directory. Resource Directory.
HTTP does not support multicast and consequently only unicast HTTP does not support multicast and consequently only unicast
discovery can be supported using HTTP. Links to Resource Directories discovery can be supported using HTTP. Links to Resource Directories
MAY be registered in other Resource Directories, and well-known entry MAY be registered in other Resource Directories, and well-known entry
skipping to change at page 12, line 13 skipping to change at page 14, line 49
resource. resource.
Failure: 4.04 "Not Found" is returned in case no matching entry is Failure: 4.04 "Not Found" is returned in case no matching entry is
found for a unicast request. found for a unicast request.
Failure: 4.00 "Bad Request" is returned in case of a malformed Failure: 4.00 "Bad Request" is returned in case of a malformed
request for a unicast request. request for a unicast request.
Failure: No error response to a multicast request. Failure: No error response to a multicast request.
HTTP support : NO HTTP support : YES (Unicast only)
The following example shows an endpoint discovering an RD using this The following example shows an endpoint discovering an RD using this
interface, thus learning that the base RD resource is, in this interface, thus learning that the base RD resource is, in this
example, at /rd. Note that it is up to the RD to choose its base RD example, at /rd and that the content_format delivered by the server
resource, although diagnostics and debugging is facilitated by using hosting the resource is application.xml (ct=40). Note that it is up
the base paths specified here where possible. to the RD to choose its base RD resource, although diagnostics and
debugging is facilitated by using the base paths specified here where
possible.
EP RD Req: GET coap://[ff02::1]/.well-known/core?rt=core.rd*
| |
| ----- GET /.well-known/core?rt=core.rd* ------> | Res: 2.05 Content
| | </rd>;rt="core.rd";ct=40,
| | </rd-lookup>;rt="core.rd-lookup";ct=40,
| <---- 2.05 Content "</rd>;rt="core.rd" ------- | </rd-group>;rt="core.rd-group";ct=40
| |
The following example shows the way of indicating that a client may
request alternate content-formats. The Content-Format code attribute
"ct" MAY include a space-separated sequence of Content-Format codes
as specified in [RFC7252], indicating that multiple content-formats
are available. The example below shows the required ct=40
(application/link-format) indicated as well as a vendor-specific
content format (21225).
Req: GET coap://[ff02::1]/.well-known/core?rt=core.rd* Req: GET coap://[ff02::1]/.well-known/core?rt=core.rd*
Res: 2.05 Content Res: 2.05 Content
</rd>;rt="core.rd";ct="application/link-format+cbor", </rd>;rt="core.rd";ct="40 21225",
</rd-lookup>;rt="core.rd-lookup";ct="application/link-format+cbor", </rd-lookup>;rt="core.rd-lookup";ct="40 21225",
</rd-group>;rt="core.rd-group";ct="application/link-format+cbor" </rd-group>;rt="core.rd-group";ct="40 21225"
5.2. Registration 6.3. Registration
After discovering the location of an RD Function Set, an endpoint MAY After discovering the location of an RD Function Set, an endpoint MAY
register its resources using the registration interface. This register its resources using the registration interface. This
interface accepts a POST from an endpoint containing the list of interface accepts a POST from an endpoint containing the list of
resources to be added to the directory as the message payload in the resources to be added to the directory as the message payload in the
CoRE Link Format [RFC6690], JSON CoRE Link Format (application/link- CoRE Link Format [RFC6690], JSON CoRE Link Format (application/link-
format+json), or CBOR CoRE Link Format (application/link-format+cbor) format+json), or CBOR CoRE Link Format (application/link-format+cbor)
[I-D.ietf-core-links-json], along with query string parameters [I-D.ietf-core-links-json], along with query string parameters
indicating the name of the endpoint, its domain and the lifetime of indicating the name of the endpoint, its domain and the lifetime of
the registration. All parameters except the endpoint name are the registration. All parameters except the endpoint name are
optional. It is expected that other specifications will define optional. It is expected that other specifications will define
further parameters (see Section 11.3). The RD then creates a new further parameters (see Section 12.4). The RD then creates a new
resource or updates an existing resource in the RD and returns its resource or updates an existing resource in the RD and returns its
location. An endpoint MUST use that location when refreshing location. An endpoint MUST use that location when refreshing
registrations using this interface. Endpoint resources in the RD are registrations using this interface. Endpoint resources in the RD are
kept active for the period indicated by the lifetime parameter. The kept active for the period indicated by the lifetime parameter. The
endpoint is responsible for refreshing the entry within this period endpoint is responsible for refreshing the entry within this period
using either the registration or update interface. The registration using either the registration or update interface. The registration
interface MUST be implemented to be idempotent, so that registering interface MUST be implemented to be idempotent, so that registering
twice with the same endpoint parameter does not create multiple RD twice with the same endpoint parameter does not create multiple RD
entries. entries. A new registration may be created at any time to supercede
an existing registration, replacing the registration parameters and
links.
The registration request interface is specified as follows: The registration request interface is specified as follows:
Interaction: EP -> RD Interaction: EP -> RD
Method: POST Method: POST
URI Template: /{+rd}{?ep,d,et,lt,con} URI Template: /{+rd}{?ep,d,et,lt,con}
URI Template Variables: URI Template Variables:
rd := RD Function Set path (mandatory). This is the path of the rd := RD Function Set path (mandatory). This is the path of the
RD Function Set, as obtained from discovery. An RD SHOULD use RD Function Set, as obtained from discovery. An RD SHOULD use
the value "rd" for this variable whenever possible. the value "rd" for this variable whenever possible.
ep := Endpoint name (mandatory). The endpoint name is an ep := Endpoint name (mandatory). The endpoint name is an
identifier that MUST be unique within a domain. The maximum identifier that MUST be unique within a domain. The maximum
length of this parameter is 63 bytes. length of this parameter is 63 bytes.
d := Domain (optional). The domain to which this endpoint d := Domain (optional). The domain to which this endpoint
belongs. This parameter SHOULD be less than 63 bytes. belongs. The maximum length of this parameter is 63 bytes.
Optional. When this parameter is elided, the RD MAY associate When this parameter is elided, the RD MAY associate the
the endpoint with a configured default domain. The domain endpoint with a configured default domain. The domain value is
value is needed to export the endpoint to DNS-SD (see needed to export the endpoint to DNS-SD (see Section 10).
Section 9).
et := Endpoint Type (optional). The semantic type of the et := Endpoint Type (optional). The semantic type of the
endpoint. This parameter SHOULD be less than 63 bytes. endpoint. This parameter SHOULD be less than 63 bytes.
Optional.
lt := Lifetime (optional). Lifetime of the registration in lt := Lifetime (optional). Lifetime of the registration in
seconds. Range of 60-4294967295. If no lifetime is included, seconds. Range of 60-4294967295. If no lifetime is included,
a default value of 86400 (24 hours) SHOULD be assumed. a default value of 86400 (24 hours) SHOULD be assumed.
con := Context (optional). This parameter sets the scheme, con := Context (optional). This parameter sets the scheme,
address and port at which this server is available in the form address and port at which this server is available in the form
scheme://host:port. Optional. In the absence of this scheme://host:port. In the absence of this parameter the
parameter the scheme of the protocol, source IP address and scheme of the protocol, source IP address and source port of
source port of the register request are assumed. This the register request are assumed. This parameter is mandatory
parameter is mandatory when the directory is filled by a third when the directory is filled by a third party such as an
party such as an installation tool. commissioning tool.
Content-Format: application/link-format Content-Format: application/link-format
Content-Format: application/link-format+json Content-Format: application/link-format+json
Content-Format: application/link-format+cbor Content-Format: application/link-format+cbor
The following response codes are defined for this interface: The following response codes are defined for this interface:
Success: 2.01 "Created" or 201 "Created". The Location header MUST Success: 2.01 "Created" or 201 "Created". The Location header MUST
be included with the new resource entry for the endpoint. This be included with the new resource entry for the endpoint. This
Location MUST be a stable identifier generated by the RD as it is Location MUST be a stable identifier generated by the RD as it is
used for all subsequent operations on this registration. The used for all subsequent operations on this registration. The
resource returned in the Location is only for the purpose of the resource returned in the Location is for the purpose of updating
Update (POST) and Removal (DELETE), and MUST NOT implement GET or the lifetime of the registration and for maintaining the content
PUT methods. of the registered links, including updating and deleting links.
Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed
request. request.
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following example shows an endpoint with the name "node1" The following example shows an endpoint with the name "node1"
registering two resources to an RD using this interface. The registering two resources to an RD using this interface. The
resulting location /rd/4521 is just an example of an RD generated resulting location /rd/4521 is just an example of an RD generated
location. location.
EP RD
| |
| --- POST /rd?ep=node1 "</sensors..." -------> |
| |
| |
| <-- 2.01 Created Location: /rd/4521 ---------- |
| |
Req: POST coap://rd.example.com/rd?ep=node1 Req: POST coap://rd.example.com/rd?ep=node1
Content-Format: 40 Content-Format: 40
Payload: Payload:
</sensors/temp>;ct=41;rt="temperature-c";if="sensor", </sensors/temp>;ct=41;rt="temperature-c";if="sensor",
</sensors/light>;ct=41;rt="light-lux";if="sensor" </sensors/light>;ct=41;rt="light-lux";if="sensor"
Res: 2.01 Created Res: 2.01 Created
Location: /rd/4521 Location: /rd/4521
Req: POST /rd?ep=node1 HTTP/1.1 Req: POST /rd?ep=node1 HTTP/1.1
Host : example.com Host : example.com
Content-Format: application/link-format Content-Type: application/link-format
Payload: Payload:
</sensors/temp>;ct=41;rt="temperature-c";if="sensor", </sensors/temp>;ct=41;rt="temperature-c";if="sensor",
</sensors/light>;ct=41;rt="light-lux";if="sensor" </sensors/light>;ct=41;rt="light-lux";if="sensor"
Res: 201 Created Res: 201 Created
Location: /rd/4521 Location: /rd/4521
5.3. Update 6.4. Registration Update
The update interface is used by an endpoint to refresh or update its The update interface is used by an endpoint to refresh or update its
registration with an RD. To use the interface, the endpoint sends a registration with an RD. To use the interface, the endpoint sends a
POST request to the resource returned in the Location option in the POST request to the resource returned in the Location option in the
response to the first registration. An update MAY update the response to the first registration.
lifetime or context parameters if they have changed since the last
An update MAY update the lifetime or context registration parameters
"lt", "con" as in Section 6.3 ) if they have changed since the last
registration or update. Parameters that have not changed SHOULD NOT registration or update. Parameters that have not changed SHOULD NOT
be included in an update. Upon receiving an update request, the RD be included in an update. Adding parameters that have not changed
resets the timeout for that endpoint and updates the scheme, IP increases the size of the message but does not have any other
address and port of the endpoint (using the source address of the implications. Parameters MUST be included as query parameters in an
update, or the context parameter if present). update operation as in {registration}.
Upon receiving an update request, an RD MUST reset the timeout for
that endpoint and update the scheme, IP address and port of the
endpoint, using the source address of the update, or the context
("con") parameter if present. If the lifetime parameter "lt" is
included in the received update request, the RD MUST update the
lifetime of the registration and set the timeout equal to the new
lifetime.
An update MAY optionally add or replace links for the endpoint by An update MAY optionally add or replace links for the endpoint by
including those links in the payload of the update as a CoRE Link including those links in the payload of the update as a CoRE Link
Format document. Including links in an update message greatly Format document. A link is replaced only if both the target URI and
increases the load on an RD and SHOULD be done infrequently. A link relation type match.
is replaced only if both the target URI and relation type match (see
Section 10.1)
The update request interface is specified as follows: In addition to the use of POST, as described in this section, there
is an alternate way to add, replace, and delete links using PATCH as
described in Section 6.7.
The update registration request interface is specified as follows:
Interaction: EP -> RD Interaction: EP -> RD
Method: POST Method: POST
URI Template: /{+location}{?lt,con} URI Template: /{+location}{?lt,con}
URI Template Variables: URI Template Variables:
location := This is the Location path returned by the RD as a location := This is the Location path returned by the RD as a
skipping to change at page 16, line 11 skipping to change at page 19, line 11
lt := Lifetime (optional). Lifetime of the registration in lt := Lifetime (optional). Lifetime of the registration in
seconds. Range of 60-4294967295. If no lifetime is included, seconds. Range of 60-4294967295. If no lifetime is included,
a default value of 86400 (24 hours) SHOULD be assumed. a default value of 86400 (24 hours) SHOULD be assumed.
con := Context (optional). This parameter sets the scheme, con := Context (optional). This parameter sets the scheme,
address and port at which this server is available in the form address and port at which this server is available in the form
scheme://host:port. Optional. In the absence of this scheme://host:port. Optional. In the absence of this
parameter the scheme of the protocol, source IP address and parameter the scheme of the protocol, source IP address and
source port used to register are assumed. This parameter is source port used to register are assumed. This parameter is
compulsory when the directory is filled by a third party such compulsory when the directory is filled by a third party such
as an installation tool. as a commissioning tool.
Content-Format: application/link-format (optional) Content-Format: application/link-format (mandatory)
Content-Format: application/link-format+json (optional) Content-Format: application/link-format+json (optional)
Content-Format: application/link-format+cbor (optional) Content-Format: application/link-format+cbor (optional)
The following response codes are defined for this interface: The following response codes are defined for this interface:
Success: 2.04 "Changed" or 204 "No Content" if the update was Success: 2.04 "Changed" or 204 "No Content" if the update was
successfully processed. successfully processed.
skipping to change at page 16, line 38 skipping to change at page 19, line 38
exist (e.g. may have expired). exist (e.g. may have expired).
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following example shows an endpoint updating its registration at The following example shows an endpoint updating its registration at
an RD using this interface. an RD using this interface.
EP RD
| |
| --- POST /rd/4521 --------------------------> |
| |
| |
| <-- 2.04 Changed ---------------------------- |
| |
Req: POST /rd/4521 Req: POST /rd/4521
Res: 2.04 Changed Res: 2.04 Changed
5.4. Removal The following example shows an endpoint updating its registration
with a new lifetime and context, changing an existing link, and
adding a new link using this interface. With the initial
registration the client set the following values:
o lifetime (lt)=500
o context (con)=coap://local-proxy-old.example.com:5683
o resource= </sensors/temp>;ct=41;rt="foobar";if="sensor"
Req: POST /rd/4521?lt=600&con="coap://local-proxy.example.com:5683"
Content-Format: 40
Payload:
</sensors/temp>;ct=41;rt="temperature-f";if="sensor",
</sensors/door>;ct=41;rt="door";if="sensor"
Res: 2.04 Changed
6.5. Registration Removal
Although RD entries have soft state and will eventually timeout after Although RD entries have soft state and will eventually timeout after
their lifetime, an endpoint SHOULD explicitly remove its entry from their lifetime, an endpoint SHOULD explicitly remove its entry from
the RD if it knows it will no longer be available (for example on the RD if it knows it will no longer be available (for example on
shut-down). This is accomplished using a removal interface on the RD shut-down). This is accomplished using a removal interface on the RD
by performing a DELETE on the endpoint resource. by performing a DELETE on the endpoint resource.
The removal request interface is specified as follows: The removal request interface is specified as follows:
Interaction: EP -> RD Interaction: EP -> RD
skipping to change at page 17, line 44 skipping to change at page 21, line 5
exist (e.g. may have expired). exist (e.g. may have expired).
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following examples shows successful removal of the endpoint from The following examples shows successful removal of the endpoint from
the RD. the RD.
EP RD
| |
| --- DELETE /rd/4521 ------------------------> |
| |
| |
| <-- 2.02 Deleted ---------------------------- |
| |
Req: DELETE /rd/4521 Req: DELETE /rd/4521
Res: 2.02 Deleted Res: 2.02 Deleted
5.5. Read Endpoint Links 6.6. Read Endpoint Links
Some endpoints may wish to manage their links as a collection, and Some endpoints may wish to manage their links as a collection, and
may need to read the current set of links in order to determine link may need to read the current set of links in order to determine link
maintenance operations. maintenance operations.
One or more links MAY be selected by using query filtering as One or more links MAY be selected by using query filtering as
specified in [RFC6690] Section 4.1 specified in [RFC6690] Section 4.1
The read request interface is specified as follows: The read request interface is specified as follows:
skipping to change at page 19, line 7 skipping to change at page 22, line 7
Failure: 4.04 "Not Found" or 404 "Not Found". Registration does not Failure: 4.04 "Not Found" or 404 "Not Found". Registration does not
exist (e.g. may have expired). exist (e.g. may have expired).
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following examples show successful read of the endpoint links The following examples show successful read of the endpoint links
from the RD. from the RD.
EP RD
| |
| --- GET /rd/4521 ------------------------> |
| |
| |
| <-- 2.05 Content </sensors... ---------------- |
| |
Req: GET /rd/4521 Req: GET /rd/4521
Res: 2.01 Content Res: 2.01 Content
Payload: Payload:
</sensors/temp>;ct=41;rt="temperature-c";if="sensor", </sensors/temp>;ct=41;rt="temperature-c";if="sensor",
</sensors/light>;ct=41;rt="light-lux";if="sensor" </sensors/light>;ct=41;rt="light-lux";if="sensor"
5.6. Update Endpoint Links 6.7. Update Endpoint Links
[This section will be removed before or as a result of a working- [This section will be removed before or as a result of a working-
group last-call if the PATCH methods do not achieve the same level of group last-call if the PATCH methods do not achieve the same level of
consensus as the present document.] consensus as the present document.]
A PATCH update adds, removes or changes links for the endpoint by A PATCH update adds, removes or changes links for the endpoint by
including link update information in the payload of the update as a including link update information in the payload of the update as a
merge-patch+json format [RFC7396] document. merge-patch+json format [RFC7396] document.
One or more links are selected for update by using query filtering as One or more links are selected for update by using query filtering as
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Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following examples show an endpoint adding </sensors/humid>, The following examples show an endpoint adding </sensors/humid>,
modifying </sensors/temp>, and removing </sensors/light> links in RD modifying </sensors/temp>, and removing </sensors/light> links in RD
using the Update Endpoint Links function. using the Update Endpoint Links function.
The following example shows an EP adding the link </sensors/ The following example shows an EP adding the link </sensors/
humid>;ct=41;rt="humidity-s";if="sensor" to the collection of links humid>;ct=41;rt="humid-s";if="sensor" to the collection of links at
at the location /rd/4521. the location /rd/4521.
EP RD
| |
| --- PATCH /rd/4521---------------------------> |
| |
| |
| <-- 2.04 Changed ---------------------------- |
| |
Req: PATCH /rd/4521 Req: PATCH /rd/4521
Payload: Payload:
[{"href":"/sensors/humid","ct": 41, "rt": "humidity-s", "if": "sensor"}] [{"href":"/sensors/humid","ct": 41, "rt": "humid-s", "if": "sensor"}]
Content-Format: Content-Format:
application/merge-patch+json application/merge-patch+json
Res: 2.04 Changed Res: 2.04 Changed
The following example shows an EP modifying all links at the location The following example shows an EP modifying all links at the location
/rd/4521 which are identified by href="/sensors/temp", from the /rd/4521 which are identified by href="/sensors/temp", from the
initial link-value of </sensors/temp>;rt="temperature" to the new initial link-value of </sensors/temp>;rt="temperature" to the new
link-value </sensors/temp>;rt="temperature-c";if="sensor" by changing link-value </sensors/temp>;rt="temperature-c";if="sensor" by changing
the value of the link attribute "rt" and adding the link attribute the value of the link attribute "rt" and adding the link attribute
if="sensor" using the PATCH operation with the supplied merge- if="sensor" using the PATCH operation with the supplied merge-
patch+json document payload. patch+json document payload.
EP RD
| |
| --- PATCH /rd/4521?href="/sensors/temp" ----> |
| |
| |
| <-- 2.04 Changed ---------------------------- |
| |
Req: PATCH /rd/4521?href="/sensors/temp" Req: PATCH /rd/4521?href="/sensors/temp"
Payload: Payload:
{"rt": "temperature-c", "if": "sensor"}, {"rt": "temperature-c", "if": "sensor"},
Content-Format: Content-Format:
application/merge-patch+json application/merge-patch+json
Res: 2.04 Changed Res: 2.04 Changed
This example shows an EP removing all links at the location /rd/4521 This example shows an EP removing all links at the location /rd/4521
which are identified by href="/sensors/light". which are identified by href="/sensors/light".
EP RD
| |
| --- PATCH /rd/4521?href="/sensors/light" ----> |
| |
| |
| <-- 2.04 Changed ---------------------------- |
| |
Req: PATCH /rd/4521?href="/sensors/light" Req: PATCH /rd/4521?href="/sensors/light"
Payload: Payload:
{null} {null}
Content-Format: Content-Format:
application/merge-patch+json application/merge-patch+json
Res: 2.04 Changed Res: 2.04 Changed
6. Group Function Set 7. Group Function Set
This section defines a function set for the creation of groups of This section defines a function set for the creation of groups of
endpoints for the purpose of managing and looking up endpoints for endpoints for the purpose of managing and looking up endpoints for
group operations. The group function set is similar to the resource group operations. The group function set is similar to the resource
directory function set, in that a group may be created or removed. directory function set, in that a group may be created or removed.
However unlike an endpoint entry, a group entry consists of a list of However unlike an endpoint entry, a group entry consists of a list of
endpoints and does not have a lifetime associated with it. In order endpoints and does not have a lifetime associated with it. In order
to make use of multicast requests with CoAP, a group MAY have a to make use of multicast requests with CoAP, a group MAY have a
multicast address associated with it. multicast address associated with it.
6.1. Register a Group 7.1. Register a Group
In order to create a group, a management entity used to configure In order to create a group, a commissioning tool (CT) used to
groups, makes a request to the RD indicating the name of the group to configure groups, makes a request to the RD indicating the name of
create (or update), optionally the domain the group belongs to, and the group to create (or update), optionally the domain the group
optionally the multicast address of the group. The registration belongs to, and optionally the multicast address of the group. The
message includes the list of endpoints that belong to that group. If registration message includes the list of endpoints that belong to
an endpoint has already registered with the RD, the RD attempts to that group.
use the context of the endpoint from its RD endpoint entry. If the
client registering the group knows the endpoint has already All the endpoints in the group MUST be registered with the RD before
registered, then it MAY send a blank target URI for that endpoint registering a group. If an endpoint is not yet registered to the RD
link when registering the group. Configuration of the endpoints before registering the group, the registration message returns an
themselves is out of scope of this specification. Such an interface error. The RD sends a blank target URI for every endpoint link when
for managing the group membership of an endpoint has been defined in registering the group.
[RFC7390].
Configuration of the endpoints themselves is out of scope of this
specification. Such an interface for managing the group membership
of an endpoint has been defined in [RFC7390].
The registration request interface is specified as follows: The registration request interface is specified as follows:
Interaction: Manager -> RD Interaction: CT -> RD
Method: POST Method: POST
URI Template: /{+rd-group}{?gp,d,con} URI Template: /{+rd-group}{?gp,d,con}
URI Template Variables: URI Template Variables:
rd-group := RD Group Function Set path (mandatory). This is the rd-group := RD Group Function Set path (mandatory). This is the
path of the RD Group Function Set. An RD SHOULD use the value path of the RD Group Function Set. An RD SHOULD use the value
"rd-group" for this variable whenever possible. "rd-group" for this variable whenever possible.
gp := Group Name (mandatory). The name of the group to be gp := Group Name (mandatory). The name of the group to be
created or replaced, unique within that domain. The maximum created or replaced, unique within that domain. The maximum
length of this parameter is 63 bytes. length of this parameter is 63 bytes.
d := Domain (optional). The domain to which this group belongs. d := Domain (optional). The domain to which this group belongs.
The maximum length of this parameter is 63 bytes. Optional. The maximum length of this parameter is 63 bytes. Optional.
When this parameter is elided, the RD MAY associate the When this parameter is elided, the RD MAY associate the
endpoint with a configured default domain. The domain value is endpoint with a configured default domain. The domain value is
needed to export the endpoint to DNS-SD (see Section 9) needed to export the endpoint to DNS-SD (see Section 10)
con := Context (optional). This parameter is used to set the IP con := Context (optional). This parameter is used to set the IP
multicast address at which this server is available in the form multicast address at which this server is available in the form
scheme://multicast-address:port. Optional. In the absence of scheme://multicast-address:port. Optional. In the absence of
this parameter no multicast address is configured. This this parameter no multicast address is configured. This
parameter is compulsory when the directory is filled by an parameter is compulsory when the directory is filled by a
installation tool. commissioning tool.
Content-Format: application/link-format Content-Format: application/link-format
Content-Format: application/link-format+json Content-Format: application/link-format+json
Content-Format: application/link-format+cbor Content-Format: application/link-format+cbor
The following response codes are defined for this interface: The following response codes are defined for this interface:
Success: 2.01 "Created" or 201 "Created". The Location header MUST Success: 2.01 "Created" or 201 "Created". The Location header MUST
be included with the new group entry. This Location MUST be a be included with the new group entry. This Location MUST be a
stable identifier generated by the RD as it is used for delete stable identifier generated by the RD as it is used for delete
operations on this registration. operations on this registration.
Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed
request. request.
Failure: 4.04 "Not Found" or 404 "Not Found". An Endpoint is not
registered in the RD (e.g. may have expired).
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following example shows an EP registering a group with the name The following example shows an EP registering a group with the name
"lights" which has two endpoints to an RD using this interface. The "lights" which has two endpoints to an RD using this interface. The
resulting location /rd-group/12 is just an example of an RD generated resulting location /rd-group/12 is just an example of an RD generated
group location. group location.
EP RD
| |
| - POST /rd-group?gp=lights "<>;ep=node1..." --> |
| |
| |
| <---- 2.01 Created Location: /rd-group/12 ---- |
| |
Req: POST coap://rd.example.com/rd-group?gp=lights Req: POST coap://rd.example.com/rd-group?gp=lights
Content-Format: 40
Payload: Payload:
<>;ep="node1", <>;ep="node1",
<>;ep="node2" <>;ep="node2"
Res: 2.01 Created Res: 2.01 Created
Location: /rd-group/12 Location: /rd-group/12
Req: POST /rd-group?gp=lights HTTP/1.1 Req: POST /rd-group?gp=lights HTTP/1.1
Host: example.com Host: example.com
Accept: application/link-format Content-Type: application/link-format
Payload: Payload:
<>;ep="node1", <>;ep="node1",
<>;ep="node2" <>;ep="node2"
Res: 201 Created Res: 201 Created
Location: /rd-group/12 Location: /rd-group/12
6.2. Group Removal 7.2. Group Removal
A group can be removed simply by sending a removal message to the A group can be removed simply by sending a removal message to the
location returned when registering the group. Removing a group MUST location returned when registering the group. Removing a group MUST
NOT remove the endpoints of the group from the RD. NOT remove the endpoints of the group from the RD.
The removal request interface is specified as follows: The removal request interface is specified as follows:
Interaction: Manager -> RD Interaction: CT -> RD
Method: DELETE Method: DELETE
URI Template: /{+location} URI Template: /{+location}
URI Template Variables: URI Template Variables:
location := This is the Location path returned by the RD as a location := This is the Location path returned by the RD as a
result of a successful group registration. result of a successful group registration.
skipping to change at page 25, line 25 skipping to change at page 27, line 33
Failure: 4.04 "Not Found" or 404 "Not Found". Group does not exist. Failure: 4.04 "Not Found" or 404 "Not Found". Group does not exist.
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The following examples shows successful removal of the group from the The following examples shows successful removal of the group from the
RD. RD.
EP RD
| |
| --- DELETE /rd-group/412 -------------------> |
| |
| |
| <-- 2.02 Deleted ---------------------------- |
| |
Req: DELETE /rd-group/12 Req: DELETE /rd-group/12
Res: 2.02 Deleted Res: 2.02 Deleted
7. RD Lookup Function Set 8. RD Lookup Function Set
In order for an RD to be used for discovering resources registered In order for an RD to be used for discovering resources registered
with it, a lookup interface can be provided using this function set. with it, a lookup interface can be provided using this function set.
This lookup interface is defined as a default, and it is assumed that This lookup interface is defined as a default, and it is assumed that
RDs may also support lookups to return resource descriptions in RDs may also support lookups to return resource descriptions in
alternative formats (e.g. Atom or HTML Link) or using more advanced alternative formats (e.g. Atom or HTML Link) or using more advanced
interfaces (e.g. supporting context or semantic based lookup). interfaces (e.g. supporting context or semantic based lookup).
This function set allows lookups for domains, groups, endpoints and This function set allows lookups for domains, groups, endpoints and
resources using attributes defined in the RD Function Set and for use resources using attributes defined in the RD Function Set and for use
with the CoRE Link Format. The result of a lookup request is the with the CoRE Link Format. The result of a lookup request is the
list of links (if any) corresponding to the type of lookup. Using list of links (if any) corresponding to the type of lookup. Thus, a
the Accept Option, the requester can control whether this list is domain lookup MUST return a list of domains, a group lookup MUST
returned in CoRE Link Format ("application/link-format", default) or return a list of groups, an endpoint lookup MUST return a list of
its alternate content-formats ("application/link-format+json" or endpoints and a resource lookup MUST return a list of links to
"application/link-format+cbor"). resources.
Each endpoint and resource lookup result returns respectively the
scheme (IP address and port) followed by the path part of the URI of
every endpoint and resource inside angle brackets ("<>") and followed
by the other parameters.
The target of these links SHOULD be the actual location of the The target of these links SHOULD be the actual location of the
domain, endpoint or resource, but MAY be an intermediate proxy e.g. domain, endpoint or resource, but MAY be an intermediate proxy e.g.
in the case of an HTTP lookup interface for CoAP endpoints. Multiple in the case of an HTTP lookup interface for CoAP endpoints.
query parameters MAY be included in a lookup, all included parameters
MUST match for a resource to be returned. The character '*' MAY be The domain lookup returns every lookup domain with a "/rd" value
included at the end of a parameter value as a wildcard operator. encapsulated within angle brackets.
In case that a group does not implement any multicast address, the
group lookup returns every group lookup with a "/rd-group" value
encapsulated within angle brackets. Otherwise, the group lookup
returns the multicast address of the group inside angle brackets.
Using the Accept Option, the requester can control whether this list
is returned in CoRE Link Format ("application/link-format", default)
or its alternate content-formats ("application/link-format+json" or
"application/link-format+cbor").
The page and count parameters are used to obtain lookup results in
specified increments using pagination, where count specifies how many
links to return and page specifies which subset of links organized in
sequential pages , each containing 'count' links, starting with link
zero and page zero. Thus, specifying count of 10 and page of 0 will
return the first 10 links in the result set (links 0-9). Count = 10
and page = 1 will return the next 'page' containing links 10-19, and
so on.
Multiple query parameters MAY be included in a lookup, all included
parameters MUST match for a resource to be returned. The
character'*' MAY be included at the end of a parameter value as a
wildcard operator.
The rd-lookup interface MAY use any set of query parameters to match
the registered attributes and relations. In addition, this interface
MAY be used with queries that specify domains, endpoints, and groups.
For example, a domain lookup filtering on groups would return a list
of domains that contain the specified groups. An endpoint lookup
filtering on groups would return a list of endpoints that are in the
specified groups.
The lookup interface is specified as follows: The lookup interface is specified as follows:
Interaction: Client -> RD Interaction: Client -> RD
Method: GET Method: GET
URI Template: /{+rd-lookup-base}/{lookup- URI Template: /{+rd-lookup-base}/{lookup-
type}{?d,ep,gp,et,rt,page,count,resource-param} type}{?d,ep,gp,et,rt,page,count,resource-param}
URI Template Variables: URI Template Variables:
rd-lookup-base := RD Lookup Function Set path (mandatory). This rd-lookup-base := RD Lookup Function Set path (mandatory). This
is the path of the RD Lookup Function Set. An RD SHOULD use the is the path of the RD Lookup Function Set. An RD SHOULD use the
value "rd-lookup" for this variable whenever possible. value "rd-lookup" for this variable whenever possible.
Content-Format: application/link-format (optional)
Content-Format: application/link-format+json (optional)
Content-Format: application/link-format+cbor (optional)
lookup-type := ("d", "ep", "res", "gp") (mandatory) This variable lookup-type := ("d", "ep", "res", "gp") (mandatory) This variable
is used to select the kind of lookup to perform (domain, is used to select the kind of lookup to perform (domain,
endpoint, resource, or group). endpoint, resource, or group).
ep := Endpoint name (optional). Used for endpoint, group and ep := Endpoint name (optional). Used for endpoint, group and
resource lookups. resource lookups.
d := Domain (optional). Used for domain, group, endpoint and d := Domain (optional). Used for domain, group, endpoint and
resource lookups. resource lookups.
res := resource (optional). Used for domain, group, endpoint and
resource lookups.
gp := Group name (optional). Used for endpoint, group and
resource lookups.
page := Page (optional). Parameter can not be used without the page := Page (optional). Parameter can not be used without the
count parameter. Results are returned from result set in pages count parameter. Results are returned from result set in pages
that contains 'count' results starting from index (page * that contain 'count' links starting from index (page * count).
count). Page numbering starts with zero.
count := Count (optional). Number of results is limited to this count := Count (optional). Number of results is limited to this
parameter value. If the parameter is not present, then an RD parameter value. If the page parameter is also present, the
implementation specific default value SHOULD be used. response MUST only include 'count' links starting with the
(page * count) link in the result set from the query. If the
count parameter is not present, then the response MUST return
all matching links in the result set. Link numbering starts
with zero.
rt := Resource type (optional). Used for group, endpoint and rt := Resource type (optional). Used for group, endpoint and
resource lookups. resource lookups.
et := Endpoint type (optional). Used for group, endpoint and et := Endpoint type (optional). Used for group, endpoint and
resource lookups. resource lookups.
resource-param := Link attribute parameters (optional). Any link resource-param := Link attribute parameters (optional). Any link
attribute as defined in Section 4.1 of [RFC6690], used for attribute as defined in Section 4.1 of [RFC6690], used for
resource lookups. resource lookups.
Content-Format: application/link-format (optional)
Content-Format: application/link-format+json (optional)
Content-Format: application/link-format+cbor (optional)
The following responses codes are defined for this interface: The following responses codes are defined for this interface:
Success: 2.05 "Content" or 200 "OK" with an "application/link- Success: 2.05 "Content" or 200 "OK" with an "application/link-
format", "application/link-format+cbor", or "application/link- format", "application/link-format+cbor", or "application/link-
format+json" payload containing matching entries for the lookup. format+json" payload containing matching entries for the lookup.
Failure: 4.04 "Not Found" or 404 "Not Found" in case no matching Failure: 4.04 "Not Found" or 404 "Not Found" in case no matching
entry is found for a unicast request. entry is found for a unicast request.
Failure: No error response to a multicast request. Failure: No error response to a multicast request.
skipping to change at page 27, line 36 skipping to change at page 30, line 36
Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed Failure: 4.00 "Bad Request" or 400 "Bad Request". Malformed
request. request.
Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable". Failure: 5.03 "Service Unavailable" or 503 "Service Unavailable".
Service could not perform the operation. Service could not perform the operation.
HTTP support: YES HTTP support: YES
The examples in this section assume a CoAP host with IP address The examples in this section assume a CoAP host with IP address
FDFD::123 and a default CoAP port 61616. HTTP hosts are possible and FDFD::123 and a default CoAP port 61616. HTTP hosts are possible and
do not change the nature of the examples. The following example do not change the nature of the examples.\
shows a client performing a resource lookup:
Client RD The following example shows a client performing a resource lookup:
| |
| ----- GET /rd-lookup/res?rt=temperature -----------------> |
| |
| |
| <-- 2.05 Content <coap://[FDFD::123]:61616/temp>;--------- |
| rt="temperature" -------- |
| |
Req: GET /rd-lookup/res?rt=temperature Req: GET /rd-lookup/res?rt=temperature
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::123]:61616/temp>;rt="temperature" <coap://[FDFD::123]:61616/temp>;rt="temperature"
The following example shows a client performing an endpoint type The following example shows a client performing an endpoint type
lookup: lookup:
Client RD
| |
| ----- GET /rd-lookup/ep?et=power-node --------------------> |
| |
| |
| <-- 2.05 Content <coap://[FDFD::123]:61616>;ep="node5" ---- |
| |
Req: GET /rd-lookup/ep?et=power-node Req: GET /rd-lookup/ep?et=power-node
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::123]:61616>;ep="node5", <coap://[FDFD::123]:61616>;ep="node5",
<coap://[FDFD::123]:61616>;ep="node7" <coap://[FDFD::123]:61616>;ep="node7"
The following example shows a client performing a domain lookup: The following example shows a client performing a domain lookup:
Client RD
| |
| ----- GET /rd-lookup/d ----------------------------------> |
| |
| |
| <-- 2.05 Content </rd>;d=domain1,</rd>;d=domain2 ---------- |
| |
Req: GET /rd-lookup/d Req: GET /rd-lookup/d
Res: 2.05 Content Res: 2.05 Content
</rd>;d="domain1", <>;d="domain1",
</rd>;d="domain2" <>;d="domain2"
The following example shows a client performing a group lookup for The following example shows a client performing a group lookup for
all groups: all groups:
Client RD
| |
| ----- GET /rd-lookup/gp ---------------------------------> |
| |
| |
| <-- 2.05 Content </rd-group/12>;gp="lights1"; ------------- |
| d="example.com" ------------- |
| |
Req: GET /rd-lookup/gp Req: GET /rd-lookup/gp
Res: 2.05 Content Res: 2.05 Content
</rd-group/12>;gp="lights1";d="example.com" <>;gp="lights1";d="example.com"
<>;gp="lights2";d="ecample.com"
The following example shows a client performing a lookup for all The following example shows a client performing a lookup for all
endpoints in a particular group: endpoints in a particular group:
Client RD
| |
| ----- GET /rd-lookup/ep?gp=lights1-----------------------> |
| |
| |
| <-- 2.05 Content <coap://[FDFD::123]:61616>;ep="node1" ---- |
| |
Req: GET /rd-lookup/ep?gp=lights1 Req: GET /rd-lookup/ep?gp=lights1
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::123]:61616>;ep="node1", <coap://[FDFD::123]:61616>;ep="node1",
<coap://[FDFD::123]:61616>;ep="node2", <coap://[FDFD::123]:61616>;ep="node2"
The following example shows a client performing a lookup for all The following example shows a client performing a lookup for all
groups an endpoint belongs to: groups an endpoint belongs to:
Client RD
| |
| ----- GET /rd-lookup/gp?ep=node1 -----------------------> |
| |
| |
|< 2.05 Content <coap://[FDFD::123]:61616>;gp="lights1"; -- |
| ep="node1" ------ |
| |
Req: GET /rd-lookup/gp?ep=node1 Req: GET /rd-lookup/gp?ep=node1
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::123]:61616>;gp="lights1";ep="node1", <>;gp="lights1"
8. New Link-Format Attributes The following example shows a client performing a paginated lookup
Req: GET /rd-lookup/res?page=0&count=5
Res: 2.05 Content
<coap://[FDFD::123]:61616/res/0>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/1>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/2>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/3>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/4>;rt=sensor;ct=60
Req: GET /rd-lookup/res?page=1&count=5
Res: 2.05 Content
<coap://[FDFD::123]:61616/res/5>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/6>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/7>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/8>;rt=sensor;ct=60
<coap://[FDFD::123]:61616/res/9>;rt=sensor;ct=60
9. New Link-Format Attributes
When using the CoRE Link Format to describe resources being When using the CoRE Link Format to describe resources being
discovered by or posted to a resource directory service, additional discovered by or posted to a resource directory service, additional
information about those resources is useful. This specification information about those resources is useful. This specification
defines the following new attributes for use in the CoRE Link Format defines the following new attributes for use in the CoRE Link Format
[RFC6690]: [RFC6690]:
link-extension = ( "ins" "=" quoted-string ) ; Max 63 bytes link-extension = ( "ins" "=" quoted-string ) ; Max 63 bytes
link-extension = ( "exp" ) link-extension = ( "exp" )
8.1. Resource Instance attribute 'ins' 9.1. Resource Instance attribute 'ins'
The Resource Instance "ins" attribute is an identifier for this The Resource Instance "ins" attribute is an identifier for this
resource, which makes it possible to distinguish it from other resource, which makes it possible to distinguish it from other
similar resources. This attribute is similar in use to the similar resources. This attribute is similar in use to the
<Instance> portion of a DNS-SD record (see Section 9.1, and SHOULD be <Instance> portion of a DNS-SD record (see Section 10.1, and SHOULD
unique across resources with the same Resource Type attribute in the be unique across resources with the same Resource Type attribute in
domain it is used. A Resource Instance might be a descriptive string the domain it is used. A Resource Instance might be a descriptive
like "Ceiling Light, Room 3", a short ID like "AF39" or a unique UUID string like "Ceiling Light, Room 3", a short ID like "AF39" or a
or iNumber. This attribute is used by a Resource Directory to unique UUID or iNumber. This attribute is used by a Resource
distinguish between multiple instances of the same resource type Directory to distinguish between multiple instances of the same
within the directory. resource type within the directory.
This attribute MUST be no more than 63 bytes in length. The resource This attribute MUST be no more than 63 bytes in length. The resource
identifier attribute MUST NOT appear more than once in a link identifier attribute MUST NOT appear more than once in a link
description. description. This attribute MAY be used as a query parameter in the
RD Lookup Function Set defined in Section 7.
8.2. Export attribute 'exp' 9.2. Export attribute 'exp'
The Export "exp" attribute is used as a flag to indicate that a link The Export "exp" attribute is used as a flag to indicate that a link
description MAY be exported by a resource directory to external description MAY be exported by a resource directory to external
directories. directories.
The CoRE Link Format is used for many purposes between CoAP The CoRE Link Format is used for many purposes between CoAP
endpoints. Some are useful mainly locally, for example checking the endpoints. Some are useful mainly locally, for example checking the
observability of a resource before accessing it, determining the size observability of a resource before accessing it, determining the size
of a resource, or traversing dynamic resource structures. However, of a resource, or traversing dynamic resource structures. However,
other links are very useful to be exported to other directories, for other links are very useful to be exported to other directories, for
example the entry point resource to a functional service. example the entry point resource to a functional service. This
attribute MAY be used as a query parameter in the RD Lookup Function
Set defined in Section 7.
9. DNS-SD Mapping 10. DNS-SD Mapping
CoRE Resource Discovery is intended to support fine-grained discovery CoRE Resource Discovery is intended to support fine-grained discovery
of hosted resources, their attributes, and possibly other resource of hosted resources, their attributes, and possibly other resource
relations [RFC6690]. In contrast, service discovery generally refers relations [RFC6690]. In contrast, service discovery generally refers
to a coarse-grained resolution of an endpoint's IP address, port to a coarse-grained resolution of an endpoint's IP address, port
number, and protocol. number, and protocol.
Resource and service discovery are complementary in the case of large Resource and service discovery are complementary in the case of large
networks, where the latter can facilitate scaling. This document networks, where the latter can facilitate scaling. This document
defines a mapping between CoRE Link Format attributes and DNS-Based defines a mapping between CoRE Link Format attributes and DNS-Based
Service Discovery [RFC6763] fields that permits discovery of CoAP Service Discovery [RFC6763] fields that permits discovery of CoAP
services by either method. services by either method.
9.1. DNS-based Service discovery 10.1. DNS-based Service discovery
DNS-Based Service Discovery (DNS-SD) defines a conventional method of DNS-Based Service Discovery (DNS-SD) defines a conventional method of
configuring DNS PTR, SRV, and TXT resource records to facilitate configuring DNS PTR, SRV, and TXT resource records to facilitate
discovery of services (such as CoAP servers in a subdomain) using the discovery of services (such as CoAP servers in a subdomain) using the
existing DNS infrastructure. This section gives a brief overview of existing DNS infrastructure. This section gives a brief overview of
DNS-SD; see [RFC6763] for a detailed specification. DNS-SD; see [RFC6763] for a detailed specification.
DNS-SD service names are limited to 255 octets and are of the form: DNS-SD service names are limited to 255 octets and are of the form:
Service Name = <Instance>.<ServiceType>.<Domain>. Service Name = <Instance>.<ServiceType>.<Domain>.
skipping to change at page 32, line 5 skipping to change at page 34, line 34
where a service name identifies a particular resource, the path part where a service name identifies a particular resource, the path part
of the URI must be carried in a corresponding TXT record. of the URI must be carried in a corresponding TXT record.
A DNS TXT record is in practice limited to a few hundred octets in A DNS TXT record is in practice limited to a few hundred octets in
length, which is indicated in the resource record header in the DNS length, which is indicated in the resource record header in the DNS
response message. The data consists of one or more strings response message. The data consists of one or more strings
comprising a key=value pair. By convention, the first pair is comprising a key=value pair. By convention, the first pair is
txtver=<number> (to support different versions of a service txtver=<number> (to support different versions of a service
description). description).
9.2. mapping ins to <Instance> 10.2. mapping ins to <Instance>
The Resource Instance "ins" attribute maps to the <Instance> part of The Resource Instance "ins" attribute maps to the <Instance> part of
a DNS-SD service name. It is stored directly in the DNS as a single a DNS-SD service name. It is stored directly in the DNS as a single
DNS label of canonical precomposed UTF-8 [RFC3629] "Net-Unicode" DNS label of canonical precomposed UTF-8 [RFC3629] "Net-Unicode"
(Unicode Normalization Form C) [RFC5198] text. However, to the (Unicode Normalization Form C) [RFC5198] text. However, to the
extent that the "ins" attribute may be chosen to match the DNS host extent that the "ins" attribute may be chosen to match the DNS host
name of a service, it SHOULD use the syntax defined in Section 3.5 of name of a service, it SHOULD use the syntax defined in Section 3.5 of
[RFC1034] and Section 2.1 of [RFC1123]. [RFC1034] and Section 2.1 of [RFC1123].
The <Instance> part of the name of a service being offered on the The <Instance> part of the name of a service being offered on the
skipping to change at page 32, line 30 skipping to change at page 35, line 10
or service to be accessed in many cases without any manual or service to be accessed in many cases without any manual
configuration at all. The default name should be short and configuration at all. The default name should be short and
descriptive, and MAY include a collision-resistant substring such as descriptive, and MAY include a collision-resistant substring such as
the lower bits of the device's MAC address, serial number, the lower bits of the device's MAC address, serial number,
fingerprint, or other identifier in an attempt to make the name fingerprint, or other identifier in an attempt to make the name
relatively unique. relatively unique.
DNS labels are currently limited to 63 octets in length and the DNS labels are currently limited to 63 octets in length and the
entire service name may not exceed 255 octets. entire service name may not exceed 255 octets.
9.3. Mapping rt to <ServiceType> 10.3. Mapping rt to <ServiceType>
The resource type "rt" attribute is mapped into the <ServiceType> The resource type "rt" attribute is mapped into the <ServiceType>
part of a DNS-SD service name and SHOULD conform to the reg-rel-type part of a DNS-SD service name and SHOULD conform to the reg-rel-type
production of the Link Format defined in Section 2 of [RFC6690]. The production of the Link Format defined in Section 2 of [RFC6690]. The
"rt" attribute MUST be composed of at least a single Net-Unicode text "rt" attribute MUST be composed of at least a single Net-Unicode text
string, without underscore '_' or period '.' and limited to 15 octets string, without underscore '_' or period '.' and limited to 15 octets
in length, which represents the application protocol name. This in length, which represents the application protocol name. This
string is mapped to the DNS-SD <ServiceType> by prepending an string is mapped to the DNS-SD <ServiceType> by prepending an
underscore and appending a period followed by the "_udp" label. For underscore and appending a period followed by the "_udp" label. For
example, rt="dali" is mapped into "_dali._udp". example, rt="dali" is mapped into "_dali._udp".
skipping to change at page 33, line 5 skipping to change at page 35, line 33
and a service subtype name consisting of a Net-Unicode text string, and a service subtype name consisting of a Net-Unicode text string,
without underscore or period and limited to 63 octets. This string without underscore or period and limited to 63 octets. This string
is mapped to the DNS-SD <ServiceType> by appending a period followed is mapped to the DNS-SD <ServiceType> by appending a period followed
by the "_sub" label and then appending a period followed by the by the "_sub" label and then appending a period followed by the
service type label pair derived as in the previous paragraph. For service type label pair derived as in the previous paragraph. For
example, rt="dali.light" is mapped into "light._sub._dali._udp". example, rt="dali.light" is mapped into "light._sub._dali._udp".
The resulting string is used to form labels for DNS-SD records which The resulting string is used to form labels for DNS-SD records which
are stored directly in the DNS. are stored directly in the DNS.
9.4. Domain mapping 10.4. Domain mapping
DNS domains may be derived from the "d" attribute. The domain DNS domains may be derived from the "d" attribute. The domain
attribute may be suffixed with the zone name of the authoritative DNS attribute may be suffixed with the zone name of the authoritative DNS
server to generate the domain name. The "ep" attribute is prefixed server to generate the domain name. The "ep" attribute is prefixed
to the domain name to generate the FQDN to be stored into DNS with an to the domain name to generate the FQDN to be stored into DNS with an
AAAA RR. AAAA RR.
9.5. TXT Record key=value strings 10.5. TXT Record key=value strings
A number of [RFC6763] key/value pairs are derived from link-format A number of [RFC6763] key/value pairs are derived from link-format
information, to be exported in the DNS-SD as key=value strings in a information, to be exported in the DNS-SD as key=value strings in a
TXT record ([RFC6763], Section 6.3). TXT record ([RFC6763], Section 6.3).
The resource <URI> is exported as key/value pair "path=<URI>". The resource <URI> is exported as key/value pair "path=<URI>".
The Interface Description "if" attribute is exported as key/value The Interface Description "if" attribute is exported as key/value
pair "if=<Interface Description>". pair "if=<Interface Description>".
The DNS TXT record can be further populated by importing any other The DNS TXT record can be further populated by importing any other
resource description attributes as they share the same key=value resource description attributes as they share the same key=value
format specified in Section 6 of [RFC6763]. format specified in Section 6 of [RFC6763].
9.6. Importing resource links into DNS-SD 10.6. Importing resource links into DNS-SD
Assuming the ability to query a Resource Directory or multicast a GET Assuming the ability to query a Resource Directory or multicast a GET
(?exp) over the local link, CoAP resource discovery may be used to (?exp) over the local link, CoAP resource discovery may be used to
populate the DNS-SD database in an automated fashion. CoAP resource populate the DNS-SD database in an automated fashion. CoAP resource
descriptions (links) can be exported to DNS-SD for exposure to descriptions (links) can be exported to DNS-SD for exposure to
service discovery by using the Resource Instance attribute as the service discovery by using the Resource Instance attribute as the
basis for a unique service name, composed with the Resource Type as basis for a unique service name, composed with the Resource Type as
the <ServiceType>, and registered in the correct <Domain>. The agent the <ServiceType>, and registered in the correct <Domain>. The agent
responsible for exporting records to the DNS zone file SHOULD be responsible for exporting records to the DNS zone file SHOULD be
authenticated to the DNS server. The following example shows an authenticated to the DNS server. The following example shows an
agent discovering a resource to be exported: agent discovering a resource to be exported:
Agent RD
| |
| --- GET /rd-lookup/res?exp ------------------------------> |
| |
| |
| <-- 2.05 Content "<coap://[FDFD::1234]:5683/light/1>;exp; |
| rt="dali.light";ins="Spot"; |
| d="office";ep="node1" |
| |
Req: GET /rd-lookup/res?exp Req: GET /rd-lookup/res?exp
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::1234]:5683/light/1>; <coap://[FDFD::1234]:5683/light/1>;
exp;rt="dali.light";ins="Spot"; exp;rt="dali.light";ins="Spot";
d="office";ep="node1" d="office";ep="node1"
The agent subsequently registers the following DNS-SD RRs, assuming a The agent subsequently registers the following DNS-SD RRs, assuming a
zone name "example.com" prefixed with "office": zone name "example.com" prefixed with "office":
skipping to change at page 34, line 30 skipping to change at page 36, line 47
Spot._dali._udp.office.example.com IN SRV 0 0 5683 Spot._dali._udp.office.example.com IN SRV 0 0 5683
node1.office.example.com. node1.office.example.com.
Spot._dali._udp.office.example.com IN TXT Spot._dali._udp.office.example.com IN TXT
txtver=1;path=/light/1 txtver=1;path=/light/1
In the above figure the Service Name is chosen as In the above figure the Service Name is chosen as
Spot._dali._udp.office.example.com without the light._sub service Spot._dali._udp.office.example.com without the light._sub service
prefix. An alternative Service Name would be: prefix. An alternative Service Name would be:
Spot.light._sub._dali._udp.office.example.com. Spot.light._sub._dali._udp.office.example.com.
10. Security Considerations 11. Security Considerations
The security considerations as described in Section 7 of [RFC5988] The security considerations as described in Section 7 of [RFC5988]
and Section 6 of [RFC6690] apply. The "/.well-known/core" resource and Section 6 of [RFC6690] apply. The "/.well-known/core" resource
may be protected e.g. using DTLS when hosted on a CoAP server as may be protected e.g. using DTLS when hosted on a CoAP server as
described in [RFC7252]. DTLS or TLS based security SHOULD be used on described in [RFC7252]. DTLS or TLS based security SHOULD be used on
all resource directory interfaces defined in this document. all resource directory interfaces defined in this document.
10.1. Endpoint Identification and Authentication 11.1. Endpoint Identification and Authentication
An Endpoint is determined to be unique by an RD by the Endpoint An Endpoint is determined to be unique by an RD by the Endpoint
identifier parameter included during Registration, and any associated identifier parameter included during Registration, and any associated
TLS or DTLS security bindings. An Endpoint MUST NOT be identified by TLS or DTLS security bindings. An Endpoint MUST NOT be identified by
its protocol, port or IP address as these may change over the its protocol, port or IP address as these may change over the
lifetime of an Endpoint. lifetime of an Endpoint.
Every operation performed by an Endpoint or Client on a resource Every operation performed by an Endpoint or Client on a resource
directory SHOULD be mutually authenticated using Pre-Shared Key, Raw directory SHOULD be mutually authenticated using Pre-Shared Key, Raw
Public Key or Certificate based security. Endpoints using a Public Key or Certificate based security. Endpoints using a
Certificate MUST include the Endpoint identifier as the Subject of Certificate MUST include the Endpoint identifier as the Subject of
the Certificate, and this identifier MUST be checked by a resource the Certificate, and this identifier MUST be checked by a resource
directory to match the Endpoint identifier included in the directory to match the Endpoint identifier included in the
Registration message. Registration message.
10.2. Access Control 11.2. Access Control
Access control SHOULD be performed separately for the RD Function Set Access control SHOULD be performed separately for the RD Function Set
and the RD Lookup Function Set, as different endpoints may be and the RD Lookup Function Set, as different endpoints may be
authorized to register with an RD from those authorized to lookup authorized to register with an RD from those authorized to lookup
endpoints from the RD. Such access control SHOULD be performed in as endpoints from the RD. Such access control SHOULD be performed in as
fine-grained a level as possible. For example access control for fine-grained a level as possible. For example access control for
lookups could be performed either at the domain, endpoint or resource lookups could be performed either at the domain, endpoint or resource
level. level.
10.3. Denial of Service Attacks 11.3. Denial of Service Attacks
Services that run over UDP unprotected are vulnerable to unknowingly Services that run over UDP unprotected are vulnerable to unknowingly
become part of a DDoS attack as UDP does not require return become part of a DDoS attack as UDP does not require return
routability check. Therefore, an attacker can easily spoof the routability check. Therefore, an attacker can easily spoof the
source IP of the target entity and send requests to such a service source IP of the target entity and send requests to such a service
which would then respond to the target entity. This can be used for which would then respond to the target entity. This can be used for
large-scale DDoS attacks on the target. Especially, if the service large-scale DDoS attacks on the target. Especially, if the service
returns a response that is order of magnitudes larger than the returns a response that is order of magnitudes larger than the
request, the situation becomes even worse as now the attack can be request, the situation becomes even worse as now the attack can be
amplified. DNS servers have been widely used for DDoS amplification amplified. DNS servers have been widely used for DDoS amplification
attacks. Recently, it has been observed that NTP Servers, that also attacks. There is also a danger that NTP Servers could become
run on unprotected UDP have been used for DDoS attacks implicated in denial-of-service (DoS) attacks since they run on
(http://tools.cisco.com/security/center/content/CiscoSecurityNotice/ unprotected UDP, there is no return routability check, and they can
CVE-2013-5211) since there is no return routability check and can
have a large amplification factor. The responses from the NTP server have a large amplification factor. The responses from the NTP server
were found to be 19 times larger than the request. A Resource were found to be 19 times larger than the request. A Resource
Directory (RD) which responds to wild-card lookups is potentially Directory (RD) which responds to wild-card lookups is potentially
vulnerable if run with CoAP over UDP. Since there is no return vulnerable if run with CoAP over UDP. Since there is no return
routability check and the responses can be significantly larger than routability check and the responses can be significantly larger than
requests, RDs can unknowingly become part of a DDoS amplification requests, RDs can unknowingly become part of a DDoS amplification
attack. Therefore, it is RECOMMENDED that implementations ensure attack. Therefore, it is RECOMMENDED that implementations ensure
return routability. This can be done, for example by responding to return routability. This can be done, for example by responding to
wild card lookups only over DTLS or TLS or TCP. wild card lookups only over DTLS or TLS or TCP.
11. IANA Considerations 12. IANA Considerations
11.1. Resource Types 12.1. Resource Types
"core.rd", "core.rd-group" and "core.rd-lookup" resource types need "core.rd", "core.rd-group" and "core.rd-lookup" resource types need
to be registered with the resource type registry defined by to be registered with the resource type registry defined by
[RFC6690]. [RFC6690].
11.2. Link Extension 12.2. Link Extension
The "exp" attribute needs to be registered when a future Web Linking The "exp" and "ins" attributes need to be registered when a future
link-extension registry is created (e.g. in RFC5988bis). Web Linking link-extension registry is created (e.g. in RFC5988bis).
11.3. RD Parameter Registry 12.3. IPv6 ND Resource Directory Address Option
This document registers one new ND option type under the subregistry
"IPv6 Neighbor Discovery Option Formats":
o Resource Directory address Option (38)
12.4. RD Parameter Registry
This specification defines a new sub-registry for registration and This specification defines a new sub-registry for registration and
lookup parameters called "RD Parameters" under "CoRE Parameters". lookup parameters called "RD Parameters" under "CoRE Parameters".
Although this specification defines a basic set of parameters, it is Although this specification defines a basic set of parameters, it is
expected that other standards that make use of this interface will expected that other standards that make use of this interface will
define new ones. define new ones.
Each entry in the registry must include the human readable name of Each entry in the registry must include the human readable name of
the parameter, the query parameter, validity requirements if any and the parameter, the query parameter, validity requirements if any and
a description. The query parameter MUST be a valid URI query key a description. The query parameter MUST be a valid URI query key
[RFC3986]. [RFC3986].
Initial entries in this sub-registry are as follows: Initial entries in this sub-registry are as follows:
+----------+-------+---------------+--------------------------------+ +-----------+-------+---------------+-------------------------------+
| Name | Query | Validity | Description | | Name | Query | Validity | Description |
+----------+-------+---------------+--------------------------------+ +-----------+-------+---------------+-------------------------------+
| Endpoint | ep | | Name of the endpoint | | Endpoint | ep | | Name of the endpoint, max 63 |
| Name | | | | | Name | | | bytes |
| Lifetime | lt | 60-4294967295 | Lifetime of the registration | | Lifetime | lt | 60-4294967295 | Lifetime of the registration |
| | | | in seconds | | | | | in seconds |
| Domain | d | | Domain to which this endpoint | | Domain | d | | Domain to which this endpoint |
| | | | belongs | | | | | belongs |
| Endpoint | et | | Semantic name of the endpoint | | Endpoint | et | | Semantic name of the endpoint |
| Type | | | | | Type | | | |
| Context | con | URI | The scheme, address and port | | Context | con | URI | The scheme, address and port |
| | | | at which this server is | | | | | at which this server is |
| | | | available | | | | | available |
| Endpoint | ep | | Name of the endpoint, max 63 | | Resource | res | | Name of the resource |
| Name | | | bytes | | Name | | | |
| Group | gp | | Name of a group in the RD | | Group | gp | | Name of a group in the RD |
| Name | | | | | Name | | | |
| Page | page | Integer | Used for pagination | | Page | page | Integer | Used for pagination |
| Count | count | Integer | Used for pagination | | Count | count | Integer | Used for pagination |
+----------+-------+---------------+--------------------------------+ | Resource | ins | | Instance Identifier |
| Instance | | | |
| Export | exp | | A link MAY be exported to |
| | | | another Resource Directory |
+-----------+-------+---------------+-------------------------------+
Table 1: RD Parameters Table 1: RD Parameters
The IANA policy for future additions to the sub-registry is "Expert The IANA policy for future additions to the sub-registry is "Expert
Review" as described in [RFC5226]. Review" as described in [RFC5226].
12. Examples 13. Examples
Examples are added here. Examples are added here.
12.1. Lighting Installation 13.1. Lighting Installation
This example shows a simplified lighting installation which makes use This example shows a simplified lighting installation which makes use
of the Resource Directory (RD) with a CoAP interface to facilitate of the Resource Directory (RD) with a CoAP interface to facilitate
the installation and start up of the application code in the lights the installation and start up of the application code in the lights
and sensors. In particular, the example leads to the definition of a and sensors. In particular, the example leads to the definition of a
group and the enabling of the corresponding multicast address. No group and the enabling of the corresponding multicast address. No
conclusions must be drawn on the realization of actual installation conclusions must be drawn on the realization of actual installation
procedures, because the example "emphasizes" some of the issues that or naming procedures, because the example only "emphasizes" some of
may influence the use of the RD. the issues that may influence the use of the RD and does not pretend
to be normative.
12.1.1. Installation Characteristics 13.1.1. Installation Characteristics
The example assumes that the installation is managed. That means The example assumes that the installation is managed. That means
that a Commissioning Tool (CT) is used to authorize the addition of that a Commissioning Tool (CT) is used to authorize the addition of
nodes, name them, and name their services. The CT can be connected nodes, name them, and name their services. The CT can be connected
to the installation in many ways: the CT can be part of the to the installation in many ways: the CT can be part of the
installation network, connected by WiFi to the installation network, installation network, connected by WiFi to the installation network,
or connected via GPRS link, or other method. or connected via GPRS link, or other method.
It is assumed that there are two naming authorities for the It is assumed that there are two naming authorities for the
installation: (1) the network manager that is responsible for the installation: (1) the network manager that is responsible for the
correct operation of the network and the connected interfaces, and correct operation of the network and the connected interfaces, and
(2) the lighting manager that is responsible for the correct (2) the lighting manager that is responsible for the correct
functioning of networked lights and sensors. The result is the functioning of networked lights and sensors. The result is the
existence of two naming schemes coming from the two managing existence of two naming schemes coming from the two managing
entities. entities.
The example installation consists of one presence sensor, and two The example installation consists of one presence sensor, and two
luminaries, luminary1 and luminary2, each with their own wireless luminaries, luminary1 and luminary2, each with their own wireless
interface. Each luminary contains three lamps: left, right and interface. Each luminary contains three lamps: left, right and
middle. Each luminary is accessible through one end-point. For each middle. Each luminary is accessible through one endpoint. For each
lamp a resource exists to modify the settings of a lamp in a lamp a resource exists to modify the settings of a lamp in a
luminary. The purpose of the installation is that the presence luminary. The purpose of the installation is that the presence
sensor notifies the presence of persons to a group of lamps. The sensor notifies the presence of persons to a group of lamps. The
group of lamps consists of: middle and left lamps of luminary1 and group of lamps consists of: middle and left lamps of luminary1 and
right lamp of luminary2. right lamp of luminary2.
Before commissioning by the lighting manager, the network is Before commissioning by the lighting manager, the network is
installed and access to the interfaces is proven to work by the installed and access to the interfaces is proven to work by the
network manager. Following the lay-out of cables and routers the network manager.
network manager has defined DNS domains. The presence sensor and
luminary1 are part of DNS domain: rtr_5612_rrt.example.com and
luminary2 is part of rtr_7899_pfa.example.com. The names of
luminary1- luminary2-, and sensor- interfaces are respectively:
lm_12-345-678, lm_12-456-378, and sn_12-345-781. These names are
stored in DNS together with their IP addresses. The FQDN of the
interfaces is shown in Table 2 below:
+--------------------+----------------------------------------+
| Name | FQDN |
+--------------------+----------------------------------------+
| luminary1 | lm_12-345-678.rtr_5612_rrt.example.com |
| luminary2 | lm_12-456-378.rtr_7899_pfa.example.com |
| Presence sensor | sn_12-345-781.rtr_5612_rrt.example.com |
| Resource directory | pc_123456.rtr_5612_rrt.example.com |
+--------------------+----------------------------------------+
Table 2: interface FQDNs
At the moment of installation, the network under installation is not At the moment of installation, the network under installation is not
necessarily connected to the DNS infra structure. Therefore, SLAAC necessarily connected to the DNS infra structure. Therefore, SLAAC
IPv6 addresses are assigned to CT, RD, luminaries and sensor shown in IPv6 addresses are assigned to CT, RD, luminaries and sensor shown in
Table 3 below: Table 2 below:
+--------------------+--------------+ +--------------------+--------------+
| Name | IPv6 address | | Name | IPv6 address |
+--------------------+--------------+ +--------------------+--------------+
| luminary1 | FDFD::ABCD:1 | | luminary1 | FDFD::ABCD:1 |
| luminary2 | FDFD::ABCD:2 | | luminary2 | FDFD::ABCD:2 |
| Presence sensor | FDFD::ABCD:3 | | Presence sensor | FDFD::ABCD:3 |
| Resource directory | FDFD::ABCD:0 | | Resource directory | FDFD::ABCD:0 |
+--------------------+--------------+ +--------------------+--------------+
Table 3: interface SLAAC addresses Table 2: interface SLAAC addresses
In Section 12.1.2 the use of resource directory during installation In Section 13.1.2 the use of resource directory during installation
is presented. In Section 12.1.3 the connection to DNS is discussed. is presented. In Section 13.1.3 the connection to DNS is discussed.
12.1.2. RD entries 13.1.2. RD entries
It is assumed that access to the DNS infrastructure is not always It is assumed that access to the DNS infrastructure is not always
possible during installation. Therefore, the SLAAC addresses are possible during installation. Therefore, the SLAAC addresses are
used in this section. used in this section.
For discovery, the resource types (rt) of the devices are important. For discovery, the resource types (rt) of the devices are important.
The lamps in the luminaries have rt: light, and the presence sensor The lamps in the luminaries have rt: light, and the presence sensor
has rt: p-sensor. The end-points have names which are relevant to has rt: p-sensor. The endpoints have names which are relevant to the
the light installation manager. In this case luminary1, luminary2, light installation manager. In this case luminary1, luminary2, and
and the presence sensor are located in room 2-4-015, where luminary1 the presence sensor are located in room 2-4-015, where luminary1 is
is located at the window and luminary2 and the presence sensor are located at the window and luminary2 and the presence sensor are
located at the door. The end-point names reflect this physical located at the door. The endpoint names reflect this physical
location. The middle, left and right lamps are accessed via path location. The middle, left and right lamps are accessed via path
/light/middle, /light/left, and /light/right respectively. The /light/middle, /light/left, and /light/right respectively. The
identifiers relevant to the Resource Directory are shown in Table 4 identifiers relevant to the Resource Directory are shown in Table 3
below: below:
+----------------+------------------+---------------+---------------+ +----------------+------------------+---------------+---------------+
| Name | end-point | resource path | resource type | | Name | endpoint | resource path | resource type |
+----------------+------------------+---------------+---------------+ +----------------+------------------+---------------+---------------+
| luminary1 | lm_R2-4-015_wndw | /light/left | light | | luminary1 | lm_R2-4-015_wndw | /light/left | light |
| luminary1 | lm_R2-4-015_wndw | /light/middle | light | | luminary1 | lm_R2-4-015_wndw | /light/middle | light |
| luminary1 | lm_R2-4-015_wndw | /light/right | light | | luminary1 | lm_R2-4-015_wndw | /light/right | light |
| luminary2 | lm_R2-4-015_door | /light/left | light | | luminary2 | lm_R2-4-015_door | /light/left | light |
| luminary2 | lm_R2-4-015_door | /light/middle | light | | luminary2 | lm_R2-4-015_door | /light/middle | light |
| luminary2 | lm_R2-4-015_door | /light/right | light | | luminary2 | lm_R2-4-015_door | /light/right | light |
| Presence | ps_R2-4-015_door | /ps | p-sensor | | Presence | ps_R2-4-015_door | /ps | p-sensor |
| sensor | | | | | sensor | | | |
+----------------+------------------+---------------+---------------+ +----------------+------------------+---------------+---------------+
Table 4: Resource Directory identifiers Table 3: Resource Directory identifiers
The CT inserts the end-points of the luminaries and the sensor in the The CT inserts the endpoints of the luminaries and the sensor in the
RD using the Context parameter (con) to specify the interface RD using the Context parameter (con) to specify the interface
address: address:
Req: POST coap://[FDFD::ABCD:0]/rd Req: POST coap://[FDFD::ABCD:0]/rd
?ep=lm_R2-4-015_wndw&con=coap://[FDFD::ABCD:1] ?ep=lm_R2-4-015_wndw&con=coap://[FDFD::ABCD:1]
Payload: Payload:
</light/left>;rt="light"; </light/left>;rt="light"; d="R2-4-015",
d="R2-4-015";ins="lamp4444";exp, </light/middle>;rt="light"; d="R2-4-015",
</light/middle>;rt="light"; </light/right>;rt="light";d="R2-4-015"
d="R2-4-015";ins="lamp5555";exp,
</light/right>;rt="light";
d="R2-4-015";ins="lamp6666";exp
Res: 2.01 Created Res: 2.01 Created
Location: /rd/4521 Location: /rd/4521
Req: POST coap://[FDFD::ABCD:0]/rd Req: POST coap://[FDFD::ABCD:0]/rd
?ep=lm_R2-4-015_door&con=coap://[FDFD::ABCD:2] ?ep=lm_R2-4-015_door&con=coap://[FDFD::ABCD:2]
Payload: Payload:
</light/left>;rt="light"; </light/left>;rt="light"; d="R2-4-015",
d="R2-4-015";ins="lamp1111";exp, </light/middle>;rt="light"; d="R2-4-015",
</light/middle>;rt="light"; </light/right>;rt="light"; d="R2-4-015"
d="R2-4-015";ins="lamp2222";exp,
</light/right>;rt="light";
d="R2-4-015";ins="lamp3333";exp
Res: 2.01 Created Res: 2.01 Created
Location: /rd/4522 Location: /rd/4522
Req: POST coap://[FDFD::ABCD:0]/rd Req: POST coap://[FDFD::ABCD:0]/rd
?ep=ps_R2-4-015_door&con=coap://[FDFD::ABCD:3] ?ep=ps_R2-4-015_door&con=coap://[FDFD::ABCD:3]
Payload: Payload:
</ps>;rt="p-sensor"; </ps>;rt="p-sensor"; d="R2-4-015"
d="R2-4-015";ins="pres1234";exp
Res: 2.01 Created Res: 2.01 Created
Location: /rd/4523 Location: /rd/4523
The domain name d="R2-4-015" has been added for an efficient lookup The domain name d="R2-4-015" has been added for an efficient lookup
because filtering on "ep" name is awkward. The same domain name is because filtering on "ep" name is more awkward. The same domain name
communicated to the two luminaries and the presence sensor by the CT. is communicated to the two luminaries and the presence sensor by the
The "exp" attribute is set for the later administration in DNS of the CT.
instance name ins="lampxxxx".
Once the individual endpoints are registered, the group needs to be
registered. Because the presence sensor sends one multicast message
to the luminaries, all lamps in the group need to have an identical
path. This path is created on the two luminaries using the batch
command defined in [I-D.ietf-core-interfaces]. The path to a batch
of lamps is defined as: /light/grp1. In the example below, two
endpoints are updated with an additional resource using the path
/light/grp1 on the two luminaries.
Req: POST
coap://[FDFD::ABCD:1]/light/grp1
(Content-Format:application/link-format)<light/middle>,<light/left>
Res: 2.04 Changed
Req: POST
coap://[FDFD::ABCD:2]/light/grp1
(Content-Format:application/link-format)<light/right>
Res: 2.04 Changed
The group is specified in the RD. The Context parameter is set to The group is specified in the RD. The Context parameter is set to
the site-local multicast address allocated to the group. In the POST the site-local multicast address allocated to the group. In the POST
in the example below, these two end-points and the end-point of the in the example below, these two endpoints and the endpoint of the
presence sensor are registered as members of the group. presence sensor are registered as members of the group.
It is expected that Standards Developing Organizations (SDOs) may
develop other special purpose protocols to specify additional group
links, group membership, group names and other parameters in the
individual nodes.
Req: POST coap://[FDFD::ABCD:0]/rd-group Req: POST coap://[FDFD::ABCD:0]/rd-group
?gp=grp_R2-4-015;con="coap//[FF05::1]";exp;ins="grp1234" ?gp=grp_R2-4-015;con="coap//[FF05::1]";exp;ins="grp1234"
Payload: Payload:
<>ep=lm_R2-4-015_wndw, <>ep=lm_R2-4-015_wndw,
<>ep=lm_R2-4-015_door, <>ep=lm_R2-4-015_door,
<>ep=ps_R2-4-015_door <>ep=ps_R2-4-015_door
Res: 2.01 Created Res: 2.01 Created
Location: /rd-group/501 Location: /rd-group/501
After the filling of the RD by the CT, the application in the After the filling of the RD by the CT, the application in the
luminaries can learn to which groups they belong, and enable their luminaries can learn to which groups they belong, and enable their
interface for the multicast address. interface for the multicast address.
The luminary, knowing its domain, queries the RD for the end-point The luminary, knowing its domain, queries the RD for the endpoint
with rt=light and d=R2-4-015. The RD returns all end-points in the with rt=light and d=R2-4-015. The RD returns all endpoints in the
domain. domain.
Req: GET coap://[FDFD::ABCD:0]/rd-lookup/ep Req: GET coap://[FDFD::ABCD:0]/rd-lookup/ep
?d=R2-4-015;rt=light ?d=R2-4-015;rt=light
Res: 2.05 Content Res: 2.05 Content
<coap://[FDFD::ABCD:1]>; <coap://[FDFD::ABCD:1]>;
ep="lm_R2-4-015_wndw", ep="lm_R2-4-015_wndw",
<coap://[FDFD::ABCD:2]>; <coap://[FDFD::ABCD:2]>;
ep="lm_R2-4-015_door" ep="lm_R2-4-015_door"
Knowing its own IPv6 address, the luminary discovers its endpoint Knowing its own IPv6 address, the luminary discovers its endpoint
name. With the end-point name the luminary queries the RD for all name. With the endpoint name the luminary queries the RD for all
groups to which the end-point belongs. groups to which the endpoint belongs.
Req: GET coap://[FDFD::ABCD:0]/rd-lookup/gp Req: GET coap://[FDFD::ABCD:0]/rd-lookup/gp
?ep=lm_R2-4-015_wndw ?ep=lm_R2-4-015_wndw
Res: 2.05 Content Res: 2.05 Content
<coap://[FF05::1]>;gp="grp_R2-4-015" <coap://[FF05::1]>;gp="grp_R2-4-015"
From the context parameter value, the luminary learns the multicast From the context parameter value, the luminary learns the multicast
address of the multicast group. address of the multicast group.
Alternatively, the CT can communicate the multicast address directly Alternatively, the CT can communicate the multicast address directly
to the luminaries by using the "coap-group" resource specified in to the luminaries by using the "coap-group" resource specified in
[RFC7390]. [RFC7390].
Req: POST //[FDFD::ABCD:1]/coap-group Req: POST //[FDFD::ABCD:1]/coap-group
Content-Format: application/coap-group+json Content-Format: application/coap-group+json
{ "a": "[FF05::1]" } { "a": "[FF05::1]",
{ "n": "grp_R2-4-015"} "n": "grp_R2-4-015"}
Res: 2.01 Created Res: 2.01 Created
Location-Path: /coap-group/1 Location-Path: /coap-group/1
Dependent on the situation only the address ,"a", or the name, "n", Dependent on the situation only the address ,"a", or the name, "n",
is specified in the coap-group resource. Instead of the RD group is specified in the coap-group resource.
name also the DNS group name can be used.
12.1.3. DNS entries
The network manager assigns the domain bc.example.com to the entries
coming from the RD. The agent that looks up the resource directory
uses the domain name bc.example.com as prescribed, to enter the
services and hosts into the DNS.
The agent does a lookup as specified in Section 9.6. The RD returns
all entries annotated with "exp". The agent subsequently registers
the following DNS-SD RRs:
lm_R2-4-015_wndw.bc.example.com. IN AAAA FDFD::ABCD:1
lm_R2-4-015_door.bc.example.com. IN AAAA FDFD::ABCD:2
ps_R2-4-015_door.bc.example.com. IN AAAA FDFD::ABCD:3
_light._udp.bc.example.com IN PTR
lamp1111._light._udp.bc.example.com
_light._udp.bc.example.com IN PTR
lamp2222._light._udp.bc.example.com
_light._udp.bc.example.com IN PTR
lamp3333._light._udp.bc.example.com
_light._udp.bc.example.com IN PTR
lamp4444._light._udp.bc.example.com
_light._udp.bc.example.com IN PTR
lamp5555._light._udp.bc.example.com
_light._udp.bc.example.com IN PTR
lamp6666._light._udp.bc.example.com
_p-sensor._udp.bc.example.com IN PTR
pres12324._p-sensor._udp.bc.example.com
lamp1111._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_door.bc.example.com.
lamp1111._light._udp.bc.example.com IN TXT
txtver=1;path=/light/left
lamp2222._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_door.bc.example.com.
lamp2222._light._udp.bc.example.com IN TXT
txtver=1;path=/light/middle
lamp3333._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_door.bc.example.com.
lamp3333._light._udp.bc.example.com IN TXT
txtver=1;path=/light/right
lamp4444._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_wndw.bc.example.com.
lamp4444._light._udp.bc.example.com IN TXT
txtver=1;path=/light/left
lamp5555._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_wndw.bc.example.com.
lamp5555._light._udp.bc.example.com IN TXT
txtver=1;path=/light/middle
lamp6666._light._udp.bc.example.com IN SRV 0 0 5683
lm_R2-4-015_wndw.bc.example.com.
lamp6666._light._udp.bc.example.com IN TXT
txtver=1;path=/light/right
pres1234._p-sensor._udp.bc.example.com IN SRV 0 0 5683
ps_R2-4-015_door.bc.example.com.
pres1234._p-sensor._udp.bc.example.com IN TXT
txtver=1;path=/ps
To ask for all lamps is equivalent to returning all PTR RR with label
_light.udp.bc.example.com. from the DNS. When it is required to
filter on the rd=R2-4-015 value in the DNS, additional PTR RRs have
to be entered into the DNS.
R2-4-015._light._udp.bc.example.com IN PTR
lamp1111._light._udp.bc.example.com
R2-4-015._light._udp.bc.example.com IN PTR
lamp2222._light._udp.bc.example.com
R2-4-015._light._udp.bc.example.com IN PTR
lamp3333._light._udp.bc.example.com
R2-4-015._light._udp.bc.example.com IN PTR
lamp4444._light._udp.bc.example.com
R2-4-015._light._udp.bc.example.com IN PTR
lamp5555._light._udp.bc.example.com
R2-4-015._light._udp.bc.example.com IN PTR
lamp6666._light._udp.bc.example.com
Returning all PTR RRs with label R2-4-015._light._udp.bc.example.com 13.1.3. DNS entries
provides all service instances within the domain R2-4-015. This
filtering can be handy when there are many rooms. In the example
there is only one room, making the filtering superfluous.
The agent can also discover groups that need to be discovered. It It may be profitable to discover the light groups for applications,
queries RD to return all groups which are exported. which are unaware ot the existence of the RD. An agent needs to
query the RD to return all groups which are exported to be inserted
into DNS.
Req: GET /rd-lookup/gp?exp Req: GET /rd-lookup/gp?exp
Res: 2.05 Content Res: 2.05 Content
<coap://[FF05::1]/>;exp;gp="grp_R2-4-015;ins="grp1234"; <coap://[FF05::1]/>;exp;gp="grp_R2-4-015;ins="grp1234";
ep="lm_R2-4-015_wndw"; ep="lm_R2-4-015_wndw";
ep="lm_R2-4-015_door ep="lm_R2-4-015_door
The group with FQDN grp_R2-4-015.bc.example.com can be entered into The group with FQDN grp_R2-4-015.bc.example.com can be entered into
the DNS by the agent. The accompanying instance name is grp1234. the DNS by the agent. The accompanying instance name is grp1234.
skipping to change at page 45, line 5 skipping to change at page 44, line 32
following RRs into the DNS. following RRs into the DNS.
grp_R2-4-015.bc.example.com. IN AAAA FF05::1 grp_R2-4-015.bc.example.com. IN AAAA FF05::1
_group._udp.bc.example.com IN PTR _group._udp.bc.example.com IN PTR
grp1234._group._udp.bc.example.com grp1234._group._udp.bc.example.com
grp1234._group._udp.bc.example.com IN SRV 0 0 5683 grp1234._group._udp.bc.example.com IN SRV 0 0 5683
grp_R2-4-015_door.bc.example.com. grp_R2-4-015_door.bc.example.com.
grp1234._group._udp.bc.example.com IN TXT grp1234._group._udp.bc.example.com IN TXT
txtver=1;path=/light/grp1 txtver=1;path=/light/grp1
12.1.4. RD Operation From then on applications, not familiar with the existence of the RD,
can use DNS to access the lighting group.
The specification of the group can be used by devices other than the
luminaries and the sensor to learn the multicast address of the group
in a given room. For example a smart phone may be used to adjust the
lamps in the room.
After entry into the room, on request of the user, the smart phone
queries the presence of RDs and may display all the domain names
found on the RDs. The user can, for example, scroll all domains
(room names in this case) and select the room that he entered. After
selection the phone shows all groups in the selected room with their
members. Selecting a group, the user can dim, switch on/off the
group of lights, or possibly even create temporary new groups.
In all examples the SLAAC IPv6 address can be exchanged with the
FQDN, when a connection to DNS exists. Using the FQDN, a node learns
the interface's IPv6 address, or the group's multicast address from
DNS. In the same way the presence sensor can learn the multicast
address to which it should send its presence messages.
12.2. OMA Lightweight M2M (LWM2M) Example 13.2. OMA Lightweight M2M (LWM2M) Example
This example shows how the OMA LWM2M specification makes use of This example shows how the OMA LWM2M specification makes use of
Resource Directory (RD). Resource Directory (RD).
OMA LWM2M is a profile for device services based on CoAP, CoRE RD, OMA LWM2M is a profile for device services based on CoAP(OMA Name
and other IETF RFCs and drafts. LWM2M defines a simple object model Authority). LWM2M defines a simple object model and a number of
and a number of abstract interfaces and operations for device abstract interfaces and operations for device management and device
management and device service enablement. service enablement.
An LWM2M server is an instance of an LWM2M middleware service layer, An LWM2M server is an instance of an LWM2M middleware service layer,
containing a Resource Directory along with other LWM2M interfaces containing a Resource Directory along with other LWM2M interfaces
defined by the LWM2M specification. defined by the LWM2M specification.
CoRE Resource Directory (RD) is used to provide the LWM2M CoRE Resource Directory (RD) is used to provide the LWM2M
Registration interface. Registration interface.
LWM2M does not provide for registration domains and does not LWM2M does not provide for registration domains and does not
currently use the rd-group or rd-lookup interfaces. currently use the rd-group or rd-lookup interfaces.
skipping to change at page 46, line 7 skipping to change at page 45, line 18
The LWM2M specification describes a set of interfaces and a resource The LWM2M specification describes a set of interfaces and a resource
model used between a LWM2M device and an LWM2M server. Other model used between a LWM2M device and an LWM2M server. Other
interfaces, proxies, applications, and function sets are currently interfaces, proxies, applications, and function sets are currently
out of scope for LWM2M. out of scope for LWM2M.
The location of the LWM2M Server and RD Function Set is provided by The location of the LWM2M Server and RD Function Set is provided by
the LWM2M Bootstrap process, so no dynamic discovery of the RD the LWM2M Bootstrap process, so no dynamic discovery of the RD
function set is used. LWM2M Servers and endpoints are not required function set is used. LWM2M Servers and endpoints are not required
to implement the ./well-known/core resource. to implement the ./well-known/core resource.
12.2.1. The LWM2M Object Model 13.2.1. The LWM2M Object Model
The OMA LWM2M object model is based on a simple 2 level class The OMA LWM2M object model is based on a simple 2 level class
hierarchy consisting of Objects and Resources. hierarchy consisting of Objects and Resources.
An LWM2M Resource is a REST endpoint, allowed to be a single value or An LWM2M Resource is a REST endpoint, allowed to be a single value or
an array of values of the same data type. an array of values of the same data type.
An LWM2M Object is a resource template and container type that An LWM2M Object is a resource template and container type that
encapsulates a set of related resources. An LWM2M Object represents encapsulates a set of related resources. An LWM2M Object represents
a specific type of information source; for example, there is a LWM2M a specific type of information source; for example, there is a LWM2M
skipping to change at page 46, line 40 skipping to change at page 46, line 4
{/base-uri}{/object-id}{/object-instance}{/resource-id}{/resource- {/base-uri}{/object-id}{/object-instance}{/resource-id}{/resource-
instance} instance}
The five variables given here are strings. base-uri can also have The five variables given here are strings. base-uri can also have
the special value "undefined" (sometimes called "null" in RFC 6570). the special value "undefined" (sometimes called "null" in RFC 6570).
Each of the variables object-instance, resource-id, and resource- Each of the variables object-instance, resource-id, and resource-
instance can be the special value "undefined" only if the values instance can be the special value "undefined" only if the values
behind it in this sequence also are "undefined". As a special case, behind it in this sequence also are "undefined". As a special case,
object-instance can be "empty" (which is different from "undefined") object-instance can be "empty" (which is different from "undefined")
if resource-id is not "undefined". [_TEMPLATE_TODO] if resource-id is not "undefined". [_TEMPLATE_TODO]
base-uri := Base URI for LWM2M resources or "undefined" for default base-uri := Base URI for LWM2M resources or "undefined" for default
(empty) base URI (empty) base URI
object-id := OMNA registered object ID (0-65535) object-id := OMNA (OMA Name Authority) registered object ID (0-65535)
object-instance := Object instance identifier (0-65535) or object-instance := Object instance identifier (0-65535) or
"undefined"/"empty" (see above)) to refer to all instances of an "undefined"/"empty" (see above)) to refer to all instances of an
object ID object ID
resource-id := OMNA registered resource ID (0-65535) or "undefined" resource-id := OMNA (OMA Name Authority) registered resource ID
to refer to all resources within an instance (0-65535) or "undefined" to refer to all resources within an instance
resource-instance := Resource instance identifier or "undefined" to resource-instance := Resource instance identifier or "undefined" to
refer to single instance of a resource refer to single instance of a resource
LWM2M IDs are 16 bit unsigned integers represented in decimal (no LWM2M IDs are 16 bit unsigned integers represented in decimal (no
leading zeroes except for the value 0) by URI format strings. For leading zeroes except for the value 0) by URI format strings. For
example, a LWM2M URI might be: example, a LWM2M URI might be:
/1/0/1 /1/0/1
The base uri is empty, the Object ID is 1, the instance ID is 0, the The base uri is empty, the Object ID is 1, the instance ID is 0, the
resource ID is 1, and the resource instance is "undefined". This resource ID is 1, and the resource instance is "undefined". This
example URI points to internal resource 1, which represents the example URI points to internal resource 1, which represents the
registration lifetime configured, in instance 0 of a type 1 object registration lifetime configured, in instance 0 of a type 1 object
(LWM2M Server Object). (LWM2M Server Object).
12.2.2. LWM2M Register Endpoint 13.2.2. LWM2M Register Endpoint
LWM2M defines a registration interface based on the Resource LWM2M defines a registration interface based on the Resource
Directory Function Set, described in Section 5. The URI of the LWM2M Directory Function Set, described in Section 6. The URI of the LWM2M
Resource Directory function set is specified to be "/rd" as Resource Directory function set is specified to be "/rd" as
recommended in Section 5.2. recommended in Section 6.3.
LWM2M endpoints register object IDs, for example </1>, to indicate LWM2M endpoints register object IDs, for example </1>, to indicate
that a particular object type is supported, and register object that a particular object type is supported, and register object
instances, for example </1/0>, to indicate that a particular instance instances, for example </1/0>, to indicate that a particular instance
of that object type exists. of that object type exists.
Resources within the LWM2M object instance are not registered with Resources within the LWM2M object instance are not registered with
the RD, but may be discovered by reading the resource links from the the RD, but may be discovered by reading the resource links from the
object instance using GET with a CoAP Content-Format of application/ object instance using GET with a CoAP Content-Format of application/
link-format. Resources may also be read as a structured object by link-format. Resources may also be read as a structured object by
performing a GET to the object instance with a Content-Format of performing a GET to the object instance with a Content-Format of
senml+json. senml+json.
When an LWM2M object or instance is registered, this indicates to the When an LWM2M object or instance is registered, this indicates to the
LWM2M server that the object and it's resources are available for LWM2M server that the object and its resources are available for
management and service enablement (REST API) operations. management and service enablement (REST API) operations.
LWM2M endpoints may use the following RD registration parameters as LWM2M endpoints may use the following RD registration parameters as
defined in Table 1 : defined in Table 1 :
ep - Endpoint Name ep - Endpoint Name
lt - registration lifetime lt - registration lifetime
Endpoint Name is mandatory, all other registration parameters are Endpoint Name is mandatory, all other registration parameters are
optional. optional.
skipping to change at page 48, line 17 skipping to change at page 47, line 32
+------------+-------+-------------------------------+--------------+ +------------+-------+-------------------------------+--------------+
| Protocol | b | {"U",UQ","S","SQ","US","UQS"} | Available | | Protocol | b | {"U",UQ","S","SQ","US","UQS"} | Available |
| Binding | | | Protocols | | Binding | | | Protocols |
| | | | | | | | | |
| LWM2M | ver | 1.0 | Spec Version | | LWM2M | ver | 1.0 | Spec Version |
| Version | | | | | Version | | | |
| | | | | | | | | |
| SMS Number | sms | | MSISDN | | SMS Number | sms | | MSISDN |
+------------+-------+-------------------------------+--------------+ +------------+-------+-------------------------------+--------------+
Table 5: LWM2M Additional Registration Parameters Table 4: LWM2M Additional Registration Parameters
The following RD registration parameters are not currently specified The following RD registration parameters are not currently specified
for use in LWM2M: for use in LWM2M:
et - Endpoint Type et - Endpoint Type
con - Context con - Context
The endpoint registration must include a payload containing links to The endpoint registration must include a payload containing links to
all supported objects and existing object instances, optionally all supported objects and existing object instances, optionally
including the appropriate link-format relations. including the appropriate link-format relations.
skipping to change at page 48, line 39 skipping to change at page 48, line 5
Here is an example LWM2M registration payload: Here is an example LWM2M registration payload:
</1>,</1/0>,</3/0>,</5> </1>,</1/0>,</3/0>,</5>
This link format payload indicates that object ID 1 (LWM2M Server This link format payload indicates that object ID 1 (LWM2M Server
Object) is supported, with a single instance 0 existing, object ID 3 Object) is supported, with a single instance 0 existing, object ID 3
(LWM2M Device object) is supported, with a single instance 0 (LWM2M Device object) is supported, with a single instance 0
existing, and object 5 (LWM2M Firmware Object) is supported, with no existing, and object 5 (LWM2M Firmware Object) is supported, with no
existing instances. existing instances.
12.2.3. Alternate Base URI 13.2.3. Alternate Base URI
If the LWM2M endpoint exposes objects at a base URI other than the If the LWM2M endpoint exposes objects at a base URI other than the
default empty base path, the endpoint must register the base URI default empty base path, the endpoint must register the base URI
using rt="oma.lwm2m". An example link payload using alternate base using rt="oma.lwm2m". An example link payload using alternate base
URI would be: URI would be:
</my_lwm2m>;rt="oma.lwm2m",</my_lwm2m/1>,<my_lwm2m/1/0>,<my_lwm2m/5> </my_lwm2m>;rt="oma.lwm2m",</my_lwm2m/1>,<my_lwm2m/1/0>,<my_lwm2m/5>
This link payload indicates that the lwm2m objects will be placed This link payload indicates that the lwm2m objects will be placed
under the base URI "/my_lwm2m" and that object ID 1 (server) is under the base URI "/my_lwm2m" and that object ID 1 (server) is
supported, with a single instance 0 existing, and object 5 (firmware supported, with a single instance 0 existing, and object 5 (firmware
update) is supported. update) is supported.
12.2.4. LWM2M Update Endpoint Registration 13.2.4. LWM2M Update Endpoint Registration
An LWM2M Registration update proceeds as described in Section 5.3, An LWM2M Registration update proceeds as described in Section 6.4,
and adds some optional parameter updates: and adds some optional parameter updates:
lt - Registration Lifetime lt - Registration Lifetime
b - Protocol Binding b - Protocol Binding
sms - MSISDN sms - MSISDN
link payload - new or modified links link payload - new or modified links
A Registration update is also specified to be used to update the A Registration update is also specified to be used to update the
LWM2M server whenever the endpoint's UDP port or IP address are LWM2M server whenever the endpoint's UDP port or IP address are
changed. changed.
12.2.5. LWM2M De-Register Endpoint 13.2.5. LWM2M De-Register Endpoint
LWM2M allows for de-registration using the delete method on the LWM2M allows for de-registration using the delete method on the
returned location from the initial registration operation. LWM2M de- returned location from the initial registration operation. LWM2M de-
registration proceeds as described in Section 5.4. registration proceeds as described in Section 6.5.
13. Acknowledgments 14. Acknowledgments
Srdjan Krco, Szymon Sasin, Kerry Lynn, Esko Dijk, Anders Brandt, Oscar Novo, Srdjan Krco, Szymon Sasin, Kerry Lynn, Esko Dijk, Anders
Matthieu Vial, Mohit Sethi, Sampo Ukkola and Linyi Tian have provided Brandt, Matthieu Vial, Mohit Sethi, Sampo Ukkola and Linyi Tian have
helpful comments, discussions and ideas to improve and shape this provided helpful comments, discussions and ideas to improve and shape
document. Section 9 is based on an earlier draft by Kerry Lynn. this document. Section 9 is based on an earlier draft by Kerry Lynn.
Zach would also like to thank his colleagues from the EU FP7 SENSEI Zach would also like to thank his colleagues from the EU FP7 SENSEI
project, where many of the resource directory concepts were project, where many of the resource directory concepts were
originally developed. originally developed.
14. Changelog 15. Changelog
changes from -07 to -08
o removed link target value returned from domain and group lookup
types
o Maximum length of domain parameter 63 bytes for consistency with
group
o removed option for simple POST of link data, don't require a
.well-known/core resource to accept POST data and handle it in a
special way; we already have /rd for that
o add IPv6 ND Option for discovery of an RD
o clarify group configuration section 6.1 that endpoints must be
registered before including them in a group
o removed all superfluous client-server diagrams
o simplified lighting example
o introduced Commissioning Tool
o RD-Look-up text is extended.
changes from -06 to -07 changes from -06 to -07
o added text in the discovery section to allow content format hints o added text in the discovery section to allow content format hints
to be exposed in the discovery link attributes to be exposed in the discovery link attributes
o editorial updates to section 9 o editorial updates to section 9
o update author information o update author information
skipping to change at page 52, line 29 skipping to change at page 52, line 22
o Added the concept of an RD Domain and a registration parameter for o Added the concept of an RD Domain and a registration parameter for
it. it.
o Recommended the Location returned from a registration to be o Recommended the Location returned from a registration to be
stable, allowing for endpoint and Domain information to be changed stable, allowing for endpoint and Domain information to be changed
during updates. during updates.
o Changed the lookup interface to accept endpoint and Domain as o Changed the lookup interface to accept endpoint and Domain as
query string parameters to control the scope of a lookup. query string parameters to control the scope of a lookup.
15. References 16. References
15.1. Normative References 16.1. Normative References
[I-D.ietf-core-links-json] [I-D.ietf-core-links-json]
Li, K., Rahman, A., and C. Bormann, "Representing CoRE Li, K., Rahman, A., and D. Bormann, "Representing CoRE
Formats in JSON and CBOR", draft-ietf-core-links-json-04 Formats in JSON and CBOR", draft-ietf-core-links-json-05
(work in progress), November 2015. (work in progress), April 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <http://www.rfc-editor.org/info/rfc3986>.
skipping to change at page 53, line 33 skipping to change at page 53, line 29
<http://www.rfc-editor.org/info/rfc6690>. <http://www.rfc-editor.org/info/rfc6690>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<http://www.rfc-editor.org/info/rfc6763>. <http://www.rfc-editor.org/info/rfc6763>.
[RFC7396] Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396, [RFC7396] Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396,
DOI 10.17487/RFC7396, October 2014, DOI 10.17487/RFC7396, October 2014,
<http://www.rfc-editor.org/info/rfc7396>. <http://www.rfc-editor.org/info/rfc7396>.
15.2. Informative References 16.2. Informative References
[I-D.ietf-core-interfaces]
Shelby, Z., Vial, M., and M. Koster, "Reusable Interface
Definitions for Constrained RESTful Environments", draft-
ietf-core-interfaces-04 (work in progress), October 2015.
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities", [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>. <http://www.rfc-editor.org/info/rfc1034>.
[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
Application and Support", STD 3, RFC 1123, Application and Support", STD 3, RFC 1123,
DOI 10.17487/RFC1123, October 1989, DOI 10.17487/RFC1123, October 1989,
<http://www.rfc-editor.org/info/rfc1123>. <http://www.rfc-editor.org/info/rfc1123>.
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