draft-ietf-core-interfaces-10.txt		draft-ietf-core-interfaces-11.txt
	CoRE Working Group Z. Shelby		CoRE Working Group Z. Shelby
	Internet-Draft ARM		Internet-Draft ARM
	Intended status: Informational M. Vial		Intended status: Informational M. Vial
	Expires: March 18, 2018 Schneider-Electric		Expires: September 6, 2018 Schneider-Electric
	M. Koster		M. Koster
	SmartThings		SmartThings
	C. Groves		C. Groves
	J. Zhu		J. Zhu
	Huawei		Huawei
	B. Silverajan, Ed.		B. Silverajan, Ed.
	Tampere University of Technology		Tampere University of Technology
	September 14, 2017		March 05, 2018
	Reusable Interface Definitions for Constrained RESTful Environments		Reusable Interface Definitions for Constrained RESTful Environments
	draft-ietf-core-interfaces-10		draft-ietf-core-interfaces-11
	Abstract		Abstract
	This document defines a set of Constrained RESTful Environments		This document defines a set of Constrained RESTful Environments
	(CoRE) Link Format Interface Descriptions [RFC6690] applicable for		(CoRE) Link Format Interface Descriptions [RFC6690] applicable for
	use in constrained environments. These include the: Actuator,		use in constrained environments. These include the: Actuator,
	Parameter, Read-only parameter, Sensor, Batch, Linked Batch and Link		Parameter, Read-only parameter, Sensor, Batch, Linked Batch and Link
	List interfaces.		List interfaces.
	The Batch, Linked Batch and Link List interfaces make use of resource		The Batch, Linked Batch and Link List interfaces make use of resource
	collections. This document further describes how collections relate		collections. This document further describes how collections relate
	to interfaces.		to interfaces.
	Many applications require a set of interface descriptions in order		Many applications require a set of interface descriptions in order
	provide the required functionality. This document defines the		provide the required functionality. This document defines an
	concept of function sets to specify this set of interfaces and		Interface Description atribute value to describe resources conforming
	resources.		to a particular interface.
	Editor's notes:		Editor's notes:
	o The git repository for the draft is found at https://github.com/		o The git repository for the draft is found at https://github.com/
	core-wg/interfaces		core-wg/interfaces
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 https://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 March 18, 2018.		This Internet-Draft will expire on September 6, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2018 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		(https://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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	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. Collections . . . . . . . . . . . . . . . . . . . . . . . . . 5		3. Collections . . . . . . . . . . . . . . . . . . . . . . . . . 5
	3.1. Introduction to Collections . . . . . . . . . . . . . . . 5		3.1. Introduction to Collections . . . . . . . . . . . . . . . 5
	3.2. Use Cases for Collections . . . . . . . . . . . . . . . . 6		3.2. Use Cases for Collections . . . . . . . . . . . . . . . . 5
	3.3. Content-Formats for Collections . . . . . . . . . . . . . 6		3.3. Content-Formats for Collections . . . . . . . . . . . . . 6
	3.4. Links and Items in Collections . . . . . . . . . . . . . 7		3.4. Link Embedding . . . . . . . . . . . . . . . . . . . . . 6
	3.5. Queries on Collections . . . . . . . . . . . . . . . . . 8		3.5. Links and Items in Collections . . . . . . . . . . . . . 7
	3.6. Observing Collections . . . . . . . . . . . . . . . . . . 8		3.6. Queries on Collections . . . . . . . . . . . . . . . . . 8
	3.7. Collection Types . . . . . . . . . . . . . . . . . . . . 8		3.7. Observing Collections . . . . . . . . . . . . . . . . . . 8
			3.8. Collection Types . . . . . . . . . . . . . . . . . . . . 8
	4. Interface Descriptions . . . . . . . . . . . . . . . . . . . 9		4. Interface Descriptions . . . . . . . . . . . . . . . . . . . 9
	4.1. Link List . . . . . . . . . . . . . . . . . . . . . . . . 11		4.1. Link List . . . . . . . . . . . . . . . . . . . . . . . . 11
	4.2. Batch . . . . . . . . . . . . . . . . . . . . . . . . . . 11		4.2. Batch . . . . . . . . . . . . . . . . . . . . . . . . . . 11
	4.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 12		4.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 12
	4.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 13		4.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 13
	4.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 14		4.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 14
	4.6. Read-only Parameter . . . . . . . . . . . . . . . . . . . 14		4.6. Read-only Parameter . . . . . . . . . . . . . . . . . . . 14
	4.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 14		4.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 14
	5. Security Considerations . . . . . . . . . . . . . . . . . . . 15		5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
	skipping to change at page 3, line 15 ¶		skipping to change at page 3, line 16 ¶
	6.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 16		6.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 16
	6.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 16		6.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 16
	6.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 16		6.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 16
	6.6. Read-only parameter . . . . . . . . . . . . . . . . . . . 17		6.6. Read-only parameter . . . . . . . . . . . . . . . . . . . 17
	6.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 17		6.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 17
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
	8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 18		8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 18
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 21		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
	9.1. Normative References . . . . . . . . . . . . . . . . . . 21		9.1. Normative References . . . . . . . . . . . . . . . . . . 21
	9.2. Informative References . . . . . . . . . . . . . . . . . 21		9.2. Informative References . . . . . . . . . . . . . . . . . 21
	Appendix A. Current Usage of Interfaces and Function Sets . . . 22		Appendix A. Current Usage of Interfaces and Function Sets . . . 23
	A.1. Constrained RESTful Environments (CoRE) Link Format		A.1. Constrained RESTful Environments (CoRE) Link Format
	(IETF) . . . . . . . . . . . . . . . . . . . . . . . . . 23		(IETF) . . . . . . . . . . . . . . . . . . . . . . . . . 23
	A.2. CoRE Resource Directory (IETF) . . . . . . . . . . . . . 23		A.2. CoRE Resource Directory (IETF) . . . . . . . . . . . . . 23
	A.3. Open Connectivity Foundation (OCF) . . . . . . . . . . . 23		A.3. Open Connectivity Foundation (OCF) . . . . . . . . . . . 23
	A.4. oneM2M . . . . . . . . . . . . . . . . . . . . . . . . . 24		A.4. oneM2M . . . . . . . . . . . . . . . . . . . . . . . . . 24
	A.5. OMA LWM2M . . . . . . . . . . . . . . . . . . . . . . . . 24		A.5. OMA LWM2M . . . . . . . . . . . . . . . . . . . . . . . . 25
	Appendix B. Resource Profile example . . . . . . . . . . . . . . 25		Appendix B. Resource Profile example . . . . . . . . . . . . . . 25
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
	1. Introduction		1. Introduction
	IETF Standards for machine to machine communication in constrained		IETF Standards for machine to machine communication in constrained
	environments describe a REST protocol and a set of related		environments describe a REST protocol and a set of related
	information standards that may be used to represent machine data and		information standards that may be used to represent machine data and
	machine metadata in REST interfaces. CoRE Link-format is a standard		machine metadata in REST interfaces. CoRE Link-format is a standard
	for doing Web Linking [RFC5988] in constrained environments. SenML		for doing Web Linking [RFC8288] in constrained environments. SenML
	[I-D.ietf-core-senml] is a simple data model and representation		[I-D.ietf-core-senml] is a simple data model and representation
	format for composite and complex structured resources. CoRE Link-		format for composite and complex structured resources. CoRE Link-
	Format and SenML can be used by CoAP [RFC7252] or HTTP servers.		Format and SenML can be used by CoAP [RFC7252] or HTTP servers.
	The discovery of resources offered by a constrained server is very		The discovery of resources offered by a constrained server is very
	important in machine-to-machine applications where there are no		important in machine-to-machine applications where there are no
	humans in the loop. Machine application clients must be able to		humans in the loop. Machine application clients must be able to
	adapt to different resource organizations without advance knowledge		adapt to different resource organizations without advance knowledge
	of the specific data structures hosted by each connected thing. The		of the specific data structures hosted by each connected thing. The
	use of Web Linking for the description and discovery of resources		use of Web Linking for the description and discovery of resources
	hosted by constrained web servers is specified by CoRE Link Format		hosted by constrained origin servers is specified by CoRE Link Format
	[RFC6690]. CoRE Link Format additionally defines a link attribute		[RFC6690]. CoRE Link Format additionally defines a link attribute
	for interface description ("if") that can be used to describe the		for interface description ("if") that can be used to describe the
	REST interface of a resource, and may include a link to a description		REST interface of a resource, and may include a link to a description
	document.		document.
	This document defines a set of Link Format interface descriptions for		This document defines a set of Link Format interface descriptions for
	some common design patterns that enable the server side composition		some common design patterns that enable the server side composition
	and organization, and client side discovery and consumption, of		and organization, and client side discovery and consumption, of
	machine resources using Web Linking. A client discovering the "if"		machine resources using Web Linking. A client discovering the "if"
	link attribute will be able to consume resources based on its		link attribute will be able to consume resources based on its
	skipping to change at page 4, line 34 ¶		skipping to change at page 4, line 35 ¶
	interfaces described can also be realized using HTTP [RFC7230].		interfaces described can also be realized using HTTP [RFC7230].
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in		"OPTIONAL" in this document are to be interpreted as described in
	[RFC2119].		[RFC2119].
	This document requires readers to be familiar with all the terms and		This document requires readers to be familiar with all the terms and
	concepts that are discussed in [RFC5988] and [RFC6690]. This		concepts that are discussed in [RFC8288] and [RFC6690]. This
	document makes use of the following additional terminology:		document makes use of the following additional terminology:
	Gradual Reveal: A REST design where resources are discovered		Gradual Reveal: A REST design where resources are discovered
	progressively using Web Linking.		progressively using Web Linking.
	Interface Description: The Interface Description describes the		Interface Description: The Interface Description describes the
	generic REST interface to interact with a resource or a set of		generic REST interface to interact with a resource or a set of
	resources. Its use is described via the Interface Description		resources. Its use is described via the Interface Description
	'if' attribute which is an opaque string used to provide a name or		'if' attribute which is an opaque string used to provide a name or
	URI indicating a specific interface definition used to interact		URI indicating a specific interface definition used to interact
	with the target resource. One can think of this as describing		with the target resource. One can think of this as describing
	verbs usable on a resource.		verbs usable on a resource.
	Resource Discovery: The process allowing a web client to identify		Resource Discovery: The process allowing a client to identify
	resources being hosted on a web server.		resources being hosted on an origin server.
	Service Discovery: The process making it possible for a web client
	to automatically detect devices and Function Sets offered by these
	devices on a CoRE network.
	3. Collections		3. Collections
	3.1. Introduction to Collections		3.1. Introduction to Collections
	A Collection is a resource which represents one or more related		A Collection is a resource which represents one or more related
	resources. [RFC6573] describes the "item" and "collection" Link		resources. [RFC6573] describes the "item" and "collection" Link
	Relation. "item" link relation identifies a member of collection.		Relation. An "item" link relation identifies a member of collection.
	"collection" indicates the collection that an item is a member of.		A "collection" indicates the collection that an item is a member of.
	For example: A collection might be a resource representing catalog of		For example, a collection might be a resource representing a catalog
	products, an item is a resource related to an individual product.		of products, while an item is a resource related to an individual
			product.
	Section 1.2.2/[RFC6690] also describes resource collections.		Section 1.2.2/[RFC6690] also describes resource collections.
	This document uses the concept of "collection" and applies it to		This document uses the concept of "collection" and applies it to
	interface descriptions. A collection interface description consists		interface descriptions. A collection interface description consists
	of a set of links and a set of items pointed to by the links which		of a set of links and a set of items pointed to by the links which
	may be sub-resources of the collection resource. The collection		may be sub-resources of the collection resource. The collection
	interface descriptions described in this document are Link List,		interface descriptions described in this document are Link List,
	Batch and Linked Batch.		Batch and Linked Batch.
	skipping to change at page 5, line 44 ¶		skipping to change at page 5, line 41 ¶
	A particular resource item may be a member of more than one		A particular resource item may be a member of more than one
	collection at a time by being linked to, but may only be a		collection at a time by being linked to, but may only be a
	subresource of one collection.		subresource of one collection.
	Some collections may have pre-configured items and links, and some		Some collections may have pre-configured items and links, and some
	collections may support dynamic creation and removal of items and		collections may support dynamic creation and removal of items and
	links. Likewise, modification of items in some collections may be		links. Likewise, modification of items in some collections may be
	permitted, and not in others.		permitted, and not in others.
	Collections may support link embedding, which is analogous to an
	image tag (link) causing the image to display inline in a browser
	window. Resources pointed to by embedded links in collections may be
	interacted with using bulk operations on the collection resource.
	For example, performing a GET on a collection resource may return a
	single representation containing all of the linked resources.
	Links in collections may be selected for processing by a particular		Links in collections may be selected for processing by a particular
	request by using Query Filtering as described in CoRE Link-Format		request by using Query Filtering as described in CoRE Link-Format
	[RFC6690].		[RFC6690].
	3.2. Use Cases for Collections		3.2. Use Cases for Collections
	Collections may be used to provide gradual reveal of resources on an		Collections may be used to provide gradual reveal of resources on an
	endpoint. There may be a small set of links at the .well-known/core		endpoint. There may be a small set of links at the .well-known/core
	location, which may in turn point to other collections of resources		location, which may in turn point to other collections of resources
	that represent device information, device configuration, device		that represent device information, device configuration, device
	management, and various functional clusters of resources on the		management, and various functional clusters of resources on the
	device.		device.
	A collection may provide resource encapsulation, where link embedding
	may be used to provide a single resource with which a client may
	interact to obtain a set of related resource values. For example, a
	collection for manufacturer parameters may consist of manufacturer
	name, date of manufacture, location of manufacture, and serial number
	resources which can be read as a single senml data object.
	A collection may be used to group a set of like resources for bulk		A collection may be used to group a set of like resources for bulk
	state update or actuation. For example, the brightness control		state update or actuation. For example, the brightness control
	resources of a number of luminaries may be grouped by linking to them		resources of a number of luminaries may be grouped by linking to them
	in a collection. The collection type may support receiving a single		in a collection. The collection type may support receiving a single
	update form a client and sending that update to each resource item in		update from a client and sending that update to each resource item in
	the collection.		the collection.
	Items may be sub-resources of the collection resource. This enables		Items may be sub-resources of the collection resource. This enables
	updates to multiple items in the collection to be processed together		updates to multiple items in the collection to be processed together
	within the context of the collection resource.		within the context of the collection resource.
	3.3. Content-Formats for Collections		3.3. Content-Formats for Collections
	The collection interfaces by default use CoRE Link-Format for the		The collection interfaces by default use CoRE Link-Format for the
	link representations and SenML or text/plain for representations of		link representations and SenML or text/plain for representations of
	skipping to change at page 7, line 12 ¶		skipping to change at page 6, line 39 ¶
	by the Content-Format option in the header of the update request		by the Content-Format option in the header of the update request
	operation.		operation.
	The default Content-Formats for collection types described in this		The default Content-Formats for collection types described in this
	document are:		document are:
	Links: application/link-format, application/link-format+json		Links: application/link-format, application/link-format+json
	Items: application/senml+json, text/plain		Items: application/senml+json, text/plain
	3.4. Links and Items in Collections		3.4. Link Embedding
			Collections may provide resource encapsulation by supporting link
			embedding. Link embedding may be used to provide a single resource
			with which a client may interact to obtain a set of related resource
			values. This is analogous to an image tag (link) causing the image
			to display inline in a browser window. Link embedding enables the
			bulk processing of items in the collection using a single operation
			targeting the collection resource. Performing a GET on a collection
			resource may return a single representation containing all of the
			embedded linked resources. For example, a collection for
			manufacturer parameters may consist of manufacturer name, date of
			manufacture, location of manufacture, and serial number resources
			which can be read as a single senml data object.
			A subset of resources in the collection may be selected for operation
			using Query Filtering. Bulk Read operations using GET return a SenML
			representation of all selected resources. Bulk item Update
			operations using PUT or POST apply the payload document to all
			selected resource items in the collection, using either a Batch or
			Group update policy. A Batch update is performed by applying the
			resource values in the payload document to all resources in the
			collection that match any resource name in the payload document.
			Group updates are performed by applying the payload document to each
			item in the collection. Group updates are indicated by the link
			relation type rel="grp" in the link.
			3.5. Links and Items in Collections
	Links use CoRE Link-Format representation by default and may point to		Links use CoRE Link-Format representation by default and may point to
	any resource reachable from the context of the collection. This		any resource reachable from the context of the collection. This
	includes absolute links and links that point to other network		includes links to resources with absolute paths as well as links that
	locations if the context of the collection allows. Links to sub-		point to other network locations, if the context of the collection
	resources in the collection MUST have a path-element starting with		allows. Links to sub-resources in the collection MUST have a path-
	the resource name, as per [RFC3986]. Links to resources in the		element starting with the resource name, as per [RFC3986]. Links to
	global context MUST start with a root path identifier [RFC5988].		resources in the global context MUST start with a root path
	Links to other collections are formed per [RFC3986].		identifier [RFC8288]. Links to other collections are formed per
			[RFC3986].
	Examples of links:		Examples of links:
	</sen/>;if="core.lb"': Link to the /sen/ collection describing it as		</sen/>;if="core.lb": Link to the /sen/ collection describing it as
	a core.lb type collection (Linked Batch)		a core.lb type collection (Linked Batch)
	</sen/>;rel="grp"': Link to the /sen/ collection indicating that		</sen/>;rel="grp": Link to the /sen/ collection indicating that
	/sen/ is a member of a group in the collection in which the link		/sen/ is a member of a group in the collection in which the link
	appears.		appears.
	<"/sen/temp">;rt="temperature"': An absolute link to the resource at		</sen/temp>;rt="temperature": A link to the temp resource with an
	the path /sen/temp		absolute path.
	<temp>;rt="temperature": Link to the temp subresource of the		<temp>;rt="temperature": Link to the temp subresource of the
	collection in which this link appears."		collection in which this link appears.
	<temp>;anchor="/sen/": A link to the temp subresource of the		<temp>;anchor="/sen/": A link to the temp subresource of the
	collection /sen/ which is assumed not to be a subresource of the		collection /sen/ which is assumed not to be a subresource of the
	collection in which the link appears ,but is expected to be		collection in which the link appears, but is expected to be
	identified in the collection by resource name.		identified in the collection by resource name.
	Links in the collection MAY be Read, Updated, Added, or Removed using		Links in the collection MAY be Read, Updated, Added, or Removed using
	the CoRE Link-Format or JSON Merge-Patch Content-Formats on the		the CoRE Link-Format or JSON Merge-Patch Content-Formats on the
	collection resource. Reading links uses the GET method and returns		collection resource. Reading links uses the GET method and returns
	an array or list containing the link-values of all selected links.		an array or list containing the link-values of all selected links.
	Links may be added to the collection using POST or PATCH methods.		Links may be added to the collection using POST or PATCH methods.
	Updates to links MUST use the PATCH method and MAY use query		Updates to links MUST use the PATCH method and MAY use query
	filtering to select links for updating. The PATCH method on links		filtering to select links for updating. The PATCH method on links
	MUST use the JSON Merge-Patch Content-Format (application/merge-		MUST use the JSON Merge-Patch Content-Format (application/merge-
	patch+json) specified in [RFC7396].		patch+json) specified in [RFC7396].
	Items in the collection SHOULD be represented using the SenML		Items in the collection SHOULD be represented using the SenML
	(application/senml+json) or plain text (text/plain) Content-Formats,		(application/senml+json) or plain text (text/plain) Content-Formats,
	depending on whether the representation is of a single data point or		depending on whether the representation is of a single data point or
	multiple data points. Items MAY be represented using any supported		multiple data points. Items MAY be represented using any supported
	skipping to change at page 8, line 11 ¶		skipping to change at page 8, line 17 ¶
	filtering to select links for updating. The PATCH method on links		filtering to select links for updating. The PATCH method on links
	MUST use the JSON Merge-Patch Content-Format (application/merge-		MUST use the JSON Merge-Patch Content-Format (application/merge-
	patch+json) specified in [RFC7396].		patch+json) specified in [RFC7396].
	Items in the collection SHOULD be represented using the SenML		Items in the collection SHOULD be represented using the SenML
	(application/senml+json) or plain text (text/plain) Content-Formats,		(application/senml+json) or plain text (text/plain) Content-Formats,
	depending on whether the representation is of a single data point or		depending on whether the representation is of a single data point or
	multiple data points. Items MAY be represented using any supported		multiple data points. Items MAY be represented using any supported
	Content-Format.		Content-Format.
	Link Embedding enables the bulk processing of items in the collection		3.6. Queries on Collections
	using a single operation targeting the collection resource. A subset
	of resources in the collection may be selected for operation using
	Query Filtering. Bulk Read operations using GET return a SenML
	representation of all selected resources. Bulk item Update
	operations using PUT or POST apply the payload document to all
	selected resource items in the collection, using either a Batch or
	Group update policy. A Batch update is performed by applying the
	resource values in the payload document to all resources in the
	collection that match any resource name in the payload document.
	Group updates are performed by applying the payload document to each
	item in the collection. Group updates are indicated by the link
	relation type rel="grp" in the link.
	3.5. Queries on Collections
	Collections MAY support query filtering as defined in CoRE Link-		Collections MAY support query filtering as defined in CoRE Link-
	Format [RFC6690]. Operations targeting either the links or the items		Format [RFC6690]. Operations targeting either the links or the items
	MAY select a subset of links and items in the collection by using		MAY select a subset of links and items in the collection by using
	query filtering. The Content-Format specified in the request header		query filtering. The Content-Format specified in the request header
	selects whether links or items are targeted by the operation.		selects whether links or items are targeted by the operation.
	3.6. Observing Collections		3.7. Observing Collections
	Resource Observation via [I-D.ietf-core-dynlink] using CoAP [RFC7252]		Resource Observation via [I-D.ietf-core-dynlink] using CoAP [RFC7252]
	MAY be supported on items in a collection. A subset of the		MAY be supported on items in a collection. A subset of the
	conditional observe parameters MAY be specified to apply. In most		conditional observe parameters MAY be specified to apply. In most
	cases pmin and pmax are useful. Resource observation on a		cases pmin and pmax are useful. Resource observation on a
	collection's items resource returns the collection representation.		collection's resource returns the collection representation.
	Observation Responses, or notifications, SHOULD provide the		Observation Responses, or notifications, SHOULD provide the
	collection representations in SenML Content-Format. Notifications		collection representations in SenML Content-Format. Notifications
	MAY include multiple observations of the collection resource, with		MAY include multiple observations of the collection resource, with
	SenML time stamps indicating the observation times.		SenML time stamps indicating the observation times.
	3.7. Collection Types		3.8. Collection Types
	There are three collection types defined in this document:		There are three collection types defined in this document:
	+-----------------+---------+--------------------+		+-----------------+---------+--------------------+
	| Collection Type | if= | Content-Format |		| Collection Type | if= | Content-Format |
	+-----------------+---------+--------------------+		+-----------------+---------+--------------------+
	| Link List | core.ll | link-format |		| Link List | core.ll | link-format |
	| | | |		| | | |
	| Batch | core.b | link-format, senml |		| Batch | core.b | link-format, senml |
	| | | |		| | | |
	| Linked Batch | core.lb | link-format, senml |		| Linked Batch | core.lb | link-format, senml |
	+-----------------+---------+--------------------+		+-----------------+---------+--------------------+
	Table 1: Collection Type Summary		Table 1: Collection Type Summary
	The interface description defined in this document describes the		The interface description defined in this document offer a deeper
	methods and functions that may be applied to the collections.		explanation of the methods and functions that may be applied to the
			three collections.
	4. Interface Descriptions		4. Interface Descriptions
	This section defines REST interfaces for Link List, Batch, Sensor,		This section defines REST interfaces for Sensor, Parameter, Read-Only
	Parameter and Actuator resources. Variants such as Linked Batch or		Paramter and Actuator resource types, in addition to the Link List,
	Read-Only Parameter are also presented. Each type is described along		Batch and Linked Batch collection types. Each type is described
	with its Interface Description attribute value and valid methods.		along with its Interface Description attribute value, valid methods
	These are defined for each interface in the table below. These		and content formats. These are shown for each interface in the table
	interfaces can support plain text and/or SenML Media types.		below.
	The if= column defines the Interface Description (if=) attribute		The if= column defines the Interface Description (if=) attribute
	value to be used in the CoRE Link Format for a resource conforming to		value to be used in the CoRE Link Format for a resource conforming to
	that interface. When this value appears in the if= attribute of a		that interface. When this value appears in the if= attribute of a
	link, the resource MUST support the corresponding REST interface		link, the resource MUST support the corresponding REST interface
	described in this section. The resource MAY support additional		described in this section. The resource MAY support additional
	functionality, which is out of scope for this document. Although		functionality, which is out of scope for this document. Although
	these interface descriptions are intended to be used with the CoRE		these interface descriptions are intended to be used with the CoRE
	Link Format, they are applicable for use in any REST interface		Link Format, they are applicable for use in any REST interface
	definition.		definition.
	skipping to change at page 11, line 8 ¶		skipping to change at page 11, line 8 ¶
	</a/1/led>;rt="simple.act.led";if="core.a",		</a/1/led>;rt="simple.act.led";if="core.a",
	</a/2/led>;rt="simple.act.led";if="core.a",		</a/2/led>;rt="simple.act.led";if="core.a",
	</d/>;rt="simple.dev";if="core.ll",		</d/>;rt="simple.dev";if="core.ll",
	</l/>;if="core.lb",		</l/>;if="core.lb",
	Figure 1: Binding Interface Example		Figure 1: Binding Interface Example
	4.1. Link List		4.1. Link List
	The Link List interface is used to retrieve (GET) a list of resources		The Link List interface is used to retrieve (GET) a list of resources
	on a web server. The GET request SHOULD contain an Accept option		on an origin server. The GET request SHOULD contain an Accept option
	with the application/link-format content format. However if the		with the application/link-format content format. However if the
	resource does not support any other form of content-format the Accept		resource does not support any other form of content-format the Accept
	option MAY be elided.		option MAY be elided.
	Note: The use of an Accept option with application/link-format is		Note: The use of an Accept option with application/link-format is
	recommended even though it is not strictly needed for the link list		recommended even though it is not strictly needed for the link list
	interface because this interface is extended by the batch and linked		interface because this interface is extended by the batch and linked
	batch interfaces where different content-formats are possible.		batch interfaces where different content-formats are possible.
	The request returns a list of URI references with absolute paths to		The request returns a list of URI references with absolute paths to
	the resources as defined in CoRE Link Format. This interface is		the resources as defined in CoRE Link Format. This interface is
	typically used with a parent resource to enumerate sub-resources but		typically used with a parent resource to enumerate sub-resources but
	may be used to reference any resource on a web server.		may be used to reference any resource on an origin server.
	Link List is the base interface to provide gradual reveal of		Link List is the base interface to provide gradual reveal of
	resources on a CoRE web server, hence the root resource of a Function		resources on a CoRE origin server. Hence the root resource of a
	Set SHOULD implement this interface or an extension of this		Function Set SHOULD implement this interface or an extension of this
	interface.		interface.
	The following example interacts with a Link List /d containing		The following example interacts with a Link List /d containing
	Parameter sub-resources /d/name, /d/model.		Parameter sub-resources /d/name, /d/model.
	Req: GET /d/ (Accept:application/link-format)		Req: GET /d/ (Accept:application/link-format)
	Res: 2.05 Content (application/link-format)		Res: 2.05 Content (application/link-format)
	</d/name>;rt="simple.dev.n";if="core.p",		</d/name>;rt="simple.dev.n";if="core.p",
	</d/model>;rt="simple.dev.mdl";if="core.rp"		</d/model>;rt="simple.dev.mdl";if="core.rp"
	4.2. Batch		4.2. Batch
	The Batch interface is used to manipulate a collection of sub-		The Batch interface is used to manipulate a collection of sub-
	resources at the same time. The Batch interface description supports		resources at the same time. The Batch interface description supports
	the same methods as its sub-resources, and can be used to read (GET),		the same methods as its sub-resources, and can be used to read (GET),
	update (PUT) or apply (POST) the values of those sub-resource with a		update (PUT) or apply (POST) the values of those sub-resource with a
	single resource representation. The sub-resources of a Batch MAY be		single resource representation. The sub-resources of a Batch MAY be
	heterogeneous, a method used on the Batch only applies to sub-		heterogeneous. Hence, a method used on the Batch only applies to
	resources that support it. For example Sensor interfaces do not		sub-resources that support it. For example Sensor interfaces do not
	support PUT, and thus a PUT request to a Sensor member of that Batch		support PUT, and thus a PUT request to a Sensor member of that Batch
	would be ignored. A batch requires the use of SenML Media types in		would be ignored. A batch requires the use of SenML Media types in
	order to support multiple sub-resources.		order to support multiple sub-resources.
	In addition, the Batch interface is an extension of the Link List		In addition, the Batch interface is an extension of the Link List
	interface and in consequence MUST support the same methods. For		interface and in consequence MUST support the same methods. For
	example: a GET with an Accept:application/link-format on a resource		example, a GET with an Accept:application/link-format on a resource
	utilizing the batch interface will return the sub-resource links.		utilizing the batch interface will return the sub-resource links.
	The following example interacts with a Batch /s/ with Sensor sub-		The following example interacts with a Batch /s/ with Sensor sub-
	resources /s/light, /s/temp and /s/humidity.		resources /s/light, /s/temp and /s/humidity.
	Req: GET /s/		Req: GET /s/
	Res: 2.05 Content (application/senml+json)		Res: 2.05 Content (application/senml+json)
	{"e":[		{"e":[
	{ "n": "light", "v": 123, "u": "lx" },		{ "n": "light", "v": 123, "u": "lx" },
	{ "n": "temp", "v": 27.2, "u": "degC" },		{ "n": "temp", "v": 27.2, "u": "degC" },
	{ "n": "humidity", "v": 80, "u": "%RH" }],		{ "n": "humidity", "v": 80, "u": "%RH" }],
	}		}
	4.3. Linked Batch		4.3. Linked Batch
	The Linked Batch interface is an extension of the Batch interface.		The Linked Batch interface is an extension of the Batch interface.
	Contrary to the basic Batch which is a collection statically defined		Contrary to the basic Batch which is a collection statically defined
	by the web server, a Linked Batch is dynamically controlled by a web		by the origin server, a Linked Batch is dynamically controlled by a
	client. A Linked Batch resource has no sub-resources. Instead the		client. A Linked Batch resource has no sub-resources. Instead the
	resources forming the batch are referenced using Web Linking		resources forming the batch are referenced using Web Linking
	[RFC5988] and the CoRE Link Format [RFC6690]. A request with a POST		[RFC8288] and the CoRE Link Format [RFC6690]. A request with a POST
	method and a content format of application/link-format simply appends		method and a content format of application/link-format simply appends
	new resource links to the collection. The links in the payload MUST		new resource links to the collection. The links in the payload MUST
	reference a resource on the web server with an absolute path. A		reference a resource on the origin server with an absolute path. A
	DELETE request removes the entire collection. All other requests		DELETE request removes the entire collection. All other requests
	available for a basic Batch are still valid for a Linked Batch.		available for a basic Batch are still valid for a Linked Batch.
	The following example interacts with a Linked Batch /l/ and creates a		The following example interacts with a Linked Batch /l/ and creates a
	collection containing /s/light, /s/temp and /s/humidity in 2 steps.		collection containing /s/light, /s/temp and /s/humidity in 2 steps.
	Req: POST /l/ (Content-Format: application/link-format)		Req: POST /l/ (Content-Format: application/link-format)
	</s/light>,</s/temp>		</s/light>,</s/temp>
	Res: 2.04 Changed		Res: 2.04 Changed
	skipping to change at page 15, line 49 ¶		skipping to change at page 15, line 49 ¶
	6. IANA Considerations		6. IANA Considerations
	This document registers the following CoRE Interface Description		This document registers the following CoRE Interface Description
	(if=) Link Target Attribute Values.		(if=) Link Target Attribute Values.
	6.1. Link List		6.1. Link List
	Attribute Value: core.ll		Attribute Value: core.ll
	Description: The Link List interface is used to retrieve a list of		Description: The Link List interface is used to retrieve a list of
	resources on a web server.		resources on an origin server.
	Reference: This document. Note to RFC Editor - please insert the		Reference: This document. Note to RFC Editor - please insert the
	appropriate RFC reference.		appropriate RFC reference.
	Notes: None		Notes: None
	6.2. Batch		6.2. Batch
	Attribute Value: core.b		Attribute Value: core.b
	skipping to change at page 16, line 28 ¶		skipping to change at page 16, line 28 ¶
	appropriate RFC reference.		appropriate RFC reference.
	Notes: None		Notes: None
	6.3. Linked Batch		6.3. Linked Batch
	Attribute Value: core.lb		Attribute Value: core.lb
	Description: The Linked Batch interface is an extension of the Batch		Description: The Linked Batch interface is an extension of the Batch
	interface. Contrary to the basic Batch which is a collection		interface. Contrary to the basic Batch which is a collection
	statically defined by the web server, a Linked Batch is		statically defined by the origin server, a Linked Batch is
	dynamically controlled by a web client.		dynamically controlled by a client.
	Reference: This document. Note to RFC Editor - please insert the		Reference: This document. Note to RFC Editor - please insert the
	appropriate RFC reference.		appropriate RFC reference.
	Notes: None		Notes: None
	6.4. Sensor		6.4. Sensor
	Attribute Value: core.s		Attribute Value: core.s
	skipping to change at page 18, line 7 ¶		skipping to change at page 18, line 7 ¶
	Acknowledgement is given to colleagues from the SENSEI project who		Acknowledgement is given to colleagues from the SENSEI project who
	were critical in the initial development of the well-known REST		were critical in the initial development of the well-known REST
	interface concept, to members of the IPSO Alliance where further		interface concept, to members of the IPSO Alliance where further
	requirements for interface descriptions have been discussed, and to		requirements for interface descriptions have been discussed, and to
	Szymon Sasin, Cedric Chauvenet, Daniel Gavelle and Carsten Bormann		Szymon Sasin, Cedric Chauvenet, Daniel Gavelle and Carsten Bormann
	who have provided useful discussion and input to the concepts in this		who have provided useful discussion and input to the concepts in this
	document.		document.
	8. Changelog		8. Changelog
	Changes from -10 to 09:		Changes from -10 to 11:
	o Section 1: Amendments to remove discussing properties.		o New Section 3.4 on Link Embedding
	o		o Removed disused "Service discovery" terminology
			o Removed wording referring to discontinued function set concept
			Changes from -09 to -10:
			o Section 1: Amendments to remove discussing properties.
	o New author and editor added.		o New author and editor added.
	Changes from -08 to 09:		Changes from -08 to -09:
	o Section 3.6: Modified to indicate that the entire collection		o Section 3.6: Modified to indicate that the entire collection
	resource is returned.		resource is returned.
	o General: Added editor's note with open issues.		o General: Added editor's note with open issues.
	Changes from -07 to 08:		Changes from -07 to -08:
	o Section 3.3: Modified Accepts to Accept header option.		o Section 3.3: Modified Accepts to Accept header option.
	o Addressed the editor's note in Section 4.1 to clarify the use of		o Addressed the editor's note in Section 4.1 to clarify the use of
	the Accept option.		the Accept option.
	Changes from -06 to 07:		Changes from -06 to -07:
	o Corrected Figure 1 sub-resource names e.g. tmp to temp and hum to		o Corrected Figure 1 sub-resource names e.g. tmp to temp and hum to
	humidity.		humidity.
	o Addressed the editor's note in Section 4.2.		o Addressed the editor's note in Section 4.2.
	o Removed section on function sets and profiles as agreed to at the		o Removed section on function sets and profiles as agreed to at the
	IETF#97.		IETF#97.
	Changes from -05 to -06:		Changes from -05 to -06:
	skipping to change at page 21, line 14 ¶		skipping to change at page 21, line 19 ¶
	o Improved the WADL interface definition.		o Improved the WADL interface definition.
	o Added a simple profile example.		o Added a simple profile example.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[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, DOI 10.17487/		Requirement Levels", BCP 14, RFC 2119,
	RFC2119, March 1997, <https://www.rfc-editor.org/info/		DOI 10.17487/RFC2119, March 1997,
	rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC5988] Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/
	RFC5988, October 2010, <https://www.rfc-editor.org/info/
	rfc5988>.
	[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link		[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
	Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,		Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
	<https://www.rfc-editor.org/info/rfc6690>.		<https://www.rfc-editor.org/info/rfc6690>.
			[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
			DOI 10.17487/RFC8288, October 2017,
			<https://www.rfc-editor.org/info/rfc8288>.
	9.2. Informative References		9.2. Informative References
	[I-D.ietf-core-dynlink]		[I-D.ietf-core-dynlink]
	Shelby, Z., Vial, M., Koster, M., and C. Groves, "Dynamic		Shelby, Z., Koster, M., Groves, C., Zhu, J., and B.
	Resource Linking for Constrained RESTful Environments",		Silverajan, "Dynamic Resource Linking for Constrained
	draft-ietf-core-dynlink-03 (work in progress), March 2017.		RESTful Environments", draft-ietf-core-dynlink-04 (work in
			progress), September 2017.
	[I-D.ietf-core-resource-directory]		[I-D.ietf-core-resource-directory]
	Shelby, Z., Koster, M., Bormann, C., Stok, P., and C.		Shelby, Z., Koster, M., Bormann, C., Stok, P., and C.
	Amsuess, "CoRE Resource Directory", draft-ietf-core-		Amsuess, "CoRE Resource Directory", draft-ietf-core-
	resource-directory-11 (work in progress), July 2017.		resource-directory-13 (work in progress), March 2018.
	[I-D.ietf-core-senml]		[I-D.ietf-core-senml]
	Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.		Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
	Bormann, "Media Types for Sensor Measurement Lists		Bormann, "Media Types for Sensor Measurement Lists
	(SenML)", draft-ietf-core-senml-10 (work in progress),		(SenML)", draft-ietf-core-senml-13 (work in progress),
	July 2017.		March 2018.
	[OIC-Core]		[OIC-Core]
	"OIC Resource Type Specification v1.1.0", 2016,		"OIC Resource Type Specification v1.1.0", 2016,
	<https://openconnectivity.org/resources/specifications>.		<https://openconnectivity.org/resources/specifications>.
	[OIC-SmartHome]		[OIC-SmartHome]
	"OIC Smart Home Device Specification v1.1.0", 2016,		"OIC Smart Home Device Specification v1.1.0", 2016,
	<https://openconnectivity.org/resources/specifications>.		<https://openconnectivity.org/resources/specifications>.
	[OMA-TS-LWM2M]		[OMA-TS-LWM2M]
	"Lightweight Machine to Machine Technical Specification",		"Lightweight Machine to Machine Technical Specification",
	2016, <http://technical.openmobilealliance.org/Technical/		2016, <http://technical.openmobilealliance.org/Technical/
	technical-information/release-program/current-releases/		technical-information/release-program/current-releases/
	oma-lightweightm2m-v1-0>.		oma-lightweightm2m-v1-0>.
			[oneM2MTS0008]
			"TS 0008 v1.3.2 CoAP Protocol Binding", 2016,
			<http://www.onem2m.org/technical/published-documents>.
			[oneM2MTS0023]
			"TS 0023 v2.0.0 Home Appliances Information Model and
			Mapping", 2016,
			<http://www.onem2m.org/technical/published-documents>.
	[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, RFC		Resource Identifier (URI): Generic Syntax", STD 66,
	3986, DOI 10.17487/RFC3986, January 2005,		RFC 3986, DOI 10.17487/RFC3986, January 2005,
	<https://www.rfc-editor.org/info/rfc3986>.		<https://www.rfc-editor.org/info/rfc3986>.
	[RFC6573] Amundsen, M., "The Item and Collection Link Relations",		[RFC6573] Amundsen, M., "The Item and Collection Link Relations",
	RFC 6573, DOI 10.17487/RFC6573, April 2012,		RFC 6573, DOI 10.17487/RFC6573, April 2012,
	<https://www.rfc-editor.org/info/rfc6573>.		<https://www.rfc-editor.org/info/rfc6573>.
	[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer		[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
	Protocol (HTTP/1.1): Message Syntax and Routing", RFC		Protocol (HTTP/1.1): Message Syntax and Routing",
	7230, DOI 10.17487/RFC7230, June 2014, <https://www.rfc-		RFC 7230, DOI 10.17487/RFC7230, June 2014,
	editor.org/info/rfc7230>.		<https://www.rfc-editor.org/info/rfc7230>.
	[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained		[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
	Application Protocol (CoAP)", RFC 7252, DOI 10.17487/		Application Protocol (CoAP)", RFC 7252,
	RFC7252, June 2014, <https://www.rfc-editor.org/info/		DOI 10.17487/RFC7252, June 2014,
	rfc7252>.		<https://www.rfc-editor.org/info/rfc7252>.
	[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, <https://www.rfc-		DOI 10.17487/RFC7396, October 2014,
	editor.org/info/rfc7396>.		<https://www.rfc-editor.org/info/rfc7396>.
	[oneM2MTS0008]
	"TS 0008 v1.3.2 CoAP Protocol Binding", 2016,
	<http://www.onem2m.org/technical/published-documents>.
	[oneM2MTS0023]
	"TS 0023 v2.0.0 Home Appliances Information Model and
	Mapping", 2016,
	<http://www.onem2m.org/technical/published-documents>.
	Appendix A. Current Usage of Interfaces and Function Sets		Appendix A. Current Usage of Interfaces and Function Sets
	Editor's note: This appendix will be removed. It is only included		Editor's note: This appendix will be removed. It is only included
	for information.		for information.
	This appendix analyses the current landscape with regards the		This appendix analyses the current landscape with regards the
	definition and use of collections, interfaces and function sets/		definition and use of collections, interfaces and function sets/
	profiles. This should be considered when considering the scope of		profiles. This should be considered when considering the scope of
	this document.		this document.
End of changes. 60 change blocks.
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