draft-ietf-netmod-yang-usage-03.txt   draft-ietf-netmod-yang-usage-04.txt 
Internet Engineering Task Force A. Bierman Internet Engineering Task Force A. Bierman
Internet-Draft InterWorking Labs Internet-Draft InterWorking Labs
Intended status: Informational January 15, 2010 Intended status: Informational April 20, 2010
Expires: July 19, 2010 Expires: October 22, 2010
Guidelines for Authors and Reviewers of YANG Data Model Documents Guidelines for Authors and Reviewers of YANG Data Model Documents
draft-ietf-netmod-yang-usage-03 draft-ietf-netmod-yang-usage-04
Abstract Abstract
This memo provides guidelines for authors and reviewers of standards This memo provides guidelines for authors and reviewers of standards
track specifications containing YANG data model modules. Applicable track specifications containing YANG data model modules. Applicable
portions may be used as a basis for reviews of other YANG data model portions may be used as a basis for reviews of other YANG data model
documents. Recommendations and procedures are defined, which are documents. Recommendations and procedures are defined, which are
intended to increase interoperability and usability of NETCONF intended to increase interoperability and usability of NETCONF
implementations which utilize YANG data model modules. implementations which utilize YANG data model modules.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF 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), its areas, and its working groups. Note that Task Force (IETF). Note that other groups may also distribute
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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."
The list of current Internet-Drafts can be accessed at This Internet-Draft will expire on October 22, 2010.
http://www.ietf.org/ietf/1id-abstracts.txt.
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This Internet-Draft will expire on July 19, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 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
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 BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Notation . . . . . . . . . . . . . . . . . . 5 2.1. Requirements Notation . . . . . . . . . . . . . . . . . . 5
2.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . . . 5 2.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . . . 5
2.3. YANG Terms . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. YANG Terms . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. General Documentation Guidelines . . . . . . . . . . . . . . . 7 3. General Documentation Guidelines . . . . . . . . . . . . . . . 7
3.1. YANG Data Model Boilerplate Section . . . . . . . . . . . 7 3.1. Module Copyright . . . . . . . . . . . . . . . . . . . . . 7
3.2. Narrative Sections . . . . . . . . . . . . . . . . . . . . 7 3.2. Narrative Sections . . . . . . . . . . . . . . . . . . . . 7
3.3. Definitions Section . . . . . . . . . . . . . . . . . . . 8 3.3. Definitions Section . . . . . . . . . . . . . . . . . . . 8
3.4. Security Considerations Section . . . . . . . . . . . . . 8 3.4. Security Considerations Section . . . . . . . . . . . . . 8
3.5. IANA Considerations Section . . . . . . . . . . . . . . . 8 3.5. IANA Considerations Section . . . . . . . . . . . . . . . 8
3.5.1. Documents that Create a New Name Space . . . . . . . . 8 3.5.1. Documents that Create a New Name Space . . . . . . . . 8
3.5.2. Documents that Extend an Existing Name Space . . . . . 9 3.5.2. Documents that Extend an Existing Name Space . . . . . 9
3.6. Reference Sections . . . . . . . . . . . . . . . . . . . . 9 3.6. Reference Sections . . . . . . . . . . . . . . . . . . . . 9
3.7. Copyright Notices . . . . . . . . . . . . . . . . . . . . 9 3.7. Copyright Notices . . . . . . . . . . . . . . . . . . . . 9
3.8. Intellectual Property Section . . . . . . . . . . . . . . 9 3.8. Intellectual Property Section . . . . . . . . . . . . . . 9
4. YANG Usage Guidelines . . . . . . . . . . . . . . . . . . . . 10 4. YANG Usage Guidelines . . . . . . . . . . . . . . . . . . . . 10
skipping to change at page 3, line 36 skipping to change at page 3, line 36
4.2. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 10 4.2. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. Defaults . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.3. Defaults . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Conditional Statements . . . . . . . . . . . . . . . . . . 11 4.4. Conditional Statements . . . . . . . . . . . . . . . . . . 11
4.5. Lifecycle Management . . . . . . . . . . . . . . . . . . . 12 4.5. Lifecycle Management . . . . . . . . . . . . . . . . . . . 12
4.6. Header Contents . . . . . . . . . . . . . . . . . . . . . 12 4.6. Header Contents . . . . . . . . . . . . . . . . . . . . . 12
4.7. Temporary Namespace Assignments . . . . . . . . . . . . . 13 4.7. Temporary Namespace Assignments . . . . . . . . . . . . . 13
4.8. Top Level Database Objects . . . . . . . . . . . . . . . . 14 4.8. Top Level Database Objects . . . . . . . . . . . . . . . . 14
4.9. Data Types . . . . . . . . . . . . . . . . . . . . . . . . 15 4.9. Data Types . . . . . . . . . . . . . . . . . . . . . . . . 15
4.10. Reusable Type Definitions . . . . . . . . . . . . . . . . 15 4.10. Reusable Type Definitions . . . . . . . . . . . . . . . . 15
4.11. Object Definitions . . . . . . . . . . . . . . . . . . . . 16 4.11. Object Definitions . . . . . . . . . . . . . . . . . . . . 16
4.12. RPC Definitions . . . . . . . . . . . . . . . . . . . . . 17 4.12. Operation Definitions . . . . . . . . . . . . . . . . . . 17
4.13. Notification Definitions . . . . . . . . . . . . . . . . . 17 4.13. Notification Definitions . . . . . . . . . . . . . . . . . 17
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 19 6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . . 21 8.1. Normative References . . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . . 21 8.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Module Review Checklist . . . . . . . . . . . . . . . 22 Appendix A. Module Review Checklist . . . . . . . . . . . . . . . 22
Appendix B. YANG Module Template . . . . . . . . . . . . . . . . 24 Appendix B. YANG Module Template . . . . . . . . . . . . . . . . 24
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 27 Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 27
C.1. Changes from 00 to 01 . . . . . . . . . . . . . . . . . . 27 C.1. Changes from 03 to 04 . . . . . . . . . . . . . . . . . . 27
C.2. Changes from 01 to 02 . . . . . . . . . . . . . . . . . . 27 C.2. Changes from 02 to 03 . . . . . . . . . . . . . . . . . . 28
C.3. Changes from 02 to 03 . . . . . . . . . . . . . . . . . . 27 C.3. Changes from 01 to 02 . . . . . . . . . . . . . . . . . . 28
C.4. Changes from 00 to 01 . . . . . . . . . . . . . . . . . . 28
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 29 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 29
1. Introduction 1. Introduction
The standardization of network configuration interfaces for use with The standardization of network configuration interfaces for use with
the NETCONF [RFC4741] protocol requires a modular set of data models, the NETCONF [RFC4741] protocol requires a modular set of data models,
which can be reused and extended over time. which can be reused and extended over time.
This document defines a set of usage guidelines for standards track This document defines a set of usage guidelines for standards track
documents containing YANG [I-D.ietf-netmod-yang] data models. It is documents containing YANG [I-D.ietf-netmod-yang] data models. It is
similar to the MIB usage guidelines specification [RFC4181] in intent similar to the MIB usage guidelines specification [RFC4181] in intent
and structure. and structure.
Many YANG constructs are defined as optional to use, such as the Many YANG constructs are defined as optional to use, such as the
description clause. However, in order to maximize interoperability description clause. However, in order to maximize interoperability
of NETCONF implementations utilizing YANG data models, it is of NETCONF implementations utilizing YANG data models, it is
desirable to define a set of usage guidelines which may require a desirable to define a set of usage guidelines which may require a
higher level of compliance than the minimum level defined in the YANG higher level of compliance than the minimum level defined in the YANG
specification. specification.
The NETCONF stack can be conceptually partitioned into four layers.
Layer Example
+-------------+ +--------------------+ +-------------------+
(4) | Content | | Configuration data | | Notification data |
+-------------+ +--------------------+ +-------------------+
| | |
+-------------+ +-----------------+ |
(3) | Operations | | <edit-config> | |
+-------------+ +-----------------+ |
| | |
+-------------+ +--------------------+ +----------------+
(2) | Messages | | <rpc>, <rpc-reply> | | <notification> |
+-------------+ +--------------------+ +----------------+
| | |
+-------------+ +-----------------------------------------+
(1) | Secure | | SSH, TLS, BEEP/TLS, SOAP/HTTP/TLS, ... |
| Transports | | |
+-------------+ +-----------------------------------------+
Figure 1
This document defines usage guidelines related to the NETCONF This document defines usage guidelines related to the NETCONF
operations layer (3), and NETCONF content layer (4). operations layer, and NETCONF content layer, as defined in [RFC4741].
2. Terminology 2. Terminology
2.1. Requirements Notation 2.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
RFC 2119 language is used here to express the views of the NETMOD RFC 2119 language is used here to express the views of the NETMOD
working group regarding YANG module content. Yang modules complying working group regarding YANG module content. Yang modules complying
with this document will treat the RFC 2119 terminology as if it were with this document will treat the RFC 2119 terminology as if it were
describing best current practices. describing best current practices.
2.2. NETCONF Terms 2.2. NETCONF Terms
The following terms are defined in [RFC4741] and are not redefined The following terms are defined in [RFC4741] and are not redefined
here: here:
o application
o capabilities o capabilities
o client o client
o operation o operation
o RPC
o server o server
2.3. YANG Terms 2.3. YANG Terms
The following terms are defined in [I-D.ietf-netmod-yang] and are not The following terms are defined in [I-D.ietf-netmod-yang] and are not
redefined here: redefined here:
o data node o data node
o module o module
o submodule
o namespace o namespace
o submodule
o version o version
Note that the term 'module' may be used as a generic term for a YANG
module or submodule. When describing properties which are specific
to submodules, the term 'submodule' is used instead.
2.4. Terms 2.4. Terms
The following terms are used throughout this document: The following terms are used throughout this document:
o module: Generic term for a YANG data model module or submodule. published: A stable release of a module or submodule, usually
When describing properties which are specific to submodules, the
term 'YANG submodule', or simply 'submodule' is used instead.
o Published Document: A stable release of a module, usually
contained in an RFC. contained in an RFC.
o Unpublished Document: An unstable release of a module, usually unpublished: An unstable release of a module or submodule, usually
contained in an Internet Draft. contained in an Internet Draft.
3. General Documentation Guidelines 3. General Documentation Guidelines
YANG data model modules under review are likely to be contained in YANG data model modules under review are likely to be contained in
Internet Drafts. All guidelines for Internet Draft authors MUST be Internet Drafts. All guidelines for Internet Draft authors MUST be
followed. These guidelines are available online at: followed. These guidelines are available online at:
http://www.rfc-editor.org/rfc-editor/instructions2authors.txt http://www.rfc-editor.org/rfc-editor/instructions2authors.txt
The following sections MUST be present in an Internet Draft The following sections MUST be present in an Internet Draft
containing a module: containing a module:
o YANG data model boilerplate section o YANG data model boilerplate section
o Narrative sections o Narrative sections
o Definitions section o Definitions section
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o Narrative sections o Narrative sections
o Definitions section o Definitions section
o Security Considerations section o Security Considerations section
o IANA Considerations section o IANA Considerations section
o References section o References section
3.1. YANG Data Model Boilerplate Section 3.1. Module Copyright
This section MUST contain a verbatim copy of the latest approved The module description statement MUST contain the latest approved
Internet-Standard Management Framework boilerplate, which is IETF Trust Copyright statement, which is available on-line, in
available on-line, in section 4 of the Trust Legal Provisions (TLP) section 4 of the Trust Legal Provisions (TLP) document, at:
document, at: http://trustee.ietf.org/license-info/
Each YANG module contained within an Internet Draft or RPC MUST be http://trustee.ietf.org/license-info/
identified as a 'Code Component'. The strings '<CODE BEGINS>' and
'<CODE ENDS>' SHOULD be used to identify each Code Component. Each YANG module or submodule contained within an Internet Draft or
RFC MUST be identified as a 'Code Component'. The strings '<CODE
BEGINS>' and '<CODE ENDS>' SHOULD be used to identify each Code
Component.
3.2. Narrative Sections 3.2. Narrative Sections
The narrative part MUST include an overview section that describes The narrative part MUST include an overview section that describes
the scope and field of application of the module(s) defined by the the scope and field of application of the module(s) defined by the
specification and that specifies the relationship (if any) of these specification and that specifies the relationship (if any) of these
modules to other standards, particularly to standards containing modules to other standards, particularly to standards containing
other module modules. The narrative part SHOULD include one or more other module modules. The narrative part SHOULD include one or more
sections to briefly describe the structure of the modules defined in sections to briefly describe the structure of the modules defined in
the specification. the specification.
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This section contains the module(s) defined by the specification. This section contains the module(s) defined by the specification.
These modules MUST be written in YANG [I-D.ietf-netmod-yang]. These modules MUST be written in YANG [I-D.ietf-netmod-yang].
See Section 4 for guidelines on YANG usage. See Section 4 for guidelines on YANG usage.
3.4. Security Considerations Section 3.4. Security Considerations Section
Each specification that defines one or more modules MUST contain a Each specification that defines one or more modules MUST contain a
section that discusses security considerations relevant to those section that discusses security considerations relevant to those
modules. This section MUST be patterned after the latest approved modules. This section MUST be patterned after the latest approved
template (available at [ed: URL TBD]). template (available at http://www.ops.ietf.org/yang-security.html).
In particular, writable module objects that could be especially In particular, writable module objects that could be especially
disruptive if abused MUST be explicitly listed by name and the disruptive if abused MUST be explicitly listed by name and the
associated security risks MUST be spelled out; similarly, readable associated security risks MUST be spelled out; similarly, readable
module objects that contain especially sensitive information or that module objects that contain especially sensitive information or that
raise significant privacy concerns MUST be explicitly listed by name raise significant privacy concerns MUST be explicitly listed by name
and the reasons for the sensitivity/privacy concerns MUST be and the reasons for the sensitivity/privacy concerns MUST be
explained. explained.
3.5. IANA Considerations Section 3.5. IANA Considerations Section
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administered. administered.
Specifically, if any YANG module namespace statement value contained Specifically, if any YANG module namespace statement value contained
in the document is not already registered with IANA, then a new YANG in the document is not already registered with IANA, then a new YANG
Namespace registry entry must be requested from the IANA. The YANG Namespace registry entry must be requested from the IANA. The YANG
specification includes the procedure for this purpose in its IANA specification includes the procedure for this purpose in its IANA
Considerations section. Considerations section.
3.5.2. Documents that Extend an Existing Name Space 3.5.2. Documents that Extend an Existing Name Space
If an Internet-Draft defines any extensions to a YANG Namespace It is possible to extend an existing namespace using a YANG submodule
already administered by the IANA, then the document MUST include an which belongs to an existing module already administered by IANA. In
IANA Considerations section, specifies how the name space extension this case, the document containing the main module MUST be updated to
is to be administered. use the latest revision of the submodule.
Specifically, if any YANG submodule belongs-to value contained in the
document is associated with a module that contains a namespace
statement value equal to a YANG Namespace already administered by the
IANA, then the existing YANG Namespace must be updated to include the
new submodule.
3.6. Reference Sections 3.6. Reference Sections
For every import or include statement which appears in a module For every import or include statement which appears in a module
contained in the specification, which identifies a module in a contained in the specification, which identifies a module in a
separate document, a corresponding normative reference to that separate document, a corresponding normative reference to that
document MUST appear in the Normative References section. The document MUST appear in the Normative References section. The
reference MUST correspond to the specific module version actually reference MUST correspond to the specific module version actually
used within the specification. used within the specification.
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In order to promote interoperability and establish a set of practices In order to promote interoperability and establish a set of practices
based on previous experience, the following sections establish usage based on previous experience, the following sections establish usage
guidelines for specific YANG constructs. guidelines for specific YANG constructs.
Only guidelines which clarify or restrict the minimum conformance Only guidelines which clarify or restrict the minimum conformance
requirements are included here. requirements are included here.
4.1. Module Naming Conventions 4.1. Module Naming Conventions
Modules contained in standards track documents SHOULD be named with Modules contained in standards track documents SHOULD be named
the prefix 'ietf-'. Other types of modules MUST NOT use the 'ietf-' according to the guidelines in the IANA considerations section of
prefix string. [I-D.ietf-netmod-yang].
A distinctive word or acronym (e.g., protocol name or working group A distinctive word or acronym (e.g., protocol name or working group
acronym) SHOULD be used in the module name. If new definitions are acronym) SHOULD be used in the module name. If new definitions are
being defined to extend one or more existing modules, then the same being defined to extend one or more existing modules, then the same
word or acronym should be reused, instead of creating a new one. word or acronym should be reused, instead of creating a new one.
All published module names MUST be unique. All published module names MUST be unique.
Once a module name is published, it MUST not be reused, even if the Once a module name is published, it MUST not be reused, even if the
RFC containing the module is reclassified to 'Historic' status. RFC containing the module is reclassified to 'Historic' status.
4.2. Identifiers 4.2. Identifiers
Identifiers for modules, submodules, typedefs, groupings, data Identifiers for all published modules, submodules, typedefs,
objects, rpcs, and notifications MUST be between 1 and 64 characters groupings, data objects, operations, and notifications MUST be
in length. between 1 and 64 characters in length.
4.3. Defaults 4.3. Defaults
In general, it is suggested that sub-statements containing default In general, it is suggested that sub-statements containing default
values SHOULD NOT be present. For example, 'status current;', values SHOULD NOT be present. For example, 'status current;',
'config true;', 'mandatory false;', and 'max-elements unbounded;' are 'config true;', 'mandatory false;', and 'max-elements unbounded;' are
common defaults which would make the module difficult to read if used common defaults which would make the module difficult to read if used
everywhere they are allowed. everywhere they are allowed.
Instead, it is suggested that common statements SHOULD only be used Instead, it is suggested that common statements SHOULD only be used
when being set to a value other than the default value. when being set to a value other than the default value.
4.4. Conditional Statements 4.4. Conditional Statements
A module may be conceptually partitioned in several ways, using the A module may be conceptually partitioned in several ways, using the
'if-feature' and/or 'when' statements. In addition, NETCONF 'if-feature' and/or 'when' statements.
capabilities are designed to identify optional functionality.
Data model designers need to carefully consider all modularity Data model designers need to carefully consider all modularity
aspects, including the use of YANG conditional statements. aspects, including the use of YANG conditional statements.
Objects SHOULD NOT directly reference NETCONF capabilities, in order Objects SHOULD NOT directly reference NETCONF capabilities, in order
to specify optional behavior. Instead, a 'feature' statement SHOULD to specify optional behavior. Instead, a 'feature' statement SHOULD
be defined to represent the NETCONF capability, and the 'if-feature' be defined instead of a NETCONF capability, and the 'if-feature'
statement SHOULD be used within the object definition. statement SHOULD be used within the optional object definition.
If the condition associated with the desired semantics is not If the condition associated with the desired semantics is not
dependent on any particular instance value within the database, then dependent on any particular instance value within the database, then
an 'if-feature' statement SHOULD be used instead of a 'when' an 'if-feature' statement SHOULD be used instead of a 'when'
statement. statement.
All 'must' and 'when' statements MUST contain valid XPath. If any
name tests are present, they MUST contain valid module prefixes and
data node names. References to non-existent nodes are considered
invalid in YANG, even though they are permitted in XPath.
The 'attribute' and 'namespace' axis SHOULD NOT be used because the The 'attribute' and 'namespace' axis SHOULD NOT be used because the
associated XML node types are not supported in YANG, and may not be associated XML node types are not supported in YANG, and may not be
supported consistently across NETCONF server implementations. supported consistently across NETCONF server implementations.
The 'position' and 'last' functions SHOULD NOT be used. Also, the The 'position' and 'last' functions MAY be used with caution, within
'preceding', and 'following' axes SHOULD NOT be used. These a single server implementation. These functions may be useful in
some cases when processing user-ordered lists. A server is only
required to maintain the XML order of a user-ordered list or leaf-
list.
The 'preceding', and 'following' axes SHOULD NOT be used. These
constructs rely on XML document order within a NETCONF server constructs rely on XML document order within a NETCONF server
configuration database, which may not be supported consistently or configuration database, which may not be supported consistently or
produce reliable results across implementations. Predicate produce reliable results across implementations. Predicate
expressions based on static node properties (e.g., name, value, expressions based on static node properties (e.g., name, value,
ancestors, descendants) SHOULD be used instead. ancestors, descendants) SHOULD be used instead.
The 'preceding-sibling' and 'following-sibling' axes MAY be used, The 'preceding-sibling' and 'following-sibling' axes MAY be used,
with caution. A server is not required to maintain a persistent or with caution. A server is not required to maintain a persistent or
deterministic XML document order, which will affect use of these deterministic XML document order, which will affect use of these
axes. axes.
Implicit 'position' function calls within predicates SHOULD NOT be Implicit 'position' function calls within predicates SHOULD NOT be
used. (e.g., //chapter[42]). used. (e.g., //chapter[42]).
Data nodes which use the 'int64' and 'uint64' built-in type SHOULD Data nodes which use the 'int64' and 'uint64' built-in type MAY be
NOT be used within relational expressions. There are boundary used with caution, within relational expressions. There are boundary
conditions in which the translation from the YANG 64-bit type to an conditions in which the translation from the YANG 64-bit type to an
XPath number can cause incorrect results. XPath number can cause incorrect results. Specifically, an XPath
double precision floating point number cannot represent very large
positive or negative 64-bit numbers because it only provides a total
precision of 53 bits.
Data modelers need to be careful not to confuse the YANG value space Data modelers need to be careful not to confuse the YANG value space
and the XPath value space. The data types are not the same in both, and the XPath value space. The data types are not the same in both,
and conversion between YANG and XPath data types SHOULD be considered and conversion between YANG and XPath data types SHOULD be considered
carefully. carefully.
Explicit XPath data type conversions MAY be used (e.g., 'string', Explicit XPath data type conversions MAY be used (e.g., 'string',
'boolean', or 'number' functions), instead of implicit XPath data 'boolean', or 'number' functions), instead of implicit XPath data
type conversions. type conversions.
4.5. Lifecycle Management 4.5. Lifecycle Management
The status statement SHOULD NOT be present if its value is 'current'. The status statement SHOULD NOT be present if its value is 'current'.
It MUST be present if its value is 'deprecated' or 'obsolete'. It MUST be present if its value is 'deprecated' or 'obsolete'.
The module or submodule name MUST NOT be changed, once the document The module or submodule name MUST NOT be changed, once the document
containing the module or submodule is published. containing the module or submodule is published.
The module namespace URI value SHOULD NOT be changed, once the The module namespace URI value MUST NOT be changed, once the document
document containing the module is published. containing the module is published.
The revision-date sub-statement (within the imports statement) SHOULD The revision-date sub-statement (within the imports statement) SHOULD
be present if any groupings are used from the external module. be present if any groupings are used from the external module.
The revision-date sub-statement (within the include statement) SHOULD The revision-date sub-statement (within the include statement) SHOULD
be present if any groupings are used from the external sub-module. be present if any groupings are used from the external sub-module.
If submodules are used, then the document containing the main module
MUST be updated so that the main module revision date is equal or
more recent than the revision date of any submodule which is
(directly or indirectly) included by the main module.
4.6. Header Contents 4.6. Header Contents
For published modules, the namespace MUST be a globally unique URI, For published modules, the namespace MUST be a globally unique URI,
as defined in [RFC3986]. This value is usually assigned by the IANA. as defined in [RFC3986]. This value is usually assigned by the IANA.
The organization statement MUST be present. If the module is The organization statement MUST be present. If the module is
contained in a documented intended for standards-track status, then contained in a documented intended for standards-track status, then
the organization SHOULD be the IETF working group chartered to write the organization SHOULD be the IETF working group chartered to write
the document. the document.
The contact statement MUST be present. If the module is contained in The contact statement MUST be present. If the module is contained in
a documented intended for standards-track status, then the working a document intended for standards-track status, then the working
group WEB and mailing information MUST be present, and the document group WEB and mailing information MUST be present, and the document
author contact information SHOULD be present. In addition, the Area author contact information SHOULD be present. In addition, the Area
Director and other contact information MAY be present. Director and other contact information MAY be present.
The description statement MUST be present. If the module is The description statement MUST be present. The appropriate IETF
contained in an unpublished document, then the file name of this Trust Copyright text MUST be present, as described in Section 3.1.
document SHOULD be identified in the description statement. This
text MUST be removed when the document is published.
Modules are often extracted from their original documents and it is Modules are often extracted from their original documents and it is
useful for developers and operators to know how to find the original useful for developers and operators to know how to find the original
source document in a consistent manner. source document in a consistent manner.
The reference statement MUST be present. It MUST identify the
published document which contains the module.
If the module relies on information contained in other documents, If the module relies on information contained in other documents,
which are not the same documents implied by the import statements which are not the same documents implied by the import statements
present in the module, then these documents MUST be identified in the present in the module, then these documents MUST be identified in the
reference statement. reference statement.
A revision statement MUST be present for each published version of A revision statement MUST be present for each published version of
the module. The revision statement MUST have a reference
substatement. It MUST identify the published document which contains
the module. the module.
Each new revision MUST include a revision date which is higher than Each new revision MUST include a revision date which is higher than
any other revision date in the module. any other revision date in the module.
It is acceptable to reuse the same revision statement within It is acceptable to reuse the same revision statement within
unpublished versions (i.e., Internet Drafts), but the revision date unpublished versions (i.e., Internet Drafts), but the revision date
MUST be updated to a higher value each time the Internet Draft is re- MUST be updated to a higher value each time the Internet Draft is re-
published. published.
4.7. Temporary Namespace Assignments 4.7. Temporary Namespace Assignments
It is desirable to include only valid YANG modules in documents, It is desirable to include only valid YANG modules in documents,
whether they are published yet or not. whether they are published yet or not. This allows:
o allows the module to compile correctly instead of generating o the module to compile correctly instead of generating disruptive
disruptive fatal errors. fatal errors.
o allows early implementors to use the modules without picking a o early implementors to use the modules without picking a random
random value for this field. value for the XML namespace.
o allows early interoperability testing since independent o early interoperability testing since independent implementations
implementations will use the same namespace value. will use the same XML namespace value.
Until a URI is assigned by the IANA, a temporary namespace URI MUST Until a URI is assigned by the IANA, a temporary namespace URI MUST
be provided for the namespace statement in a YANG module. A value be provided for the namespace statement in a YANG module. A value
SHOULD be selected which is not likely to collide with other YANG SHOULD be selected which is not likely to collide with other YANG
namespaces. namespaces.
An unpublished module namespace statement value SHOULD include the A standard namespace statement value SHOULD have the following form:
field 'DRAFT-nn', where 'nn' is replaced by the current Internet
Draft number.
If the YANG module has been previously published, then the RPC being <URN prefix string>:<module-name>
updated needs to be identified. In this case, an unpublished module
namespace statement value SHOULD include the field
'DRAFT-XXXXBIS-nn', where 'XXXX' is replaced by the RFC number being
updated, and 'nn' is replaced by the current Internet Draft number.
A temporary namespace statement value SHOULD have the following form: The following URN prefix string SHOULD be used for published and
<URN prefix string>:<module-name>:<draft-field> unpublished YANG modules
The suggested URN prefix string that SHOULD be used is shown below. urn:ietf:params:xml:ns:yang:
This value will be defined by the IANA. urn:ietf:params:xml:ns:yang:
The following example URNs would be valid temporary namespace The following example URNs would be valid temporary namespace
statement values: statement values for standards-track modules:
urn:ietf:params:xml:ns:yang:ietf-netconf-partial-lock:DRAFT-09 urn:ietf:params:xml:ns:yang:ietf-netconf-partial-lock
urn:ietf:params:xml:ns:yang:ietf-netconf-state:DRAFT-07 urn:ietf:params:xml:ns:yang:ietf-netconf-state
urn:ietf:params:xml:ns:yang:ietf-netconf:DRAFT-4741BIS-01 urn:ietf:params:xml:ns:yang:ietf-netconf
Note that a different URN prefix string SHOULD be used for non-
standards track modules. The string SHOULD be selected according to
the guidelines in [I-D.ietf-netmod-yang].
The following examples of non-standards track modules are only
suggestions. There are no guidelines for this type of URN in this
document:
http://example.com/ns/example-interfaces
http://example.com/ns/example-system
4.8. Top Level Database Objects 4.8. Top Level Database Objects
There SHOULD only be one top-level data node defined in each YANG There SHOULD only be one top-level data node defined in each YANG
module. However, there MAY be more than one if needed. module. However, there MAY be more than one if needed.
The top-level data organization SHOULD be considered carefully, in The top-level data organization SHOULD be considered carefully, in
advance. Data model designers need to consider how the functionality advance. Data model designers need to consider how the functionality
for a given protocol or protocol family will grow over time. for a given protocol or protocol family will grow over time.
The names and data organization SHOULD reflect persistent The names and data organization SHOULD reflect persistent
information, such as the name of a protocol. The name of the working information, such as the name of a protocol. The name of the working
group SHOULD NOT be used because this may change over time. group SHOULD NOT be used because this may change over time.
A mandatory database object is defined as a node that a client must A mandatory database object is defined as a node that a client must
provide for the database to be valid. The server will not provide a provide for the database to be valid. The server will not provide a
value under any conditions. value under any conditions.
Top-level database objects MUST NOT be mandatory. Top-level database objects MUST NOT be mandatory. If a mandatory
node appears at the top-level, it will immediately cause the database
If a mandatory node appears at the top-level, it will immediately to be invalid. This can occur when the server boots or when a module
cause the database to be invalid. This can occur when the server is loaded dynamically at runtime.
boots or when a module is loaded dynamically at runtime.
Top level objects are declared in YANG as mandatory with the
mandatory statement or the min-elements statement. All nested non-
presence containers are transparent, so a mandatory node nested
within one or more non-presence containers causes the top-level
container to be considered mandatory.
4.9. Data Types 4.9. Data Types
Selection of an appropriate data type (i.e., built-in type, existing Selection of an appropriate data type (i.e., built-in type, existing
derived type, or new derived type) is very subjective and therefore derived type, or new derived type) is very subjective and therefore
few requirements can be specified on that subject. few requirements can be specified on that subject.
Data model designers SHOULD use the most appropriate built-in data Data model designers SHOULD use the most appropriate built-in data
type for the particular application. type for the particular application.
If extensibility of enumerated values is required, then the If extensibility of enumerated values is required, then the
identityref data type SHOULD be used instead of an enumeration or identityref data type SHOULD be used instead of an enumeration or
other built-in type. other built-in type.
For string data types, if a machine-readable pattern can be defined For string data types, if a machine-readable pattern can be defined
for the desired semantics, then one or more pattern statements SHOULD for the desired semantics, then one or more pattern statements SHOULD
be present. be present.
For string data types, if the length of the string is not required to For string data types, if the length of the string is required to
be unbounded in all implementations, then a length statement SHOULD bounded in all implementations, then a length statement SHOULD be
be present. present.
For string data types, object semantics SHOULD NOT rely on
preservation of leading and trailing whitespace characters.
For numeric data types, if the values allowed by the intended For numeric data types, if the values allowed by the intended
semantics are different than those allowed by the unbounded intrinsic semantics are different than those allowed by the unbounded intrinsic
data type (e.g., int32), then a range statement SHOULD be present. data type (e.g., int32), then a range statement SHOULD be present.
The signed numeric data types (i.e., 'int8', 'int16', 'int32', and The signed numeric data types (i.e., 'int8', 'int16', 'int32', and
'int64') SHOULD NOT be used unless negative values are allowed for 'int64') SHOULD NOT be used unless negative values are allowed for
the desired semantics. the desired semantics.
For enumeration or bits data types, the semantics for each enum or For enumeration or bits data types, the semantics for each enum or
skipping to change at page 16, line 46 skipping to change at page 17, line 4
o leaf o leaf
o leaf-list o leaf-list
o list o list
o choice o choice
o anyxml o anyxml
If the object semantics are defined in an external document, then a If the object semantics are defined in an external document, then a
reference statement SHOULD be present. reference statement SHOULD be present.
The 'anyxml' construct MUST NOT be used within configuration data. The 'anyxml' construct MAY be used with caution within configuration
data. This may be useful to represent an HTML banner for example.
However, this construct SHOULD NOT be used if other YANG data node
types can be used instead to represent the desired syntax and
semantics.
If there are referential integrity constraints associated with the If there are referential integrity constraints associated with the
desired semantics that can be represented with XPath, then one or desired semantics that can be represented with XPath, then one or
more must statements SHOULD be present. more must statements SHOULD be present.
For list and leaf-list objects, if the number of possible instances For list and leaf-list objects, if the number of possible instances
is not required to be unbounded for all implementations, then the is required to be bounded for all implementations, then the max-
max-elements statement SHOULD be present. elements statements SHOULD be present.
If any must or when statements are used within the object definition, If any must or when statements are used within the object definition,
then the object description statement SHOULD describe the purpose of then the object description statement SHOULD describe the purpose of
each one. each one.
4.12. RPC Definitions 4.12. Operation Definitions
The description statement MUST be present. The description statement MUST be present in 'rpc' statements
defining new operations.
If the RPC method semantics are defined in an external document, then If the operation semantics are defined in an external document, then
a reference statement SHOULD be present. a reference statement SHOULD be present.
If the RPC method impacts system behavior in some way, it SHOULD be If the operation impacts system behavior in some way, it SHOULD be
mentioned in the description statement. mentioned in the description statement.
If the RPC method is potentially harmful to system behavior in some If the operation is potentially harmful to system behavior in some
way, it MUST be mentioned in the Security Considerations section of way, it MUST be mentioned in the Security Considerations section of
the document. the document.
4.13. Notification Definitions 4.13. Notification Definitions
The description statement MUST be present. The description statement MUST be present.
If the notification semantics are defined in an external document, If the notification semantics are defined in an external document,
then a reference statement SHOULD be present. then a reference statement SHOULD be present.
skipping to change at page 21, line 21 skipping to change at page 21, line 21
[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, January 2005. RFC 3986, January 2005.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006. December 2006.
[I-D.ietf-netmod-yang] [I-D.ietf-netmod-yang]
Bjorklund, M., "YANG - A data modeling language for Bjorklund, M., "YANG - A data modeling language for
NETCONF", draft-ietf-netmod-yang-10 (work in progress), NETCONF", draft-ietf-netmod-yang-12 (work in progress),
January 2010. April 2010.
[I-D.ietf-netmod-yang-types] [I-D.ietf-netmod-yang-types]
Schoenwaelder, J., "Common YANG Data Types", Schoenwaelder, J., "Common YANG Data Types",
draft-ietf-netmod-yang-types-05 (work in progress), draft-ietf-netmod-yang-types-08 (work in progress),
December 2009. April 2010.
8.2. Informative References 8.2. Informative References
[RFC4181] Heard, C., "Guidelines for Authors and Reviewers of MIB [RFC4181] Heard, C., "Guidelines for Authors and Reviewers of MIB
Documents", BCP 111, RFC 4181, September 2005. Documents", BCP 111, RFC 4181, September 2005.
Appendix A. Module Review Checklist Appendix A. Module Review Checklist
This section is adapted from RFC 4181. This section is adapted from RFC 4181.
The purpose of a YANG module review is to review the YANG module both The purpose of a YANG module review is to review the YANG module both
for technical correctness and for adherence to IETF documentation for technical correctness and for adherence to IETF documentation
requirements. The following checklist may be helpful when reviewing requirements. The following checklist may be helpful when reviewing
a draft document: a draft document:
1. I-D Boilerplate -- verify that the draft contains the required 1. I-D Boilerplate -- verify that the draft contains the required
Internet-Draft boilerplate (see Internet-Draft boilerplate (see
http://www.ietf.org/ietf/1id-guidelines.txt), including the http://www.ietf.org/ietf/1id-guidelines.txt), including the
appropriate statement to permit publication as an RFC, and that appropriate statement to permit publication as an RFC, and that
I-D boilerplate does not contain references or section numbers. I-D boilerplate does not contain references or section numbers.
2. Abstract -- verify that the abstract does not contain 2. Abstract -- verify that the abstract does not contain references,
references, that it does not have a section number, and that its that it does not have a section number, and that its content
content follows the guidelines in follows the guidelines in
http://www.ietf.org/ietf/1id-guidelines.txt. http://www.ietf.org/ietf/1id-guidelines.txt.
3. YANG Module Boilerplate -- verify that the draft contains the 3. IETF Trust Copyright -- verify that the draft contains the latest
latest approved SNMP Network Management Framework boilerplate approved TLP boilerplate as described in Section 3.1.
from the OPS area web site
(http://www.ops.ietf.org/mib-boilerplate.html). [ed: real URL
TBD]
4. Security Considerations Section -- verify that the draft uses 4. Security Considerations Section -- verify that the draft uses the
the latest approved template from the OPS area web site latest approved template from the OPS area web site
(http://www.ops.ietf.org/mib-security.html) and that the (http://www.ops.ietf.org/yang-security.html) and that the
guidelines therein have been followed. guidelines therein have been followed.
5. IANA Considerations Section -- this section must always be 5. IANA Considerations Section -- this section must always be
present. If the draft requires no action from the IANA, ensure present. For each module within the document, ensure that the
that this is explicitly noted. If the draft requires URI values IANA Considerations section contains entries for the following
to be assigned, ensure that the IANA Considerations section IANA registries:
contains the information specified in [TBD] of these guidelines.
If the draft contains the initial version of an IANA-maintained
module, verify that the [TBD] invocation contains maintenance
instructions that comply with the requirements in RFC 2434. In
the latter case, the IANA Considerations section that will
appear in the RFC MUST contain a pointer to the actual IANA-
maintained module.
6. References -- verify that the references are properly divided XML Namespace Registry: Register the YANG module namespace.
between normative and informative references, that RFC 2119 is
included as a normative reference if the terminology defined
therein is used in the document, that all references required by
the boilerplate are present, that all YANG modules containing
imported items are cited as normative references, and that all
citations point to the most current RFCs unless there is a valid
reason to do otherwise (for example, it is OK to include an
informative reference to a previous version of a specification
to help explain a feature included for backward compatibility).
7. Copyright Notices -- verify that the draft contains an YANG Module Registry: Register the YANG module name, prefix,
abbreviated copyright notice in the description statement of namespace, and RFC number, according to the rules specified in
each YANG module or sub-module, and that it contains the full [I-D.ietf-netmod-yang].
copyright notice and disclaimer specified in Sections 5.4 and
5.5 of RFC 3978 at the end of the document. Make sure that the
correct year is used in all copyright dates.
8. IPR Notice -- if the draft does not contains a verbatim copy of 6. References -- verify that the references are properly divided
the IPR notice specified in Section 5 of RFC 3979, recommend between normative and informative references, that RFC 2119 is
that the IPR notice be included. included as a normative reference if the terminology defined
therein is used in the document, that all references required by
the boilerplate are present, that all YANG modules containing
imported items are cited as normative references, and that all
citations point to the most current RFCs unless there is a valid
reason to do otherwise (for example, it is OK to include an
informative reference to a previous version of a specification to
help explain a feature included for backward compatibility).
9. Other Issues -- check for any issues mentioned in 7. Copyright Notices -- verify that the draft contains an
http://www.ietf.org/ID-Checklist.html that are not covered abbreviated IETF Trust copyright notice in the description
elsewhere. statement of each YANG module or sub-module, and that it contains
the full IETF Trust copyright notice at the end of the document.
Make sure that the correct year is used in all copyright dates.
Use the approved text from the latest Trust Legal Provisions
(TLP) document, which can be found at:
10. Technical Content -- review the actual technical content for http://trustee.ietf.org/license-info/
compliance with the guidelines in this document. The use of a
YANG module compiler is recommended when checking for syntax 8. Other Issues -- check for any issues mentioned in
errors; see [YANG tool URL TBD] for more information. Checking http://www.ietf.org/ID-Checklist.html that are not covered
for correct syntax, however, is only part of the job. It is elsewhere.
just as important to actually read the YANG module document from
the point of view of a potential implementor. It is 9. Technical Content -- review the actual technical content for
particularly important to check that description statements are compliance with the guidelines in this document. The use of a
sufficiently clear and unambiguous to allow interoperable YANG module compiler is recommended when checking for syntax
implementations to be created. errors; see [YANG tool URL TBD] for more information. Checking
for correct syntax, however, is only part of the job. It is just
as important to actually read the YANG module document from the
point of view of a potential implementor. It is particularly
important to check that description statements are sufficiently
clear and unambiguous to allow interoperable implementations to
be created.
Appendix B. YANG Module Template Appendix B. YANG Module Template
<CODE BEGINS> file "ietf-template.yang" <CODE BEGINS> file "ietf-template.yang"
module ietf-template { module ietf-template {
// replace this string with a unique namespace URN value // replace this string with a unique namespace URN value
namespace namespace
"urn:ietf:params:xml:ns:yang:ietf-template:DRAFT-02"; "urn:ietf:params:xml:ns:yang:ietf-template:DRAFT-02";
skipping to change at page 24, line 44 skipping to change at page 24, line 44
Editor: your-name Editor: your-name
<mailto:your-email@example.com>"; <mailto:your-email@example.com>";
// replace the first sentence in this description statement. // replace the first sentence in this description statement.
// replace the copyright notice with the most recent // replace the copyright notice with the most recent
// version, if it has been updated since the publication // version, if it has been updated since the publication
// of this document // of this document
description description
"This module defines a template for other YANG modules. "This module defines a template for other YANG modules.
Copyright (c) 2009 IETF Trust and the persons identified as Copyright (c) 2010 IETF Trust and the persons identified as
the document authors. All rights reserved. the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or Redistribution and use in source and binary forms, with or
without modification, are permitted provided that the without modification, is permitted pursuant to, and subject
following conditions are met: to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
- Redistributions of source code must retain the above Relating to IETF Documents
copyright notice, this list of conditions and the (http://trustee.ietf.org/license-info).
following disclaimer.
- Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the
following disclaimer in the documentation and/or other
materials provided with the distribution.
- Neither the name of Internet Society, IETF or IETF
Trust, nor the names of specific contributors, may be
used to endorse or promote products derived from this
software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
CONTRIBUTORS 'AS IS' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
This version of this YANG module is part of RFC XXXX; see This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices."; the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this note // RFC Ed.: replace XXXX with actual RFC number and remove this note
reference "RFC XXXX"; reference "RFC XXXX";
// RFC Ed.: remove this note // RFC Ed.: remove this note
// Note: extracted from draft-ietf-netmod-yang-usage-02.txt // Note: extracted from draft-ietf-netmod-yang-usage-04.txt
// replace YYYY-MM-DD with a real date (year-month-day) // replace YYYY-MM-DD with a real date (year-month-day)
// here is an example revision date: 2009-08-12 // here is an example revision date: 2009-08-12
revision YYYY-MM-DD { revision YYYY-MM-DD {
description description
"Initial version"; "Initial version";
} }
// extension statements // extension statements
// feature statements // feature statements
// identity statements // identity statements
// typedef statements // typedef statements
skipping to change at page 26, line 30 skipping to change at page 26, line 4
// rpc statements // rpc statements
// notification statements // notification statements
// DO NOT put deviation statements in a published module // DO NOT put deviation statements in a published module
} }
<CODE ENDS> <CODE ENDS>
Figure 1
Figure 2
Appendix C. Change Log Appendix C. Change Log
C.1. Changes from 00 to 01 C.1. Changes from 03 to 04
o Added transport 'TLS' to figure 1. o Removed figure 1 to reduce duplication, just refer to 4741bis
draft.
o Added note about RFC 2119 terminology. o Fixed bugs and typos found in WGLC reviews.
o Corrected URL for instructions to authors. o Removed some guidelines and referring to YANG draft instead of
duplicating YANG rules here.
o Updated namespace procedures section. o Changed security guidelines so they refer to the IETF Trust TLP
instead of MIB-specific references.
o Updated guidelines on module contact, reference, and organization o Change temporary namespace guidelines so the DRAFT-XX and RFC-nnnn
statements. suffix strings are not used.
o Added note on use of preceding-sibling and following-sibling axes o Changed some MIB boilerplate so it refers to YANG boilerplate
in XPath expressions. instead.
o Added section on temporary namespace statement values. o Introduced dangling URL reference to online YANG security
guidelines
o Added section on top level database objects. http://www.ops.ietf.org/yang-security.html
o Added ietf-template.yang appendix. Text from Bert Wijnen will be completed soon and posted online,
and then this URL will be finalized.
C.2. Changes from 01 to 02 o Moved reference for identifying the source document inside the
each revision statement.
o Removed guideline about valid XPath since YANG already requires
valid XPath.
o Added guideline that strings should not rely on preservation of
leading and trailing whitespace characters.
o Relaxed some XPath and anyxml guidelines from SHOULD NOT or MUST
NOT to MAY use with caution.
o Updated the TLP text within the example module again.
o Reversed order of change log so most recent entries are first.
C.2. Changes from 02 to 03
o Updated figure 1 to align with 4741bis draft.
o Updated guidelines for import-by-revision and include-by-revision.
o Added file name to code begins convention in ietf-template module.
C.3. Changes from 01 to 02
o Updated figure 1 per mailing list comments. o Updated figure 1 per mailing list comments.
o Updated suggested organization to include the working group name. o Updated suggested organization to include the working group name.
o Updated ietf-template.yang to use new organization statement o Updated ietf-template.yang to use new organization statement
value. value.
o Updated Code Component requirements as per new TLP. o Updated Code Component requirements as per new TLP.
o Updated ietf-template.yang to use new Code Component begin and end o Updated ietf-template.yang to use new Code Component begin and end
markers. markers.
o Updated references to the TLP in a couple sections. o Updated references to the TLP in a couple sections.
o Change manager/agent terminology to client/server. o Change manager/agent terminology to client/server.
C.3. Changes from 02 to 03 C.4. Changes from 00 to 01
o Updated figure 1 to align with 4741bis draft. o Added transport 'TLS' to figure 1.
o Updated guidelines for import-by-revision and include-by-revision. o Added note about RFC 2119 terminology.
o Added file name to code begins convention in ietf-template module. o Corrected URL for instructions to authors.
o Updated namespace procedures section.
o Updated guidelines on module contact, reference, and organization
statements.
o Added note on use of preceding-sibling and following-sibling axes
in XPath expressions.
o Added section on temporary namespace statement values.
o Added section on top level database objects.
o Added ietf-template.yang appendix.
Author's Address Author's Address
Andy Bierman Andy Bierman
InterWorking Labs InterWorking Labs
Email: andyb@iwl.com Email: andyb@iwl.com
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