Internet Engineering Task Force A. Bierman
Internet-Draft InterWorking Labs
Intended status: Informational April 20, 2010
Expires: October 22, 2010
Guidelines for Authors and Reviewers of YANG Data Model Documents
draft-ietf-netmod-yang-usage-04
Abstract
This memo provides guidelines for authors and reviewers of standards
track specifications containing YANG data model modules. Applicable
portions may be used as a basis for reviews of other YANG data model
documents. Recommendations and procedures are defined, which are
intended to increase interoperability and usability of NETCONF
implementations which utilize YANG data model modules.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 22, 2010.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
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described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements Notation . . . . . . . . . . . . . . . . . . 5
2.2. NETCONF Terms . . . . . . . . . . . . . . . . . . . . . . 5
2.3. YANG Terms . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. General Documentation Guidelines . . . . . . . . . . . . . . . 7
3.1. Module Copyright . . . . . . . . . . . . . . . . . . . . . 7
3.2. Narrative Sections . . . . . . . . . . . . . . . . . . . . 7
3.3. Definitions Section . . . . . . . . . . . . . . . . . . . 8
3.4. Security Considerations Section . . . . . . . . . . . . . 8
3.5. IANA Considerations Section . . . . . . . . . . . . . . . 8
3.5.1. Documents that Create a New Name Space . . . . . . . . 8
3.5.2. Documents that Extend an Existing Name Space . . . . . 9
3.6. Reference Sections . . . . . . . . . . . . . . . . . . . . 9
3.7. Copyright Notices . . . . . . . . . . . . . . . . . . . . 9
3.8. Intellectual Property Section . . . . . . . . . . . . . . 9
4. YANG Usage Guidelines . . . . . . . . . . . . . . . . . . . . 10
4.1. Module Naming Conventions . . . . . . . . . . . . . . . . 10
4.2. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. Defaults . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.4. Conditional Statements . . . . . . . . . . . . . . . . . . 11
4.5. Lifecycle Management . . . . . . . . . . . . . . . . . . . 12
4.6. Header Contents . . . . . . . . . . . . . . . . . . . . . 12
4.7. Temporary Namespace Assignments . . . . . . . . . . . . . 13
4.8. Top Level Database Objects . . . . . . . . . . . . . . . . 14
4.9. Data Types . . . . . . . . . . . . . . . . . . . . . . . . 15
4.10. Reusable Type Definitions . . . . . . . . . . . . . . . . 15
4.11. Object Definitions . . . . . . . . . . . . . . . . . . . . 16
4.12. Operation Definitions . . . . . . . . . . . . . . . . . . 17
4.13. Notification Definitions . . . . . . . . . . . . . . . . . 17
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
6. Security Considerations . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. Normative References . . . . . . . . . . . . . . . . . . . 21
8.2. Informative References . . . . . . . . . . . . . . . . . . 21
Appendix A. Module Review Checklist . . . . . . . . . . . . . . . 22
Appendix B. YANG Module Template . . . . . . . . . . . . . . . . 24
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 27
C.1. Changes from 03 to 04 . . . . . . . . . . . . . . . . . . 27
C.2. Changes from 02 to 03 . . . . . . . . . . . . . . . . . . 28
C.3. Changes from 01 to 02 . . . . . . . . . . . . . . . . . . 28
C.4. Changes from 00 to 01 . . . . . . . . . . . . . . . . . . 28
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 29
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1. Introduction
The standardization of network configuration interfaces for use with
the NETCONF [RFC4741] protocol requires a modular set of data models,
which can be reused and extended over time.
This document defines a set of usage guidelines for standards track
documents containing YANG [I-D.ietf-netmod-yang] data models. It is
similar to the MIB usage guidelines specification [RFC4181] in intent
and structure.
Many YANG constructs are defined as optional to use, such as the
description clause. However, in order to maximize interoperability
of NETCONF implementations utilizing YANG data models, it is
desirable to define a set of usage guidelines which may require a
higher level of compliance than the minimum level defined in the YANG
specification.
This document defines usage guidelines related to the NETCONF
operations layer, and NETCONF content layer, as defined in [RFC4741].
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2. Terminology
2.1. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
RFC 2119 language is used here to express the views of the NETMOD
working group regarding YANG module content. Yang modules complying
with this document will treat the RFC 2119 terminology as if it were
describing best current practices.
2.2. NETCONF Terms
The following terms are defined in [RFC4741] and are not redefined
here:
o capabilities
o client
o operation
o server
2.3. YANG Terms
The following terms are defined in [I-D.ietf-netmod-yang] and are not
redefined here:
o data node
o module
o namespace
o submodule
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.
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2.4. Terms
The following terms are used throughout this document:
published: A stable release of a module or submodule, usually
contained in an RFC.
unpublished: An unstable release of a module or submodule, usually
contained in an Internet Draft.
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3. General Documentation Guidelines
YANG data model modules under review are likely to be contained in
Internet Drafts. All guidelines for Internet Draft authors MUST be
followed. These guidelines are available online at:
http://www.rfc-editor.org/rfc-editor/instructions2authors.txt
The following sections MUST be present in an Internet Draft
containing a module:
o YANG data model boilerplate section
o Narrative sections
o Definitions section
o Security Considerations section
o IANA Considerations section
o References section
3.1. Module Copyright
The module description statement MUST contain the latest approved
IETF Trust Copyright statement, which is available on-line, in
section 4 of the Trust Legal Provisions (TLP) document, at:
http://trustee.ietf.org/license-info/
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
The narrative part MUST include an overview section that describes
the scope and field of application of the module(s) defined by the
specification and that specifies the relationship (if any) of these
modules to other standards, particularly to standards containing
other module modules. The narrative part SHOULD include one or more
sections to briefly describe the structure of the modules defined in
the specification.
If the module(s) defined by the specification import definitions from
other modules (except for those defined in the YANG
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[I-D.ietf-netmod-yang] or YANG Types [I-D.ietf-netmod-yang-types]
documents) or are always implemented in conjunction with other
modules, then those facts MUST be noted in the overview section, as
MUST any special interpretations of objects in other modules.
3.3. Definitions Section
This section contains the module(s) defined by the specification.
These modules MUST be written in YANG [I-D.ietf-netmod-yang].
See Section 4 for guidelines on YANG usage.
3.4. Security Considerations Section
Each specification that defines one or more modules MUST contain a
section that discusses security considerations relevant to those
modules. This section MUST be patterned after the latest approved
template (available at http://www.ops.ietf.org/yang-security.html).
In particular, writable module objects that could be especially
disruptive if abused MUST be explicitly listed by name and the
associated security risks MUST be spelled out; similarly, readable
module objects that contain especially sensitive information or that
raise significant privacy concerns MUST be explicitly listed by name
and the reasons for the sensitivity/privacy concerns MUST be
explained.
3.5. IANA Considerations Section
In order to comply with IESG policy as set forth in
http://www.ietf.org/ID-Checklist.html, every Internet-Draft that is
submitted to the IESG for publication MUST contain an IANA
Considerations section. The requirements for this section vary
depending what actions are required of the IANA.
3.5.1. Documents that Create a New Name Space
If an Internet-Draft defines a new name space that is to be
administered by the IANA, then the document MUST include an IANA
Considerations section, that specifies how the name space is to be
administered.
Specifically, if any YANG module namespace statement value contained
in the document is not already registered with IANA, then a new YANG
Namespace registry entry must be requested from the IANA. The YANG
specification includes the procedure for this purpose in its IANA
Considerations section.
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3.5.2. Documents that Extend an Existing Name Space
It is possible to extend an existing namespace using a YANG submodule
which belongs to an existing module already administered by IANA. In
this case, the document containing the main module MUST be updated to
use the latest revision of the submodule.
3.6. Reference Sections
For every import or include statement which appears in a module
contained in the specification, which identifies a module in a
separate document, a corresponding normative reference to that
document MUST appear in the Normative References section. The
reference MUST correspond to the specific module version actually
used within the specification.
For every reference statement which appears in a module contained in
the specification, which identifies a separate document, a
corresponding normative reference to that document SHOULD appear in
the Normative References section. The reference SHOULD correspond to
the specific document version actually used within the specification.
3.7. Copyright Notices
The proper copyright notices MUST be present in the module
description statement. Refer to the IETF Trust Legal Provision for
the exact legal text that needs to be included.
3.8. Intellectual Property Section
The proper IPR statements MUST be present in the document, according
to the most current Internet Draft boilerplate. Refer to the IETF
Trust Legal Provision for the exact legal text that needs to be
included.
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4. YANG Usage Guidelines
In general, modules in IETF standards-track specifications MUST
comply with all syntactic and semantic requirements of YANG.
[I-D.ietf-netmod-yang]. The guidelines in this section are intended
to supplement the YANG specification, which is intended to define a
minimum set of conformance requirements.
In order to promote interoperability and establish a set of practices
based on previous experience, the following sections establish usage
guidelines for specific YANG constructs.
Only guidelines which clarify or restrict the minimum conformance
requirements are included here.
4.1. Module Naming Conventions
Modules contained in standards track documents SHOULD be named
according to the guidelines in the IANA considerations section of
[I-D.ietf-netmod-yang].
A distinctive word or acronym (e.g., protocol name or working group
acronym) SHOULD be used in the module name. If new definitions are
being defined to extend one or more existing modules, then the same
word or acronym should be reused, instead of creating a new one.
All published module names MUST be unique.
Once a module name is published, it MUST not be reused, even if the
RFC containing the module is reclassified to 'Historic' status.
4.2. Identifiers
Identifiers for all published modules, submodules, typedefs,
groupings, data objects, operations, and notifications MUST be
between 1 and 64 characters in length.
4.3. Defaults
In general, it is suggested that sub-statements containing default
values SHOULD NOT be present. For example, 'status current;',
'config true;', 'mandatory false;', and 'max-elements unbounded;' are
common defaults which would make the module difficult to read if used
everywhere they are allowed.
Instead, it is suggested that common statements SHOULD only be used
when being set to a value other than the default value.
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4.4. Conditional Statements
A module may be conceptually partitioned in several ways, using the
'if-feature' and/or 'when' statements.
Data model designers need to carefully consider all modularity
aspects, including the use of YANG conditional statements.
Objects SHOULD NOT directly reference NETCONF capabilities, in order
to specify optional behavior. Instead, a 'feature' statement SHOULD
be defined instead of a NETCONF capability, and the 'if-feature'
statement SHOULD be used within the optional object definition.
If the condition associated with the desired semantics is not
dependent on any particular instance value within the database, then
an 'if-feature' statement SHOULD be used instead of a 'when'
statement.
The 'attribute' and 'namespace' axis SHOULD NOT be used because the
associated XML node types are not supported in YANG, and may not be
supported consistently across NETCONF server implementations.
The 'position' and 'last' functions MAY be used with caution, within
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
configuration database, which may not be supported consistently or
produce reliable results across implementations. Predicate
expressions based on static node properties (e.g., name, value,
ancestors, descendants) SHOULD be used instead.
The 'preceding-sibling' and 'following-sibling' axes MAY be used,
with caution. A server is not required to maintain a persistent or
deterministic XML document order, which will affect use of these
axes.
Implicit 'position' function calls within predicates SHOULD NOT be
used. (e.g., //chapter[42]).
Data nodes which use the 'int64' and 'uint64' built-in type MAY be
used with caution, within relational expressions. There are boundary
conditions in which the translation from the YANG 64-bit type to an
XPath number can cause incorrect results. Specifically, an XPath
double precision floating point number cannot represent very large
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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
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
carefully.
Explicit XPath data type conversions MAY be used (e.g., 'string',
'boolean', or 'number' functions), instead of implicit XPath data
type conversions.
4.5. Lifecycle Management
The status statement SHOULD NOT be present if its value is 'current'.
It MUST be present if its value is 'deprecated' or 'obsolete'.
The module or submodule name MUST NOT be changed, once the document
containing the module or submodule is published.
The module namespace URI value MUST NOT be changed, once the document
containing the module is published.
The revision-date sub-statement (within the imports statement) SHOULD
be present if any groupings are used from the external module.
The revision-date sub-statement (within the include statement) SHOULD
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
For published modules, the namespace MUST be a globally unique URI,
as defined in [RFC3986]. This value is usually assigned by the IANA.
The organization statement MUST be present. If the module is
contained in a documented intended for standards-track status, then
the organization SHOULD be the IETF working group chartered to write
the document.
The contact statement MUST be present. If the module is contained in
a document intended for standards-track status, then the working
group WEB and mailing information MUST be present, and the document
author contact information SHOULD be present. In addition, the Area
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Director and other contact information MAY be present.
The description statement MUST be present. The appropriate IETF
Trust Copyright text MUST be present, as described in Section 3.1.
Modules are often extracted from their original documents and it is
useful for developers and operators to know how to find the original
source document in a consistent manner.
If the module relies on information contained in other documents,
which are not the same documents implied by the import statements
present in the module, then these documents MUST be identified in the
reference statement.
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.
Each new revision MUST include a revision date which is higher than
any other revision date in the module.
It is acceptable to reuse the same revision statement within
unpublished versions (i.e., Internet Drafts), but the revision date
MUST be updated to a higher value each time the Internet Draft is re-
published.
4.7. Temporary Namespace Assignments
It is desirable to include only valid YANG modules in documents,
whether they are published yet or not. This allows:
o the module to compile correctly instead of generating disruptive
fatal errors.
o early implementors to use the modules without picking a random
value for the XML namespace.
o early interoperability testing since independent implementations
will use the same XML namespace value.
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
SHOULD be selected which is not likely to collide with other YANG
namespaces.
A standard namespace statement value SHOULD have the following form:
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<URN prefix string>:<module-name>
The following URN prefix string SHOULD be used for published and
unpublished YANG modules
urn:ietf:params:xml:ns:yang:
The following example URNs would be valid temporary namespace
statement values for standards-track modules:
urn:ietf:params:xml:ns:yang:ietf-netconf-partial-lock
urn:ietf:params:xml:ns:yang:ietf-netconf-state
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
There SHOULD only be one top-level data node defined in each YANG
module. However, there MAY be more than one if needed.
The top-level data organization SHOULD be considered carefully, in
advance. Data model designers need to consider how the functionality
for a given protocol or protocol family will grow over time.
The names and data organization SHOULD reflect persistent
information, such as the name of a protocol. The name of the working
group SHOULD NOT be used because this may change over time.
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
value under any conditions.
Top-level database objects MUST NOT be mandatory. If a mandatory
node appears at the top-level, it will immediately cause the database
to be invalid. This can occur when the server boots or when a module
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is loaded dynamically at runtime.
4.9. Data Types
Selection of an appropriate data type (i.e., built-in type, existing
derived type, or new derived type) is very subjective and therefore
few requirements can be specified on that subject.
Data model designers SHOULD use the most appropriate built-in data
type for the particular application.
If extensibility of enumerated values is required, then the
identityref data type SHOULD be used instead of an enumeration or
other built-in type.
For string data types, if a machine-readable pattern can be defined
for the desired semantics, then one or more pattern statements SHOULD
be present.
For string data types, if the length of the string is required to
bounded in all implementations, then a length statement SHOULD be
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
semantics are different than those allowed by the unbounded intrinsic
data type (e.g., int32), then a range statement SHOULD be present.
The signed numeric data types (i.e., 'int8', 'int16', 'int32', and
'int64') SHOULD NOT be used unless negative values are allowed for
the desired semantics.
For enumeration or bits data types, the semantics for each enum or
bit SHOULD be documented. A separate description statement (within
each enum or bit statement) SHOULD be present.
4.10. Reusable Type Definitions
If an appropriate derived type exists in any standard module, such as
[I-D.ietf-netmod-yang-types], then it SHOULD be used instead of
defining a new derived type.
If an appropriate units identifier can be associated with the desired
semantics, then a units statement SHOULD be present.
If an appropriate default value can be associated with the desired
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semantics, then a default statement SHOULD be present.
If a significant number of derived types are defined, and it is
anticipated that these data types will be reused by multiple modules,
then these derived types SHOULD be contained in a separate module or
submodule, to allow easier reuse without unnecessary coupling.
The description statement MUST be present.
If the type definition semantics are defined in an external document,
then the reference statement SHOULD be present.
4.11. Object Definitions
The description statement MUST be present in the following body
statements:
o extension
o feature
o identity
o typedef
o grouping
o augment
o rpc
o notification
The description statement MUST be present in the following data
definition constructs:
o container
o leaf
o leaf-list
o list
o choice
o anyxml
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If the object semantics are defined in an external document, then a
reference statement SHOULD be present.
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
desired semantics that can be represented with XPath, then one or
more must statements SHOULD be present.
For list and leaf-list objects, if the number of possible instances
is required to be bounded for all implementations, then the max-
elements statements SHOULD be present.
If any must or when statements are used within the object definition,
then the object description statement SHOULD describe the purpose of
each one.
4.12. Operation Definitions
The description statement MUST be present in 'rpc' statements
defining new operations.
If the operation semantics are defined in an external document, then
a reference statement SHOULD be present.
If the operation impacts system behavior in some way, it SHOULD be
mentioned in the description statement.
If the operation is potentially harmful to system behavior in some
way, it MUST be mentioned in the Security Considerations section of
the document.
4.13. Notification Definitions
The description statement MUST be present.
If the notification semantics are defined in an external document,
then a reference statement SHOULD be present.
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5. IANA Considerations
There are no actions requested of IANA at this time.
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6. Security Considerations
This document defines documentation guidelines for NETCONF content
defined with the YANG data modeling language. It does not introduce
any new or increased security risks into the management system.
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7. Acknowledgments
The structure and contents of this document are adapted from
Guidelines for MIB Documents [RFC4181], by C. M. Heard.
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.
[I-D.ietf-netmod-yang]
Bjorklund, M., "YANG - A data modeling language for
NETCONF", draft-ietf-netmod-yang-12 (work in progress),
April 2010.
[I-D.ietf-netmod-yang-types]
Schoenwaelder, J., "Common YANG Data Types",
draft-ietf-netmod-yang-types-08 (work in progress),
April 2010.
8.2. Informative References
[RFC4181] Heard, C., "Guidelines for Authors and Reviewers of MIB
Documents", BCP 111, RFC 4181, September 2005.
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Appendix A. Module Review Checklist
This section is adapted from RFC 4181.
The purpose of a YANG module review is to review the YANG module both
for technical correctness and for adherence to IETF documentation
requirements. The following checklist may be helpful when reviewing
a draft document:
1. I-D Boilerplate -- verify that the draft contains the required
Internet-Draft boilerplate (see
http://www.ietf.org/ietf/1id-guidelines.txt), including the
appropriate statement to permit publication as an RFC, and that
I-D boilerplate does not contain references or section numbers.
2. Abstract -- verify that the abstract does not contain references,
that it does not have a section number, and that its content
follows the guidelines in
http://www.ietf.org/ietf/1id-guidelines.txt.
3. IETF Trust Copyright -- verify that the draft contains the latest
approved TLP boilerplate as described in Section 3.1.
4. Security Considerations Section -- verify that the draft uses the
latest approved template from the OPS area web site
(http://www.ops.ietf.org/yang-security.html) and that the
guidelines therein have been followed.
5. IANA Considerations Section -- this section must always be
present. For each module within the document, ensure that the
IANA Considerations section contains entries for the following
IANA registries:
XML Namespace Registry: Register the YANG module namespace.
YANG Module Registry: Register the YANG module name, prefix,
namespace, and RFC number, according to the rules specified in
[I-D.ietf-netmod-yang].
6. References -- verify that the references are properly divided
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
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help explain a feature included for backward compatibility).
7. Copyright Notices -- verify that the draft contains an
abbreviated IETF Trust copyright notice in the description
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:
http://trustee.ietf.org/license-info/
8. Other Issues -- check for any issues mentioned in
http://www.ietf.org/ID-Checklist.html that are not covered
elsewhere.
9. Technical Content -- review the actual technical content for
compliance with the guidelines in this document. The use of a
YANG module compiler is recommended when checking for syntax
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.
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Appendix B. YANG Module Template
<CODE BEGINS> file "ietf-template.yang"
module ietf-template {
// replace this string with a unique namespace URN value
namespace
"urn:ietf:params:xml:ns:yang:ietf-template:DRAFT-02";
// replace this string, and try to pick a unique prefix
prefix "temp";
// import statements here: e.g.,
// import ietf-yang-types { prefix yang; }
// import ietf-inet-types { prefix inet; }
// identify the IETF working group if applicable
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
// update this contact statement with your info
contact
"WG Web: <http://tools.ietf.org/wg/your-wg-name/>
WG List: <mailto:your-wg-name@ietf.org>
WG Chair: your-WG-chair
<mailto:your-WG-chair@example.com>
Editor: your-name
<mailto:your-email@example.com>";
// replace the first sentence in this description statement.
// replace the copyright notice with the most recent
// version, if it has been updated since the publication
// of this document
description
"This module defines a template for other YANG modules.
Copyright (c) 2010 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
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without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this note
reference "RFC XXXX";
// RFC Ed.: remove this note
// Note: extracted from draft-ietf-netmod-yang-usage-04.txt
// replace YYYY-MM-DD with a real date (year-month-day)
// here is an example revision date: 2009-08-12
revision YYYY-MM-DD {
description
"Initial version";
}
// extension statements
// feature statements
// identity statements
// typedef statements
// grouping statements
// data definition statements
// augment statements
// rpc statements
// notification statements
// DO NOT put deviation statements in a published module
}
<CODE ENDS>
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Figure 1
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Appendix C. Change Log
C.1. Changes from 03 to 04
o Removed figure 1 to reduce duplication, just refer to 4741bis
draft.
o Fixed bugs and typos found in WGLC reviews.
o Removed some guidelines and referring to YANG draft instead of
duplicating YANG rules here.
o Changed security guidelines so they refer to the IETF Trust TLP
instead of MIB-specific references.
o Change temporary namespace guidelines so the DRAFT-XX and RFC-nnnn
suffix strings are not used.
o Changed some MIB boilerplate so it refers to YANG boilerplate
instead.
o Introduced dangling URL reference to online YANG security
guidelines
http://www.ops.ietf.org/yang-security.html
Text from Bert Wijnen will be completed soon and posted online,
and then this URL will be finalized.
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.
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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 suggested organization to include the working group name.
o Updated ietf-template.yang to use new organization statement
value.
o Updated Code Component requirements as per new TLP.
o Updated ietf-template.yang to use new Code Component begin and end
markers.
o Updated references to the TLP in a couple sections.
o Change manager/agent terminology to client/server.
C.4. Changes from 00 to 01
o Added transport 'TLS' to figure 1.
o Added note about RFC 2119 terminology.
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.
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Author's Address
Andy Bierman
InterWorking Labs
Email: andyb@iwl.com
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