Internet DRAFT - draft-mansfield-netmod-uml-to-yang

draft-mansfield-netmod-uml-to-yang







NETMOD Working Group                                   S. Mansfield, Ed.
Internet-Draft                                             Ericsson Inc.
Intended status: Informational                                 B. Zeuner
Expires: April 30, 2017                              Deutsche Telekom AG
                                                                N. Davis
                                                                   Ciena
                                                                  Y. Yun
                                                               Fiberhome
                                                               Y. Tochio
                                                                 Fujitsu
                                                                  K. Lam
                                                                E. Varma
                                                                   Nokia
                                                        October 27, 2016


 Guidelines for Translation of UML Information Model to YANG Data Model
                 draft-mansfield-netmod-uml-to-yang-03

Abstract

   This document defines guidelines for translation of data modeled with
   UML to YANG including mapping of object classes, attributes, data
   types, associations, interfaces, operations and operation parameters,
   notifications, and lifecycle.

Status of This Memo

   This Internet-Draft is submitted 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/.

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   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 April 30, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Mapping Guidelines  . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Mapping Guideline Considerations  . . . . . . . . . . . .   4
     4.2.  Mapping of Object Classes . . . . . . . . . . . . . . . .   4
     4.3.  Mapping of Attributes . . . . . . . . . . . . . . . . . .   8
     4.4.  Mapping of Types  . . . . . . . . . . . . . . . . . . . .  11
       4.4.1.  Mapping of Primitive Types  . . . . . . . . . . . . .  12
       4.4.2.  Mapping of Complex Data Types . . . . . . . . . . . .  13
     4.5.  Mapping of Enumeration Types  . . . . . . . . . . . . . .  15
     4.6.  Mapping of Associations . . . . . . . . . . . . . . . . .  16
     4.7.  Mapping of Interfaces . . . . . . . . . . . . . . . . . .  17
     4.8.  Mapping of Operations . . . . . . . . . . . . . . . . . .  18
     4.9.  Mapping of Operation Parameters . . . . . . . . . . . . .  21
     4.10. Mapping of Notifications  . . . . . . . . . . . . . . . .  23
     4.11. Mapping of Lifecycle  . . . . . . . . . . . . . . . . . .  24
   5.  Mapping Patterns  . . . . . . . . . . . . . . . . . . . . . .  25
     5.1.  UML Recursion . . . . . . . . . . . . . . . . . . . . . .  25
       5.1.1.  Reference Based Approach  . . . . . . . . . . . . . .  25
     5.2.  UML Conditional Pacs  . . . . . . . . . . . . . . . . . .  25
     5.3.  XOR Relationship  . . . . . . . . . . . . . . . . . . . .  25
     5.4.  Choice Stereotype . . . . . . . . . . . . . . . . . . . .  26
     5.5.  Mapping of UML Support and Condition  . . . . . . . . . .  26
   6.  Mapping Basics  . . . . . . . . . . . . . . . . . . . . . . .  26
     6.1.  UML-YANG or XMI-YANG  . . . . . . . . . . . . . . . . . .  26
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  27
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  27
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  27
   10. Informative References  . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  28








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1.  Introduction

   As discussed in draft-lam-teas-usage-info-model-net-topology [5] a
   Data Model (DM) may be derived from an Information Model (IM).
   However, in order to assure a consistent and valid data modelling
   language representation that enables maximum interoperability,
   translation guidelines are required.  A set of translation rules also
   assists in development of automated tooling.

   This draft defines guidelines for translation of data modelled with
   UML [6] (as constrained by the ONF's UML Modeling Guidelines [7]) to
   YANG (defined in RFC6020 [1] and YANG 1.1 [4]) including mapping of
   object classes, attributes, data types, associations, interfaces,
   operations and operation parameters, notifications, and lifecycle.

2.  Terminology

   The following terms are defined in RFC6020 [1]

   o  anydata

   o  anyxml

   o  augment

   o  container

   o  data node

   o  identity

   o  instance identifier

   o  leaf

   o  leaf-list

   o  list

   o  module

   o  submodule

   The following terms are defined in UML 2.4 [6]

   o  association

   o  attribute



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   o  data type

   o  interface

   o  object class

   o  operation

   o  parameter

   o  signal (used to model notifications)

3.  Overview

   This document defines translation rules for all constructs used in a
   UML based IM to a data model using YANG.

   While some mapping rules are straightforward, an IM in UML uses some
   constructs that cannot be mapped directly to a DM using YANG and
   conventions are described to make the translation predictable.
   Additionally, in some cases multiple mapping approaches are possible
   and selection among these is also necessary to assure
   interoperability.

   Mapping guidelines for these constructs are provided in the following
   sections.

4.  Mapping Guidelines

4.1.  Mapping Guideline Considerations

   Where "??" is inserted in the table, it means that the specific
   mapping is for further study as it is either as yet unclear how to
   map the construct or that there are multiple ways of doing the
   mapping and a single one needs to be selected.

   A table will be included summarizing constructs in UML that do not
   directly map to YANG and where in this draft the associated
   guidelines for mapping these constructs will be provided.

4.2.  Mapping of Object Classes

   +-------------------------------------------------------------------+
   |                           Object Class                            |
   | - Real object classes having/inheriting at least one attribute    |
   |   identified as "partOfObjectKey" will be mapped to a "list"      |
   |   statement                                                       |
   | - Real object classes not having/inheriting any attribute         |



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   |   identified as "partOfObjectKey" will be mapped to a "container" |
   |   statement                                                       |
   | - Abstract object classes used for inheritance will be mapped     |
   |   to a "grouping" statement                                       |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | superclass(es)        | "grouping" statement  | Concrete          |
   |                       |                       | superclasses are  |
   |                       |                       | then mapped to    |
   |                       |                       | container/list    |
   |                       |                       | which uses these  |
   |                       |                       | groupings.        |
   +-------------------------------------------------------------------+
   | abstract              | "grouping" statement  | It is possible    |
   |                       |                       | that the          |
   |                       |                       | superclass or     |
   |                       |                       | abstract class    |
   |                       |                       | contains the key  |
   |                       |                       | attribute for the |
   |                       |                       | instantiated      |
   |                       |                       | subclass, this    |
   |                       |                       | requires the      |
   |                       |                       | creation of the   |
   |                       |                       | grouping but later|
   |                       |                       | when the subclass |
   |                       |                       | is instantiated   |
   |                       |                       | the key value must|
   |                       |                       | be identified from|
   |                       |                       | within the        |
   |                       |                       | grouping.         |
   +-------------------------------------------------------------------+
   | object identifier     | list::"key"           | It is possible    |
   |                       | substatement          | that the super-   |
   | Note: Attributes used |                       | class or abstract |
   | as object identifier  |                       | class contains the|
   | are defined in UML by |                       | key attribute for |
   | the attribute         |                       | the instantiated  |
   | property              |                       | subclass.         |
   | "partOfObjectKey".    |                       |                   |



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   +-------------------------------------------------------------------+
   | object identifier list|                       | The splitting of a|
   |                       |                       | list attribute    |
   | Does not appear in the|                       | (marked as key)   |
   | UML when mapping to   |                       | into a single key |
   | YANG.                 |                       | attribute and an  |
   |                       |                       | additional list   |
   |                       |                       | attribute will be |
   |                       |                       | done in UML during|
   |                       |                       | Pruning and       |
   |                       |                       | Refactoring.  i.e.|
   |                       |                       | The mapping tool  |
   |                       |                       | will never get a  |
   |                       |                       | list attribute    |
   |                       |                       | which is part of  |
   |                       |                       | the object        |
   |                       |                       | identifier.       |
   +-------------------------------------------------------------------+
   | objectCreationNotific-| "notification"        | Goes beyond the   |
   | ation                 | statement             | simple "a notific-|
   | [YES/NO/NA]           |                       | ation has to be   |
   |                       |                       | sent": a tool can |
   |                       |                       | construct the sig-|
   |                       |                       | ature of the noti-|
   |                       |                       | cation by reading |
   |                       |                       | the created       |
   |                       |                       | object.           |
   +-------------------------------------------------------------------+
   | objectDeletionNotific-| "notification"        | Goes beyond the   |
   | ation                 | statement             | simple "a notific-|
   | [YES/NO/NA]           |                       | ation has to be   |
   |                       |                       | sent": a tool can |
   |                       |                       | construct the sig-|
   |                       |                       | ature of the noti-|
   |                       |                       | cation by reading |
   |                       |                       | the deleted       |
   |                       |                       | object. (i.e. not |
   |                       |                       | necessary to      |
   |                       |                       | provide the       |
   |                       |                       | attributes of the |
   |                       |                       | deleted object).  |
   +-------------------------------------------------------------------+
   | muliplicity >1 on     | list::"min-elements"  | min-elements      |
   | association to the    | "max-elements"        |  default = 0      |
   | class                 | substatements         | max-elements      |
   |                       |                       |  default=unbounded|
   |                       |                       | mandatory         |
   |                       |                       |  default=false    |



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   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | Proxy Class           | "choice"              |                   |
   | XOR                   | substatement          |                   |
   +-------------------------------------------------------------------+
   | support               | "if-feature"          | Support and       |
   |                       | substatement          | condition belong  |
   +-----------------------+                       | together. If the  |
   | condition             |                       | "support" is cond-|
   |                       |                       | itional, then the |
   |                       |                       | "condition"       |
   |                       |                       | explains the cond-|
   |                       |                       | itions under which|
   |                       |                       | the class has to  |
   |                       |                       | be supported.     |
   +-------------------------------------------------------------------+
   | operation             | "action"              | YANG 1.0 supports |
   |                       | substatement          | only rpc -> add   |
   |                       |                       | prefix to the rpc |
   |                       |                       | name; i.e.        |
   |                       |                       | objectClass::rpc; |
   |                       |                       | "action" requires |
   |                       |                       | YANG 1.1          |
   +-------------------------------------------------------------------+
   | Conditional PACs      | container::presence"  |                   |
   |                       | substatement          |                   |



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   +-------------------------------------------------------------------+
   | constraint property   | list::"unique"        | UML is not able to|
   |                       | substatement          | define a group    |
   |                       |                       | of attributes to be
   |                       |                       | unique as YANG can|
   |                       |                       | do using the      |
   |                       |                       | "unique"          |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | {<constraint>}        | "when" substatement   |                   |
   +-------------------------------------------------------------------+

                    Figure 1: Mapping of Object Classes


   Figure 2: Example of Abstract Object Class Mapping (Available in PDF
                             or HTML versions)


   Figure 3: Example of Non-Abstract Object Class Mapping (Available in
                           PDF or HTML versions)

4.3.  Mapping of Attributes

   +-------------------------------------------------------------------+
   |       Attribute --> "leaf" (single) or "leaf list" (multiple)     |
   |                        statement                                  |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | type                  | "type" substatement   |                   |
   |                       | (built-in or derived) |                   |
   +-------------------------------------------------------------------+
   | readOnly              | "config" substatement | config            |
   |                       | (false)               | default = true    |
   +-------------------------------------------------------------------+
   | isOrdered             | "ordered-by"          | ordered-by        |
   |                       | substatement          | default = system  |
   |                       |("system" or "user")   |                   |
   +-------------------------------------------------------------------+



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   | isUnique              | No unique             | Only relevant for |
   |                       | sub-statement in      | multi-valued      |
   |                       | leaf-list             | attributes.       |
   +-------------------------------------------------------------------+
   | Multiplicity          | "mandatory" or        | min-elements      |
   | (carried in XMI as    | "min-elements" and    |  default = 0      |
   | lowerValue and        | "max-elements"        | max-elements      |
   | upperValue)           | substatements         |  default=unbounded|
   |                       | [0..1]=>no mapping    | mandatory         |
   |                       |   needed; is default  |  default=false    |
   |                       |   substatement=false  |                   |
   |                       | [1]=>mandatory        |                   |
   |                       |   substatement=true   |                   |
   |                       | [0..x]=> no mapping   |                   |
   |                       |   needed; is default  |                   |
   |                       | [1..x]=> min-elements |                   |
   |                       |   substatement = 1    |                   |
   |                       | [0..3]=> max-elements |                   |
   |                       |   substatement = 3    |                   |
   +-------------------------------------------------------------------+
   | defaultValue          | "default"             | If a default value|
   |                       | substatement          | exists and it is  |
   |                       |                       | the desired value,|
   |                       |                       | the parameter does|
   |                       |                       | not have to be    |
   |                       |                       | explicitly config-|
   |                       |                       | ured by the user. |
   +-------------------------------------------------------------------+
   | isInvariant           | "extension"           |                   |
   |                       | substatement ->       |                   |
   |                       | ompExt:isInvariant    |                   |
   +-------------------------------------------------------------------+
   | valueRange            | For string type:      | The tool should   |
   |                       |   "pattern" and/or    | provide a warning |
   |                       |   "length substatement| at the output of  |
   |                       | of "type" substatement| mapping process   |
   |                       | For integer and       | notifying when one|
   |                       |     decimal type:     | or more UML       |
   |                       |   "range" substatement| valueRange        |
   |                       | of "type" substatement| definitions are   |
   |                       | For all other typed   | contained in the  |
   |                       | attributes and for    | description       |
   |                       | string or integer or  | substatement of   |
   |                       | decimal typed         | the corresponding |
   |                       | attributes where the  | leaf or leaf-list.|
   |                       | UML definition is not | When the value of |
   |                       | compliant to YANG:    | "valueRange" is   |
   |                       | "description"         | "null", "NA",     |



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   |                       | substatement          | "See data type",  |
   |                       |                       | the tool ignores  |
   |                       |                       | it and doesn't    |
   |                       |                       | print out "range" |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | passedByReference     | if passedByReference =| Relevant only to  |
   |                       | true -> type leafref {| attributes that   |
   |                       | path "/<object>/      | have an object    |
   |                       | <objectidentifier>"}  | class defined as  |
   |                       |                       | their type.       |
   |                       | if passedByReference =|                   |
   |                       | false -> either "list"|                   |
   |                       | statement (key        |                   |
   |                       | property, multiple    |                   |
   |                       | instances) or         |                   |
   |                       | "container" statement(|                   |
   |                       | single instance)      |                   |
   +-------------------------------------------------------------------+
   | partOfObjectKey > 0   | list::"key"           | It is possible that
   |                       | substatement          | the (abstract)    |
   |                       |                       | superclass contains
   |                       |                       | the key attribute |
   |                       |                       | for the           |
   |                       |                       | instantiated      |
   |                       |                       | subclass.         |
   +-------------------------------------------------------------------+
   | unit                  | "units" substatement  |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |



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   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | support               | For conditional       | Support and       |
   |                       | support only:         | condition belong  |
   +-----------------------+                       | together. If the  |
   | condition             | "if-feature"          | "support" is cond-|
   |                       | substatement          | itional, then the |
   |                       |                       | "condition"       |
   |                       | "when" substatement if| explains the cond-|
   |                       | condition can be      | itions under which|
   |                       | formalized as XPath   | the class has to  |
   |                       | expression (i.e., it  | be supported.     |
   |                       | is conditioned by the |                   |
   |                       | value of another      |                   |
   |                       | attribute)            |                   |
   +-------------------------------------------------------------------+
   | error notfication??   | "must"                |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | {<constraint>}        | "when" substatement   |                   |
   +-------------------------------------------------------------------+

                      Figure 4: Mapping of Attributes


     Figure 5: Example of Attribute Mapping (Available in PDF or HTML
                                 versions)

4.4.  Mapping of Types

   +-------------------------------------------------------------------+
   |                             Types                                 |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | Primitive Type        | Built-In Type if      | e.g., Integer     |
   |                       | defined               |                   |
   +-------------------------------------------------------------------+
   | Complex Data Type     | "grouping" statement  | e.g., date-time   |
   |                       |                       |                   |
   +-------------------------------------------------------------------+
   | Enumeration           | "enum" statement      |                   |
   +-------------------------------------------------------------------+

                        Figure 6: Mapping of Types




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4.4.1.  Mapping of Primitive Types

   +-------------------------------------------------------------------+
   |               Primitive Type -> "typeDef" statement               |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | type                  | "type" substatement   |                   |
   |                       | (built-in type or     |                   |
   |                       | derived type)         |                   |
   +-------------------------------------------------------------------+
   | defaultValue          | "default" substatment | If a default value|
   |                       |                       | exists and it is  |
   |                       |                       | the desired value,|
   |                       |                       | the parameter does|
   |                       |                       | not have to be    |
   |                       |                       | explicitly        |
   |                       |                       | configured by the |
   |                       |                       | user. When the    |
   |                       |                       | value of          |
   |                       |                       | "defaultValue" is |
   |                       |                       | "NA", the tool    |
   |                       |                       | ignores it and    |
   |                       |                       | doesn't print out |
   |                       |                       | "default"         |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | unit                  | "units" substatement  |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |



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   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+

                   Figure 7: Mapping of Primitive Types

4.4.2.  Mapping of Complex Data Types



































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   +-------------------------------------------------------------------+
   |               Complex Data Type -> "grouping" statement           |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | not used              | "action" substatement |                   |
   +-------------------------------------------------------------------+
   | XOR                   | "choice"              |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | complex attribute     | "uses" statement      |                   |
   +-------------------------------------------------------------------+

                  Figure 8: Mapping of Complex Data Types

   Leaf and leaf-list can only use built-in types, typeDef types or
   enumerations in their type substatement; i.e., not groupings.



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   Complex data types with more than one item (e.g., name value pair)
   can only be defined using groupings.  Groupings can only be used by
   grouping, container and list statements.


    Figure 9: Example of Complex Data Type Mapping (Available in PDF or
                              HTML versions)

4.5.  Mapping of Enumeration Types

   +-------------------------------------------------------------------+
   |               Enumeration Type -> "enum" statement                |
   |       typedef for reusable (indirect usage) enumerations          |
   |                        identity statement?                        |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | literal name          | enum name             |                   |
   +-------------------------------------------------------------------+
   | literal integer       | "value"               |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | isLeaf = true         | "enum"                | UML definition "" |
   | isLeaf = false        | substatement          |                   |
   |                       | "identity"/"base"     |                   |
   |                       | pattern               |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |



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   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+

                  Figure 10: Mapping of Enumeration Types


    Figure 11: Example of Enumeration Type Mapping (Available in PDF or
                              HTML versions)

4.6.  Mapping of Associations

   +-------------------------------------------------------------------+
   |                          Associations                             |
   +-------------------------------------------------------------------+
   | UML Artifact          | YANG Artifact         | Comment           |
   +-------------------------------------------------------------------+
   | Inheritance           | abstract superclass:  | Multiple          |
   |                       | "grouping" statement  | inheritance can   |
   |                       |                       | also be mapped    |
   |                       | concrete superclass:  | using "groupings" |
   |                       | "augment" statement   | Need to define    |
   |                       |                       | when augment is   |
   |                       |                       | used.  Note:      |
   |                       |                       | Augmentation can  |
   |                       |                       | be conditional.   |
   +-------------------------------------------------------------------+
   | Composition with      | "container" statement | How to map "passed|
   | (aggregation=         | containing "list"     | by reference"??   |
   |    'composite')       | statement(s) (multiple|                   |
   | "passed by value"     | contained instances)  |                   |
   |                       | or "container" state- |                   |
   |                       | ment(s) (single       |                   |
   |                       | contained instances)  |                   |
   +-------------------------------------------------------------------+
   | Aggregation with      | "leafref" statement   | How to map "passed|
   | (aggregation='shared')|                       | by value"??       |
   | "passed by reference" |                       |                   |
   +-------------------------------------------------------------------+

                    Figure 12: Mapping of Associations



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    Figure 13: Association Mapping Example 1 (Available in PDF or HTML
                                 versions)


    Figure 14: Association Mapping Example 2 (Available in PDF or HTML
                                 versions)


    Figure 15: Association Mapping Example 3 (Available in PDF or HTML
                                 versions)


    Figure 16: Association Mapping Example 4 (Available in PDF or HTML
                                 versions)


    Figure 17: Association Mapping Example 5 (Available in PDF or HTML
                                 versions)

                     +-------------------------------------------------+
                     |                       UML                       |
                     +-------------------------------------------------+
                     | containment | association |     inheritance     |
   +-------------------------------------------------------------------+
   | YANG | nesting  |      X      |             |                     |
   |      +------------------------------------------------------------+
   |      | grouping |             |             |          X          |
   |      |          |             |             |abstract superclasses|
   |      +------------------------------------------------------------+
   |      | augment  |             |             |          X          |
   |      |          |             |             |concrete superclasses|
   |      +------------------------------------------------------------+
   |      | leafref  |             |      X      |                     |
   +-------------------------------------------------------------------+

                  Figure 18: Association Mapping Summary

4.7.  Mapping of Interfaces

   +-------------------------------------------------------------------+
   |                     UML Interface -> Container??                  |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |



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   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | abstract              | "grouping" statement  |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | support               | "if-feature"          | Support and       |
   |                       | substatement          | condition belong  |
   +-----------------------+                       | together. If the  |
   | condition             |                       | "support" is cond-|
   |                       |                       | itional, then the |
   |                       |                       | "condition"       |
   |                       |                       | explains the cond-|
   |                       |                       | itions under which|
   |                       |                       | the class has to  |
   |                       |                       | be supported.     |
   +-------------------------------------------------------------------+

         Figure 19: Mapping of Interfaces (grouping of operations

4.8.  Mapping of Operations

   +-------------------------------------------------------------------+
   |             Operation -> "action" and "rpc" statements            |
   | (RFC 6020:  The difference between an action and an rpc is that an|
   | action is tied to a node in the data tree, whereas an rpc is      |
   | associated at the module level.)                                  |



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   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | pre-condition         | "extension"           | RFC 6020; During  |
   |                       | substatement ->       | the NETCONF       |
   |                       | ompExt:preCondition   | <edit-config> pro-|
   |                       |                       | cessing errors are|
   |                       |                       | already sent for: |
   |                       |                       | - Delete requests |
   |                       |                       |   for non-existent|
   |                       |                       |   data.           |
   |                       |                       | - Create requests |
   |                       |                       |   for existing    |
   |                       |                       |   data.           |
   |                       |                       | - Insert requests |
   |                       |                       |   with "before" or|
   |                       |                       |   "after" para-   |
   |                       |                       |   meters that do  |
   |                       |                       |   not exist.      |
   +-------------------------------------------------------------------+
   | post-condition        | "extension"           |                   |
   |                       | substatement          |                   |
   |                       | ompExt:postCondition  |                   |
   +-------------------------------------------------------------------+
   | input parameter       | "input" substatement  |                   |
   +-------------------------------------------------------------------+
   | output parameter      | "output" substatement |                   |
   +-------------------------------------------------------------------+
   | operation exceptions  | "extension"           |                   |
   |                       | substatement          |                   |
   | Internal Error        | ompExt:operationExceptions                |
   | Unable to Comply      |                                           |
   | Comm Loss             | +--------------------------------------+  |
   | Invalid Input         | | error-tag        | error-app-tag     |  |
   | Not Implemented       | +--------------------------------------+  |
   | Duplicate             | | operation-failed | too-many-elements |  |
   | Entity Not Found      | |                  | too-few-elements  |  |
   | Object In Use         | |                  | must-violation    |  |
   | Capacity Exceeded     | +--------------------------------------+  |
   | Not In Valid State    | | data-missing     | instance-required |  |
   | Access Denied         | |                  | missing-choice    |  |
   |                       | +--------------------------------------+  |



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   |                       | | bad-attribute    | missing-instance  |  |
   |                       | +--------------------------------------+  |
   +-------------------------------------------------------------------+
   | isOperationIdempotent | "extension"           |                   |
   |                       | substatement          |                   |
   |                       | ompExt:isOperationIdempotent              |
   +-------------------------------------------------------------------+
   | isAtomic              | "extension"           | Necessary?? Not in|
   |                       | substatement          | UML Guidelines    |
   |                       | ompExt:isAtomic       | (TR-514); needs to|
   |                       |                       | be added??        |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | support               | "if-feature"          | Support and       |
   |                       | substatement          | condition belong  |
   +-----------------------+                       | together. If the  |
   | condition             |                       | "support" is cond-|
   |                       |                       | itional, then the |
   |                       |                       | "condition"       |
   |                       |                       | explains the cond-|
   |                       |                       | itions under which|
   |                       |                       | the class has to  |
   |                       |                       | be supported.     |
   +-------------------------------------------------------------------+

                     Figure 20: Mapping of Operations



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      Figure 21: Operation Mapping Example (Available in PDF or HTML
                                 versions)

4.9.  Mapping of Operation Parameters

   +-------------------------------------------------------------------+
   |                      Operation Parameters                         |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | direction             | "input" or "output"   |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | type                  | see mapping of        |                   |
   +-----------------------| attribute types       |-------------------+
   | isOrdered             | (grouping, leaf,      |                   |
   +-----------------------|  leaf-list, list,     |-------------------+
   | multiplicity          |  typedef, uses)       |                   |
   +-----------------------|                       |-------------------+
   | defaultValue          |                       |                   |
   +-----------------------|                       |-------------------+
   | valueRange            |                       |                   |
   +-------------------------------------------------------------------+
   | passedByReference     | if passedByReference =| Relevant only to  |
   |                       | true -> type leafref {| attributes that   |
   |                       | path "/<object>/      | have an object    |
   |                       | <objectidentifier>"}  | class defined as  |
   |                       |                       | their type.       |
   |                       | if passedByReference =|                   |
   |                       | false -> either "list"|                   |
   |                       | statement (key        |                   |
   |                       | property, multiple    |                   |
   |                       | instances) or         |                   |
   |                       | "container" statement(|                   |
   |                       | single instance)      |                   |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |



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   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | support               | "if-feature"          | Support and       |
   |                       | substatement not      | condition belong  |
   +-----------------------+ defined for input and | together. If the  |
   | condition             | output substatements  | "support" is cond-|
   |                       | in YANG??             | itional, then the |
   |                       |                       | "condition"       |
   |                       |                       | explains the cond-|
   |                       |                       | itions under which|
   |                       |                       | the class has to  |
   |                       |                       | be supported.     |
   +-------------------------------------------------------------------+
   | XOR                   | "choice"              |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | error notification??  | "must"                |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | complex parameter     | "uses"                |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+

                Figure 22: Mapping of Operation Parameters


      Figure 23: Parameter Mapping Example (Available in PDF or HTML
                                 versions)








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4.10.  Mapping of Notifications

   +-------------------------------------------------------------------+
   |      Signal "grouping" statement -> "notification" statement      |
   +-------------------------------------------------------------------+
   | documentation         | "description"         | Multiple "applied |
   | "Applied comments"    | substatement          | comments" defined |
   | (carried in XMI as    |                       | in UML, need to be|
   |  "ownedComment")      |                       | collapsed into a  |
   |                       |                       | single            |
   |                       |                       | "description"     |
   |                       |                       | substatement.     |
   +-------------------------------------------------------------------+
   | <<Reference>>         | "reference"           |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | <<Example>>           | Ignore Example        |                   |
   |                       | elements and all      |                   |
   |                       | composed parts        |                   |
   +-------------------------------------------------------------------+
   | lifecycleState        | "status"              | <<UML>> -> "YANG" |
   |                       | substatement          | <<Deprecated>>    |
   |                       |                       | "deprecated",     |
   |                       |                       | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+
   | support               | "if-feature"          | Support and       |
   |                       | substatement          | condition belong  |
   +-----------------------+                       | together. If the  |
   | condition             |                       | "support" is cond-|
   |                       |                       | itional, then the |
   |                       |                       | "condition"       |
   |                       |                       | explains the cond-|
   |                       |                       | itions under which|
   |                       |                       | the class has to  |
   |                       |                       | be supported.     |
   +-------------------------------------------------------------------+
   | Proxy Class           | "choice"              |                   |



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   | XOR                   | substatement          |                   |
   +-------------------------------------------------------------------+
   | error notification??  | "must"                |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+
   | attributes            | see mapping of        |                   |
   |                       | attribute types       |                   |
   |                       | (grouping, leaf,      |                   |
   |                       |  leaf-list, container,|                   |
   |                       |  list, typedef, uses) |                   |
   +-------------------------------------------------------------------+
   | complex attribute     | "uses"                |                   |
   |                       | substatement          |                   |
   +-------------------------------------------------------------------+

                    Figure 24: Mapping of Notifications


     Figure 25: Notification Mapping Example (Available in PDF or HTML
                                 versions)

4.11.  Mapping of Lifecycle

   +-------------------------------------------------------------------+
   |                          UML Lifecycle                            |
   +-------------------------------------------------------------------+
   | lifecycle stereotypes | "status"              | <<UML>> -> "YANG" |
   |                       | substatement or       | <<Deprecated>>    |
   |                       | "description"         | "deprecated",     |
   |                       | substatement          | <<Experimental>>  |
   |                       |                       | description,      |
   |                       |                       | <<Faulty>>        |
   |                       |                       | description,      |
   |                       |                       |<<LikelyToChange>> |
   |                       |                       | description,      |
   |                       |                       | <<Mature>>        |
   |                       |                       | "current",        |
   |                       |                       | <<Obsolete>>      |
   |                       |                       | "obsolete",       |
   |                       |                       | <<Preliminary>>   |
   |                       |                       | description       |
   +-------------------------------------------------------------------+

                      Figure 26: Mapping of Lifecycle







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5.  Mapping Patterns

5.1.  UML Recursion

   As YANG defines hierarchical data store, any instances that need to
   store recursive containment will require translation.  A mapping
   between object-oriented store and a hierarchical store is possible;
   however, there is more than one option:

   o  Reference Based Approach approach - have a flat list of objects,
      where the objects are linked into a hierarchy using references.
      An example of a two-way navigable approach is in RFC7223 [2].

   o  Assume some specific number of "recursions"; i.e., specify some
      default number of recursion levels, and define a configurable
      parameter to allow changing the number of levels.

5.1.1.  Reference Based Approach


     Figure 27: Recursion Mapping Example 1 (Available in PDF or HTML
                                 versions)


     Figure 28: Recursion Mapping Example 2 (Available in PDF or HTML
                                 versions)

5.2.  UML Conditional Pacs

   Use the "presence" property of the container statement?

   Note: An example of this usage is given in the "Data nodes for the
   operational state of IP on interfaces." within ietf-ip.yang RFC7277
   [3].


   Figure 29: Mapping of Conditional Packages (Available in PDF or HTML
                                 versions)

5.3.  XOR Relationship

   The associations related by the "xor" constraint are mapped to the
   "choice" property of the container/list statement.


   Figure 30: XOR Relationship Mapping Example (Available in PDF or HTML
                                 versions)




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5.4.  Choice Stereotype

   The choice sterotype can be associated in UML to a class or a data
   type.  The class or a data type which is annotated with the choice
   sterotype represents one of a set of classes/data types.  This
   pattern is mapped to the "choice" property of the container/list/
   grouping statement.


      Figure 31: Choice Stereotype Example (Available in PDF or HTML
                                 versions)

5.5.  Mapping of UML Support and Condition

   The UML Modeling Guidelines [7] define support and condition for all
   UML artifacts (M - Mandatory, O - Optional, C - Conditional, CM -
   Conditional-Mandatory, CO - Conditional-Optional).  Support qualifies
   the support of the artifact at the management interface.  Condition
   contains the condition for the condition-related support qualifiers.

   M - Mandatory maps to the "mandatory" substatement in choice and leaf
   or to the "min-elements" substatement in leaf-list and list.

   O - Optional need not be mapped since the per default the "mandatory"
   and "min-elements" substaments define optional.

   All conditional UML support qualifiers are mapped to the "if-feature"
   substatement.


   Figure 32: Support and Condition Mapping Example (Available in PDF or
                              HTML versions)

6.  Mapping Basics

6.1.  UML-YANG or XMI-YANG


     Figure 33: Example UML to YANG Mapping (Available in PDF or HTML
                                 versions)


   Figure 34: Example XMI (Papyrus) to YANG Mapping (Available in PDF or
                              HTML versions)







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7.  Acknowledgements

8.  IANA Considerations

   This memo includes no request to IANA.

9.  Security Considerations

   This document defines defines guidelines for translation of data
   modeled with UML to YANG.  As such, it doesn't contribute any new
   security issues beyond those discussed in Sec. 16 of RFC6020 [1].

10.  Informative References

   [1]        Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <http://www.rfc-editor.org/info/rfc6020>.

   [2]        Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <http://www.rfc-editor.org/info/rfc7223>.

   [3]        Bjorklund, M., "A YANG Data Model for IP Management",
              RFC 7277, DOI 10.17487/RFC7277, June 2014,
              <http://www.rfc-editor.org/info/rfc7277>.

   [4]        Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <http://www.rfc-editor.org/info/rfc7950>.

   [5]        Lam, H., Varma, E., Doolan, P., Davis, N., Zeuner, B.,
              Betts, M., Busi, I., Mansfield, S., Vilata, R., and V.
              Lopezalvarez, "Usage of IM for network topology to support
              TE Topology YANG Module Development", draft-lam-teas-
              usage-info-model-net-topology-03 (work in progress), May
              2016.

   [6]        OMG, "Unified Modeling Language (UML)", 2011,
              <http://www.omg.org/spec/UML/2.4/>.

   [7]        OMG, "ONF TR-514 v1.0 UML Modeling Guidelines", 2015,
              <https://www.opennetworking.org/images/stories/downloads/
              sdn-resources/technical-reports/
              UML_Modeling_Guidelines_V1.0.pdf>.






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Authors' Addresses

   Scott Mansfield (editor)
   Ericsson Inc.
   USA

   Phone: +1 724 931 9316
   Email: scott.mansfield@ericsson.com


   Bernd Zeuner
   Deutsche Telekom AG
   Heinrich-Hertz-Str, 3-7
   Darmstadt  64295
   Germany

   Phone: +49 6151 58-12086
   Email: b.zeuner@telekom.de


   Nigel Davis
   Ciena
   United Kingdom

   Email: ndavis@ciena.com


   Yun Xiang
   Fiberhome
   China

   Email: yunxig@fiberhome.com.cn


   Yuji Tochio
   Fujitsu
   Japan

   Email: tochio@jp.fujitsu.com


   Hing-Kam Lam
   Nokia
   USA

   Phone: +1 732 331 3476
   Email: kam.lam@nokia.com




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   Eve Varma
   Nokia
   USA

   Email: eve.varma@nokia.com














































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