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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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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Table of Contents

1. Introduction

As discussed in draft-lam-teas-usage-info-model-net-topology [I-D.lam-teas-usage-info-model-net-topology] 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 [OMG-UML-2.4] (as constrained by the ONF's UML Modeling Guidelines [ONF-TR-514]) to YANG (defined in RFC6020 [RFC6020] and YANG 1.1 [RFC7950]) 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 [RFC6020]

The following terms are defined in UML 2.4 [OMG-UML-2.4]

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         |
|   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".    |                       |                   |
+-------------------------------------------------------------------+
| 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    |
+-------------------------------------------------------------------+
| <<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          |                   |
+-------------------------------------------------------------------+
| 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")   |                   |
+-------------------------------------------------------------------+
| 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",     |
|                       | 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>>      |
|                       |                       | "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

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>>  |
|                       |                       | 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

+-------------------------------------------------------------------+
|               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. 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>>        |
|                       |                       | 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


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"     |
|                       |                       | 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.)                                  |
+-------------------------------------------------------------------+
| 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    |  |
|                       | +--------------------------------------+  |
|                       | | 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


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        |                   |
+-------------------------------------------------------------------+
| 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)

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"              |                   |
| 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

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:

  • 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 [RFC7223].
  • 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 [RFC7277].


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)

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 [ONF-TR-514] 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)

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 [RFC6020].

10. Informative References

[1] Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, October 2010.
[2] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 7223, DOI 10.17487/RFC7223, May 2014.
[3] Bjorklund, M., "A YANG Data Model for IP Management", RFC 7277, DOI 10.17487/RFC7277, June 2014.
[4] Bjorklund, M., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016.
[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", Internet-Draft draft-lam-teas-usage-info-model-net-topology-03, May 2016.
[6] OMG, "Unified Modeling Language (UML)", 2011.
[7] OMG, "ONF TR-514 v1.0 UML Modeling Guidelines", 2015.

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
Eve Varma Nokia USA EMail: eve.varma@nokia.com