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Operations and Management NETMOD Working Group UML Information modeling 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.

As discussed in draft-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 (as constrained by the ONF's UML Modeling Guidelines) to YANG (defined in RFC6020 and YANG Update) including mapping of object classes, attributes, data types, associations, interfaces, operations and operation parameters, notifications, and lifecycle.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

The following terms are defined in RFC6020 anydata anyxml augment container data node identity instance identifier leaf leaf-list list module submodule The following terms are defined in UML 2.4 association attribute data type interface object class operation parameter signal (used to model notifications)

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.

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.

"list" statement (key property) or | | "container" statement | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | superclass(es) | ?? | | +-------------------------------------------------------------------+ | abstract | abstract: "container" | | | | not abstract: "list" | | +-------------------------------------------------------------------+ | objectCreationNotific-| ?? | | | ation | | | +-------------------------------------------------------------------+ | objectDeletionNotific-| ?? | | | ation | | | +-------------------------------------------------------------------+ | support | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | condition | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | operation | "action" | | | | substatement | | +-------------------------------------------------------------------+ | XOR | "choice" | | | | substatement | | +-------------------------------------------------------------------+ | ?? | "config" | | | | substatement | | +-------------------------------------------------------------------+ | error notfication? | "must" | | | | substatement | | +-------------------------------------------------------------------+ | object identifier | list::"key" | | | | substatement | | +-------------------------------------------------------------------+ | ?? | list::"min-elements" | min-elements | | | "max-elements" | default = 0 | | | substatements | max-elements | | | | default=unbounded| | | | mandatory | | | | default=false | +-------------------------------------------------------------------+ | Conditional PACs | container::presence" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current" | | | substatement | "deprecated" | | | | "obsolete" | | | | default="current"| +-------------------------------------------------------------------+ | ?? | list::"unique" | | | | substatement | | +-------------------------------------------------------------------+ | complex attribute | "uses" substatement | | +-------------------------------------------------------------------+ | {} | "when" substatement | | +-------------------------------------------------------------------+ ]]>

"leaf" (single) or "leaf list" (multiple) | | statement | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | type | "type" substatement | | | | (built-in or derived) | | +-------------------------------------------------------------------+ | readOnly | "config" substatement | | | | (false) | | +-------------------------------------------------------------------+ | isOrdered | "ordered-by" | | | | substatement | | | |("system" or "user") | | +-------------------------------------------------------------------+ | multiplicity | "min-elements" and | min-elements | | | "max-elements" | default = 0 | | | substatements | max-elements | | | [0..x]=>mandatory | default=unbounded| | | substatement=false | mandatory | | | [1..x]=>mandatory | default=false | | | substatement=true | | | | | | +-------------------------------------------------------------------+ | 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 | "config" | | | | substatement (false) | | +-------------------------------------------------------------------+ | valueRange | "range" or "length" | | | | substatement of "type"| | | | substatement | | +-------------------------------------------------------------------+ | passedById | ?? | | +-------------------------------------------------------------------+ | support | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | condition | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | error notfication? | "must" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current" | | | substatement | "deprecated" | | | | "obsolete" | | | | default="current"| +-------------------------------------------------------------------+ | unit? | "units" substatement | | +-------------------------------------------------------------------+ | {} | "when" substatement | | +-------------------------------------------------------------------+ ]]>

Note: YANG allows also in-line enumerations which are not possible in UML

new built-in type? | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | ?? | | +-------------------------------------------------------------------+ ]]>

"enum" statement | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | literal name | "value" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current", | | | substatement | "deprecated", | | | | "obsolete" | | | | default=current | +-------------------------------------------------------------------+ | ?? | "if-feature" statement| | +-------------------------------------------------------------------+ ]]>

"typeDef" statement | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | type | "type" substatement | | | | (built-in type) | | +-------------------------------------------------------------------+ | 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. | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current", | | | substatement | "deprecated", | | | | "obsolete" | | | | default=current | +-------------------------------------------------------------------+ | unit? | "units" statement | | +-------------------------------------------------------------------+ ]]>

"grouping" statement | +-------------------------------------------------------------------+ | UML Artifact | YANG Artifact | Comment | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | not used | "action" substatement | | +-------------------------------------------------------------------+ | XOR | "choice" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current", | | | substatement | "deprecated", | | | | "obsolete" | | | | default=current | +-------------------------------------------------------------------+ | complex attribute | "uses" statement | | +-------------------------------------------------------------------+ ]]>

Container? | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | abstract | ?? | | +-------------------------------------------------------------------+ | support | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | condition | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ ]]>

"action" and "rpc" statements | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | pre-condition | ?? | | +-------------------------------------------------------------------+ | post-condition | ?? | | +-------------------------------------------------------------------+ | input parameter | "input" substatement | | +-------------------------------------------------------------------+ | output parameter | "output" substatement | | +-------------------------------------------------------------------+ | operation exceptions | ?? | | +-------------------------------------------------------------------+ | isOperationIdempotent | ?? | | +-------------------------------------------------------------------+ | isAtomic | ?? | | +-------------------------------------------------------------------+ | support | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | condition | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current", | | | substatement | "deprecated", | | | | "obsolete" | | | | default=current | +-------------------------------------------------------------------+ ]]>

Note: 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 not.

"notification" statement | +-------------------------------------------------------------------+ | documentation | "description" | | | | substatement | | +-------------------------------------------------------------------+ | support | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | condition | "if-feature" | | | | substatement | | +-------------------------------------------------------------------+ | XOR | "choice" | | | | substatement | | +-------------------------------------------------------------------+ | error notification? | "must" | | | | substatement | | +-------------------------------------------------------------------+ | hyperlink? | "reference" | Papyrus doesn't | | | substatement | support hyperlinks| +-------------------------------------------------------------------+ | lifecycle stereotypes | "status" | "current", | | | substatement | "deprecated", | | | | "obsolete" | | | | default=current | +-------------------------------------------------------------------+ | complex attribute | "uses" | | | | substatement | | +-------------------------------------------------------------------+ ]]>

When translating from UML information models to YANG data models some mapping rules are straightforward, and some are not. This section provides considerations and recommendations for the more complex translations.

Statically define a number of recursion levels Reference Based Approach In the static approach, some number of recursion levels is pre-configured. In the Reference-based approach, a flat list is maintained using hierarchical identities. The reference-based approach is generally preferred because there is no arbitrary limitation set in the solution.

TBD

May use the "presence" property of the container statement?

Use the "choice" property of the container statement.

This memo includes no request to IANA.

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.

&RFC2119; &RFC6020; &I-D.draft-ietf-netmod-rfc6020bis; &I-D.dharini-netmod-g-698-2-yang; &I-D.lam-teas-usage-info-model-net-topology; OMG OMG

The YANG data schema (in tree format) shown below was extracted from dharini-netmod-g-698-2-yang and represents the same data as UML model appearing in after the tree format. Note: The color code used in the tree format corresponds to the color code used in the UML class diagram.