...
YANG Language
- The YANG language provides us the ability to define and model configurations and state data by defining YANG modules
- Modules contain a sequence of statements
- Statement syntax is either of the following :
- statement = keyword [argument] ;
- statement = keyword [argument] { <substatement(s)..> } ;
...
Sample YANG (stores.yang with extension) | Statements and Description |
|---|
| Code Block |
|---|
| language | yml |
|---|
| title | stores model with extension |
|---|
| linenumbers | true |
|---|
| module sync-enxtensionextension {
…
prefix sync-exext;
…
extension sync-flag{
description
“This is a sample extension statement description“
argument "value";
}
….
}
|
| Code Block |
|---|
| language | yml |
|---|
| title | extended-stores model |
|---|
| linenumbers | true |
|---|
| module extended-stores {
yang-version 1.1;
...
import sync-extension{
prefix sync-exext;
}
typedef year {
type uint16 {
range "1000..9999";
}
}
container bookstore {
sync-exext:sync-flag "on";
...
}
}
|
| extension Statement see example from Lines 5-9 on stores model with extension | Code Block |
|---|
| extension <keyword/identifier>{
<extension substatements...>
} |
see example from Line 15 on extended-stores model | Code Block |
|---|
| <module prefix>:<extension keyword> "argument"; |
- to be used to define new statements
- available to be imported and used by other modules just like a normal YANG statement
- by use of 'import statement' to import the module where the extension is defined
- statements that do not have any substatements can have extensions defined if wanted
- its only one argument is the identifier and keyword for the extension
- Optional substatements:
- argument Statement
- description Statement
- reference Statement
- defined extension Statements
argument Statement see examples from Line 6 on stores model - takes a string argument which is the name of the argument to the keyword
- Optional substatement
|
| Code Block |
|---|
| language | xml |
|---|
| theme | Midnight |
|---|
| title | YIN-extended-stores model |
|---|
| linenumbers | true |
|---|
| <?xml version="1.0" encoding="UTF-8"?>
<module name="extended-stores"
xmlns="urn:ietf:params:xml:ns:yang:yin:1"
xmlns:ext-book-store="org:onap:ccsdk:sampleExtended"
xmlns:book-store="org:onap:ccsdk:sample">
<namespace uri="org:onap:ccsdk:sampleExtended"/>
<prefix value="ext-book-store"/>
<revision date="2020-09-15">
<description>
<text>Sample Extended Model</text>
</description>
</revision>
<import module="storessync-extension">
<prefix value="booksync-storeext"/>
</import>
<typedef name="year">
<type name="uint16">
<range value="1000..9999"/>
</type>
</typedef>
<container name="bookstore">
<book<sync-storeext:sync-flag value="on"/>
<leaf name="bookstore-name">
<type name="string"/>
</leaf>
...
</container>
</module> |
| yin-element Statement - takes a string argument which is true or false
- yin-element is 'false' by default
- if the argument is 'true' it indicates that the argument is mapped to an XML element in YIN or to an XML attribute
Notes - Line 22 on YIN-extended-stores model
- result of using the argument without specifying the yin-element value
- yin-element is 'false'
- the argument 'value' is only an XML attribute
- if argument statement (Line 6 on stores model) contains yin-element substatement YIN-extend-stores model would result to the following:
extension statement will produce a child node | Code Block |
|---|
| theme | Midnight |
|---|
| title | YIN-extended-stores model where yin-element is 'true' |
|---|
| ...
<container name="bookstore">
<book<sync-storeext:sync-flag>
<book<sync-storeext:value>on</booksync-storeext:value>
</booksync-storeext:sync-flag>
...
</container>
... |
** this does not extend the data
|
** the YIN the YIN version and Schema trees above are generated by YANG validator 'pyang'
...
**Red cell for case number indicates that tests have failed
- the extension is defined as substatement in the module with argument statement as its substatement
...
| Case # | Description | Result |
|---|
| 1 | - Created schema set
- the model contained only an extension definition
| - successfully stored yang resource
- successfully created a node using the model
- fragment table did not add the extension argument in attributes
|
| 2 | - Created schema set
- the model contained an extension definition and the model was used inside a container node
| - successfully stored yang resource
- successfully created a node using the model
- fragment table did not add the extension argument in attributes
*the same result acquired for all passed cases on the groovy tests table above |
| 3 | - Created schema set
- the model contained only an extension definition
- extension contains argument
| - creating the schema set failed
- received 500 server error parsing schema set
|
| 4 | - Created schema set
- the model contained an extension definition and was used inside the container node
- extension contains argument
| - creating the schema set failed
- received 500 server error parsing schema set
|
Conclusions
- The YANG language extension analysis above is only applicable for type information.
- Extension does not extend the actual data of the model instance
- Based on the test scenarios above, extensions can only be seen on the schema sets and not on the data
- Further investigation is required to cover interpretation as the analysis above only covers parsing
- see
| Jira |
|---|
| server | ONAP Jira |
|---|
| serverId | 425b2b0a-557c-3c0c-b515-579789cceedb |
|---|
| key | CPS-866 |
|---|
|
