[OASIS Issue Tracker] (ODATA-1064) Add ability to annotate collections to return only count and NextLink

[OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org>]

     [ https://issues.oasis-open.org/browse/ODATA-1064?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

George Ericson updated ODATA-1064:
----------------------------------

    Proposal: 
----------------
Add new IncludeCount term:
----------------
<Term Name="IncludeCount" AppliesTo="Collection" Type="Edm.Binary">
    <Annotation Term="Core.Description" 
          String="If true, the @odata.count annotation shall be returned for each collection in a response." />
</Term>
=========
Add new option to Accept header for application/json with metadata=minimal
--------------------
To odata-json-format, add clause 3.1.x

3.1.x metadata=minimal+navigationLink (odata.metadata=minimal+navigationLink)
The metadata=minimal+navigationLink format parameter indicates that the service MUST respond as specified for metadata=minimal with the exception that for each EntitySet or collection NavigationProperty, the initial response payload MUST include 
•	navigationLink: The navigation link to the collection.

--------------------
Example:

------------------
Proposed schema
<EntityType Name="Top">
	…
<NavigationProperty Name="Systems" Type="Collection(ComputerSystem)">
    <Annotation Term="OData.IncludeCount" Bool="true"/>
</NavigationProperty>
…
----------
Example: GET

GET /redfish/v1/Top
Accept: application/json; metadata=minimal+navigationLink

Response
{
"@odata.context": "/redfish/v1/$metadata#Top",
"@odata.id": "/redfish/v1/Top",
"@odata.type": "#Top ",
"Name": "Top",
… 
"Systems@odata.count": 15,
"Systems@odata.navigationLink": {"/redfish/v1/Systems"} 
…
}

  was:
Add new IncludeCount term:
----------------
<Term Name="IncludeMetadata" AppliesTo="NavigationProperty EntitySet Singleton" Type="Core.MetadataKind">
<Annotation Term="Core.Description" 
String="Defines metadata that should automatically be returned in a response when the reply is qualified with 'metadata=minimal'." />
</Term>

<EnumType Name="MetadataKind" IsFlags="true">

  <Member Name="count" Value="1">
    <Annotation Term="Core.Description" 
String="Return count metadata, equivalent to $count." />

  </Member>
  <Member Name="navigationLink" Value="2">
    <Annotation Term="Core.Description" 
String="This URL can be used to retrieve an entity or collection of entities related to the current entity via a navigation property. Doing a GET on this link is equivalent to specifying $expand."/>
  </Member>

  <Member Name="associationLink" Value="4">
    <Annotation Term="Core.Description" 
String=" The value is a URL that can be used to retrieve a reference to an entity or a collection of references to entities related to the current entity via a navigation property. Doing a GET on this link is equivalent to specifying $ref." />
  </Member>

</EnumType>
--------------------
Example:
Proposed schema
<EntityType Name="Top">
	…
<NavigationProperty Name="Systems" Type="Collection(ComputerSystem)">
<Annotation Term="OData.IncludeMetadata" 
EnumMember="Core.MetadataKind/count Core.MetadataKind/navigationLink" />
</NavigationProperty>
…
</EntityType>

<EntityType Name="ComputerSystem">
…
</EntityType>
----------
Example: GET
-----------
GET /redfish/v1/Top
Response
{
"@odata.context": "/redfish/v1/$metadata#Top",
"@odata.id": "/redfish/v1/Top",
"@odata.type": "#Top ",
"Name": "Top",
… 
"Systems@odata.count": 15,
"Systems@odata.navigationlink": {"/redfish/v1/Systems"}
…
}


> Add ability to annotate collections to return only count and NextLink
> ---------------------------------------------------------------------
>
>                 Key: ODATA-1064
>                 URL: https://issues.oasis-open.org/browse/ODATA-1064
>             Project: OASIS Open Data Protocol (OData) TC
>          Issue Type: New Feature
>          Components: Vocabularies
>    Affects Versions: V4.0_CSD01
>            Reporter: George Ericson
>            Assignee: George Ericson
>              Labels: Proposed, request_tc_discussion
>             Fix For: V4.01_CS02, V4.0_ERRATA04
>
>
> Issues with NavigationProperty
> 1)	If AutoExpand or AutoExpandReferences is not specified, then a GET without $expand or $ref query parameters will not return any representation of declared NavigationProperties.
> 2)	If AutoExpand or AutoExpandReferences is specified, the concern is that the returned representation of the containing entity might be too large.
> 3)	For an EntityType containing many NavigationProperties, it is difficult to specify the desired information using query parameters.
> The Redfish specification attempts to solve these issues by introducing an intermediate resource that contains the original collection as a Members collection. The intermediate resource is then referenced via a NavigationProperty with AutoExpandReferences.  The new resource is required to return $count as a metadata property of the Members collection.  The value is the size of the original collection.
> For the most part, this is successful, but the solution creates several new problems.
> 1)	Redfish specifies that a POST to the intermediate resource is equivalent to doing a POST to the contained collection.  This is not conformant.
> 2)	Introduction of many intermediate resources makes the resulting model more complex.



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