[OASIS Issue Tracker] Created: (ODATA-278) Introduce edm:Url expression as child element of the edm:Annotation element.

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

Introduce edm:Url expression as child element of the edm:Annotation element.
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                 Key: ODATA-278
                 URL: http://tools.oasis-open.org/issues/browse/ODATA-278
             Project: OASIS Open Data Protocol (OData) TC
          Issue Type: Improvement
          Components: OData CSDL
    Affects Versions: V4.0_WD01
         Environment: [Proposed] 
            Reporter: Martin Zurmuehl
             Fix For: V4.0_WD01


In mashup scenarios it is often the case that a third party can detect a rule that allows constructing URLs from information provided in an entity that allow navigation to other resources in the web. 
Annotations allow to express these construction rules, this construction rules can also be seen as "special navigation properties defined via annotations".

We want to annotate these "special navigagtion properties" in a such a way, that they can be used in further annotation similar to native navigation properties.
In the following example two navigation properties ( to a supplier and to purchase orders ) and one property is annotated at the product entity type; and they are used in a other annotation. This example is currently invalid, because  the <Url> element isn't specified so far.
Complete annotation file example (it uses https://tools.oasis-open.org/issues/browse/ODATA-257):

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="4.0" xmlns:edmx="http://docs.oasis-open.org/odata/ns/edmx/4.0";>
  <edmx:Reference Url="http://biz.org/odata/foobar/ProductService.srv/$metadata"; />
  <edmx:Reference Url="http://example.org:1234/odata/bar/SupplierService.srv/$metadata"; />
  <edmx:Reference Url="http://somewhere.org/odata/foo/Purchasing.srv/$metadata"; />
  <edmx:DataServices DataServiceVersion="4.0">
    <Schema xmlns="http://docs.oasis-open.org/odata/ns/csdl/4.0"; Namespace="AnnotationCrossReference" Alias="ACR">
      <Using Namespace="com.sap.erp.products" Alias="ServiceA" />
      <Using Namespace="com.sap.erp.supplier" Alias="ServiceB" />
      <Using Namespace="com.sap.foo.purchasing" Alias="ServiceC" />

      <Term Name="DataFieldWithNavigation" Type="DataFieldWithNavigationType" />
      <ComplexType Name="DataFieldWithNavigationType">
        <Property Name="Label" Type="String" Nullable="true">
          <Annotation Term="Core.IsLanguageDependent" />
        </Property>
        <Property Name="Value" Type="Edm.PrimitiveType" Nullable="false" />
        <Property Name="NavigationPath" Type="Edm.NavigationPropertyPath" Nullable="false" />
      </ComplexType>


      <Term Name="Supplier" Type="ServiceB.Supplier" />
      <Term Name="PurchaseOrders" Type="Collection(ServiceC.PurchaseOrder)" />
      <Term Name="NumberOfPurchaseOrders" Type="Edm.Int32" />


      <Annotations Target="ServiceA.Product">
        <Annotation Term="Supplier">
          <Url>
            <Apply Function="odata.fillUriTemplate">
              <!-- ... construct path to ServiceB.Supplier -->
              <String>http://example.org:1234/odata/bar/SupplierService.srv/Suppliers('{suppID}')</String>
              <LabeledElement Name="suppID">
                <Apply Function="odata.UriEncode">
                  <Path>SupplierId</Path>
                </Apply>
              </LabeledElement>
            </Apply>
          </Url>
        </Annotation>
        <Annotation Term="PurchaseOrders">
          <Url>
            <Apply Function="odata.fillUriTemplate">
              <!-- ... construct path to a ServiceC.EntiySet of entity type PurchaseOrders -->
              <String>http://somewhere.org/odata/foo/Purchasing.srv/PurchaseOrders?$search={productID}</String>
              <LabeledElement Name="productID">
                <Apply Function="odata.UriEncode">
                  <Path>ProductKey</Path>
                </Apply>
              </LabeledElement>
            </Apply>
          </Url>
        </Annotation>
        <Annotation Term="NumberOfPurchaseOrders">
          <Url>
            <Apply Function="odata.fillUriTemplate">
              <!-- ... construct path an int value -->
              <String>http://somewhere.org/odata/foo/Purchasing.srv/PurchaseOrders/$count?$search={productID}</String>
              <LabeledElement Name="productID">
                <Apply Function="odata.UriEncode">
                  <Path>ProductKey</Path>
                </Apply>
              </LabeledElement>
            </Apply>
          </Url>
        </Annotation>


        <Annotation Term="DataFieldWithNavigation" Qualifier="FirstDataField">
          <Record>
            <PropertyValue Property="Label" String="Supplier" />
            <PropertyValue Property="Value" Path="@ACR.Supplier/SupplierName" />
            <PropertyValue Property="NavigationPath" NavigationPropertyPath="@ACR.Supplier" />
          </Record>
        </Annotation>

        <Annotation Term="DataFieldWithNavigation" Qualifier="SecondDataField">
          <Record>
            <PropertyValue Property="Label" String="Purchase Orders" />
            <PropertyValue Property="Value" Path="@ACR.NumberOfPurchaseOrders" />
            <PropertyValue Property="NavigationPath" NavigationPropertyPath="@ACR.PurchaseOrders" />
          </Record>
        </Annotation>
      </Annotations>


    </Schema>
  </edmx:DataServices>
</edmx:Edmx>

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