Configuring the Data Service (WCF Data Services)

With WCF Data Services, you can create data services that expose Open Data Protocol (OData) feeds. Data in these feeds can come from a variety of data sources. WCF Data Services uses data providers to expose this data as an OData feed. These providers include an Entity Framework provider, a reflection provider, and a set of custom data service provider interfaces. The provider implementation defines the data model for the service. For more information, see Data Services Providers.

In WCF Data Services, a data service is a class that inherits from the DataService<T> class, where the type of the data service is the entity container of the data model. This entity container has one or more properties that return an IQueryable<T>, which are used to access entity sets in the data model.

The behaviors of the data service are defined by the members of the DataServiceConfiguration class, and by members of the DataServiceBehavior class, which is accessed from the DataServiceBehavior property of the DataServiceConfiguration class. The DataServiceConfiguration class is supplied to the InitializeService method that is implemented by the data service, as in the following implementation of a Northwind data service:

// This method is called only once to initialize service-wide policies.
public static void InitializeService(DataServiceConfiguration config)
{
    // Set the access rules of feeds exposed by the data service, which is
    // based on the requirements of client applications.
    config.SetEntitySetAccessRule("Customers", EntitySetRights.AllRead);
    config.SetEntitySetAccessRule("Employees", EntitySetRights.ReadSingle);
    config.SetEntitySetAccessRule("Orders", EntitySetRights.All
        | EntitySetRights.WriteAppend
        | EntitySetRights.WriteMerge);
    config.SetEntitySetAccessRule("Order_Details", EntitySetRights.All);
    config.SetEntitySetAccessRule("Products", EntitySetRights.All);

    // Set page size defaults for the data service.
    config.SetEntitySetPageSize("Orders", 20);
    config.SetEntitySetPageSize("Order_Details", 50);
    config.SetEntitySetPageSize("Products", 50);

    // Paging requires v2 of the OData protocol.
    config.DataServiceBehavior.MaxProtocolVersion =
        System.Data.Services.Common.DataServiceProtocolVersion.V2;
}

' This method is called only once to initialize service-wide policies.
Public Shared Sub InitializeService(ByVal config As DataServiceConfiguration)
    ' Set the access rules of feeds exposed by the data service, which is
    ' based on the requirements of client applications.
    config.SetEntitySetAccessRule("Customers", EntitySetRights.AllRead)
    config.SetEntitySetAccessRule("Employees", EntitySetRights.ReadSingle)
    config.SetEntitySetAccessRule("Orders", EntitySetRights.AllRead _
        Or EntitySetRights.WriteAppend _
        Or EntitySetRights.WriteMerge)
    config.SetEntitySetAccessRule("Order_Details", EntitySetRights.All)
    config.SetEntitySetAccessRule("Products", EntitySetRights.ReadMultiple)

    ' Set page size defaults for the data service.
    config.SetEntitySetPageSize("Orders", 20)
    config.SetEntitySetPageSize("Order_Details", 50)
    config.SetEntitySetPageSize("Products", 50)

    ' Paging requires v2 of the OData protocol.
    config.DataServiceBehavior.MaxProtocolVersion = _
        System.Data.Services.Common.DataServiceProtocolVersion.V2
End Sub

Data Service Configuration Settings

The DataServiceConfiguration class enables you to specify the following data service behaviors:

Minimum Resource Access Requirements

The following table details the minimum entity set rights that must be granted to execute a specific operation. Path examples are based on the Northwind data service that is created when you complete the quickstart. Because both the EntitySetRights enumeration and the ServiceOperationRights enumeration are defined by using the FlagsAttribute, you can use a logical OR operator to specify multiple permissions for a single entity set or operation. For more information, see How to: Enable Access to the Data Service.

¹ In this example, Address represents a complex type property of the Customers entity that has a property named StreetAddress. The model used by the Northwind data services does not explicitly define this complex type. When the data model is defined by using the Entity Framework provider, you can use the Entity Data Model tools to define such a complex type. For more information, see How to: Create and Modify Complex Types.

² This URI is supported when a property that returns a binary large object (BLOB) is defined as the media resource that belongs to an entity that is a media link entry, which in this case, is Customers. For more information, see Streaming Provider.

Versioning Requirements

The following data service configuration behaviors require version 2 of the OData protocol, or later versions:

• Support for count requests.

• Support for the $select query option for projection.

For more information, see Data Service Versioning.

See also

• Defining WCF Data Services
• Hosting the Data Service