IDataServiceStreamProvider::GetStreamETag Method

Returns the eTag of the media resource that belongs to the specified media link entry.

Namespace:  System.Data.Services.Providers
Assembly:  Microsoft.Data.Services (in Microsoft.Data.Services.dll)

String^ GetStreamETag(
	Object^ entity, 
	DataServiceOperationContext^ operationContext


Type: System::Object
The entity that is a media link entry with a related media resource.
Type: System.Data.Services::DataServiceOperationContext
The DataServiceOperationContext instance used by the data service to process the request.

Return Value

Type: System::String
eTag of the media resource associated with the entity.

This method is invoked by the data services framework to obtain the ETag of the stream associated with the entity specified. This metadata is needed when constructing the payload for the Media Link Entry associated with the stream (aka Media Resource) as well as to be used as the value of the ETag HTTP response header. This method enables a stream (Media Resource) to have an ETag which is different from that of its associated Media Link Entry. The returned string MUST be formatted such that it is directly usable as the value of an HTTP ETag response header. If null is returned the data service framework will assume that no ETag is associated with the stream NOTE: Altering properties on the operationContext parameter may corrupt the response from the data service.