Runs request in the background The client should register callback selector in order to get notified about various events (failure, completion, etc.) Usage id<SDMRequesting> m_Request = [SDMRequestBuilder requestWithURL:url]; [m_Request setDelegate:self]; [m_Request setDidFinishSelector:(serviceDocFetchComplete:)]; [m_Request setDidFailSelector:(serviceDocFetchFailed:)]; [m_Request startAsynchronous];