Dataservice authentication not working with serviceContext.GetReadStreamUri(..) - wpf

Question

I have an Odata Service and a WPF client application.
Some of the Odata Service Entities have images attached to them (ie.Client).
The streaming works as long as I do not apply authentication. I can view and change the images. Once I enforce authentication everything works as expected, given the credentials check out. All but the images that is. Here are the relevant code steps / snipes.
Window Constructor code
bool iv = System.Web.Security.Membership.ValidateUser("userName", "pass");
ManageService = new InventoryContext(new Uri(...));
ManageService.SendingRequest += new EventHandler<SendingRequestEventArgs (ManageService_SendingRequest);
ManageService_SendingRequest code
//attach the authentication cookie to the request header
((HttpWebRequest)e.Request).CookieContainer = ((ClientFormsIdentity)Thread.CurrentPrincipal.Identity).AuthenticationCookies;
The call to fetch the data is async using background worker
Query Methode()
BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += new DoWorkEventHandler(FetchClient);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(FetchClientsCompleted);
worker.RunWorkerAsync(ClientUUID);
FetchClient
var query = from o in ManageService.Clients where o.ClientUUID.Equals((Guid)e.Argument)
...
e.Result = query;
FetchClientsCompleted
var res = e.Result as DataServiceCollection<Client>;
DataContext = res[0]; //this is all working, with and without authentication
//the next line, binding the stream to the image throws 'unauthenticated'
//it works well if authentication is disabled
imgClient.Source = new BitmapImage(ManageService.GetReadStreamUri(DataContext));
if I debug, the SendingRequest methode, usually called with any query request is NOT triggered calling GetReadStreamUri(...).
This is where I am stuck, what to do to authenticate to the service to get the stream?
Also, I took the URI generated by ManageService.GetReadStreamUri(DataContext), past it into the browser and it works, the image is displayed in the browser, if logged in.
Anyone any ideas?

Answer 1

The SendingRequest handler will only fire for request sent by the DataServiceContext class (your ManageService). But in the case of the picture, you only get the URL from the DataServiceContext and then let the BitmapImage actually issue the HTTP request to that URL. So the event won't fire for that request. I don't know if BitmapImage has a way for you to hook into the HTTP request pipeline (I don't think it does).
You could issue that request yourself and then use the response stream as the input for the bitmap image, in which case you get full control over the request and thus can implement authentication as appropriate.