How to register own protocol using the WebBrowser control? - silverlight

Question

In a WP7 Silverlight application with a WebBrowser control I want to use an own protocol like "myttp://" to deliver some local content. I can't use Navigate() to an IsolatedStrorage because some content will by created on demand. For the same reason NavigateToString() is also not usable for me.
I tried to register a WebRequestCreator descend for my MYTP protocol
myCreator = new MyRequestCreator();
WebRequest.RegisterPrefix("mytp://", myCreator);
but it isn't called from the browser control if I navigate to "mytp://test.html".
If I create a WebRequest via code
WebRequest request;
request = WebRequest.Create("mytp://test.html");`
everythings works fine.
Any suggestions what is wrong or how to do it?

Answer 1

The WebBrowser control will use the Windows Phone Internet Explorer Browser's HTTP stack to statisfy web requests. This HTTP stack is entirely separate from the Client HTTP stack being used by the application. Hence the browser does not see your protocol at all.

Answer 2

I agree with AnthonyWJones words, though I dont know, what exactly he meant by "Browser HTTP stack".
The standard Silverlight's "access to Browser's stack" (used to handle sessions etc) in form of System.Net.Browser.WebRequestCreator.BrowserHttp httprequest factory (versus the "normal/aside" System.Net.Browser.WebRequestCreator.ClientHttp factory) is actually available to the application code in WP7. It is hidden from the SDK, but available on the device and with small effort, the application can use it, for example, to have its emitted cookies in sync with the Browser's cache. For description, please see my humble other post
However, while using that factory and having all your session/cookies/userauth handling within those connections in sync with the WebBrowser, despite being very similar to the ClientHttp factory, you find (at least in 7.0 and 7.1 versions) that it is completely ignorant of any custom prefixes. Trying to open anything with this factory results in (WP7 v. Mango 7.1):
A first chance exception of type 'System.Net.ProtocolViolationException' occurred in System.Windows.dll
at System.Net.Browser.BrowserHttpWebRequest.InternalBeginGetRequestStream(AsyncCallback callback, Object state)
at System.Net.Browser.AsyncHelper.BeginOnUI(BeginMethod beginMethod, AsyncCallback callback, Object state)
at System.Net.Browser.BrowserHttpWebRequest.BeginGetRequestStream(AsyncCallback callback, Object state)
at MyApp.MyPage..ctor()
relevant code snippet of the MyPage:
public class WRC : IWebRequestCreate { public WebRequest Create(Uri uri) { return null;/*BREAKPOINT1*/ } }
WebRequest.RegisterPrefix("js://", new WRC()); // register the above handler
brwHttp = (IWebRequestCreate)typeof(System.Net.Browser.WebRequestCreator).GetProperty("BrowserHttp").GetValue(null, null);
var tmp = brwHttp.Create(new Uri("js://blah.blah.blah"));
var yyy = tmp.BeginGetResponse(callback, "wtf");
var response = tmp.EndGetResponse(yyy); /*BREAKPOINT2*/
var zzz = tmp.BeginGetRequestStream(callback, "wtf"); /*<---EXCEPTION*/
var stream = tmp.EndGetRequestStream(zzz); /*BREAKPOINT3*/
Execution results:
breakpoint1 never hit
breakpoint2 allows to see that "response" is NULL
breakpoint3 never hit due to the exception pasted above
My conclusion is, that the Silverlight Browser's stack is hardcoded to use some builtin set of prefixes, and all other prefixes are ignored/throw ProtocolViolation. My guess is, that in WP7 (7.0, 7.1) they are actually hardcoded to use http since my custom "js://" was passed to a BrowserHttpWebRequest.InternalBeginGetRequestStream as it's visible on the stacktrace :)
That confirms what Anthony had written - no way of having custom protocol handlers to work gracefully with the Silverlight's Browser Stack API.
However, I cannot agree with that the WebBrowser uses this connection factory. While is it true that the hidden factory is called BrowserHttp, and is true that it shares some per-user or per-session settings with the webbrowser, everything I try tens to indicate that the WebBrowser component uses yet completly other factory for its connections, and quite probably it is some native one. As an argument for that, I can only provide that I was able to successfully replace the original BrowserHttp factory with my simple custom implementation of it (both on the emulator and the phone), and with at least 6 webbrowsers in my current app, it wasn't used at all, not even once! (neither on the emulator, nor phone)