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Silverlight async request with F#
f#silverlightxamlasync

I'm using Microsoft (R) F# 2.0 Interactive build 4.0.40219.1 (in my logics dll and Silverlight 5.0 Beta xaml c#-project as client).

I'm just trying to make a web-request from Silverlight for non-SSL-site and I have added clientaccesspolicy.xml -file.
Async seems not to work and I have no options. 

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//Both IE8 and Firefox will be not responding:
let internal fetch1 (url : Uri) = 
    let req:HttpWebRequest = downcast WebRequest.Create (url)
    let asynccall =
        async{
            let! res = req.AsyncGetResponse() 
            use stream = res.GetResponseStream()
            use reader = new StreamReader(stream)
            return reader.ReadToEnd()
        }
    asynccall |> Async.RunSynchronously // TILT
 
//Same here:
let internal fetch2 (url : Uri) = 
    let req:HttpWebRequest = downcast WebRequest.Create (url)
    let res = req.AsyncGetResponse() 
              |> Async.RunSynchronously //TILT
    use stream = res.GetResponseStream()
    use reader = new StreamReader(stream)
    let ret = reader.ReadToEnd()
    res.Close |> ignore
    ret
 
//this won't help:
let internal fetch3 (url : Uri) = 
    let result = new System.Windows.Controls.TextBlock()
    let req:HttpWebRequest = downcast WebRequest.Create (url)
    let asynccall =
        async{
            let! res = req.AsyncGetResponse() 
            use stream = res.GetResponseStream()
            use reader = new StreamReader(stream)
            result.Text <- reader.ReadToEnd()
        }
    asynccall |> Async.StartImmediate      
    result.Text // Empty!
 
//Will give browser to crash: Unhandled Error in Silverlight Application 4004
let internal fetch4 (url : Uri) = 
    let req:HttpWebRequest = downcast WebRequest.Create (url)
    let callback a = ()
    let ar= req.BeginGetResponse(new AsyncCallback(callback),req)
    //ar.AsyncWaitHandle.WaitOne(500) |> ignore //TILT: System.NotSupportedException
    //Async.AwaitIAsyncResult(ar) |> ignore //no help
    let res = req.EndGetResponse(ar);
    use stream = res.GetResponseStream() //TILT: System.NullReferenceException
    use reader = new StreamReader(stream)
    reader.ReadToEnd()
 
let internal fetch5 (url : Uri) = 
    let result = ref ""
    let areq:HttpWebRequest = downcast WebRequest.Create (url)
    let callback (ar:IAsyncResult) =
        let req = ar.AsyncState :?> HttpWebRequest
        let res = req.EndGetResponse(ar)  //TILT: ManagedRuntimeError: System.Security.SecurityException
        use stream = res.GetResponseStream()
        use reader = new StreamReader(stream)
        let update x = result := reader.ReadToEnd()
        (new Windows.Controls.TextBox()).Dispatcher.BeginInvoke(new System.Action(update)) |> ignore        
    areq.BeginGetResponse(new AsyncCallback(callback),areq) |> ignore
    !result //Wouldn't update enough fast... but I could wait...
 
//Still won't work:
let internal fetch6 (url : Uri) = 
    let result = new System.Windows.Controls.TextBlock()
    let areq:HttpWebRequest = downcast WebRequest.Create (url)
    let callback (ar:IAsyncResult) =
        let req = ar.AsyncState :?> HttpWebRequest
        let res = req.EndGetResponse(ar)  // TILT: ManagedRuntimeError: System.Security.SecurityException
        use stream = res.GetResponseStream()
        use reader = new StreamReader(stream)
        let update x = result.Text <- reader.ReadToEnd()
        result.Dispatcher.BeginInvoke(new System.Action(update)) |> ignore        
    let ares = areq.BeginGetResponse(new AsyncCallback(callback),areq)
    Async.AwaitIAsyncResult(ares) |> ignore
    result.Text //Empty!

Any ideas?

.

I added added domains to trusted sites...
Well the real problem with this ManagedRuntimeError: System.Security.SecurityException seems to be that the server doesn't have right crossdomain.xml. I should do my own service to wrap the service.

I changed my call to point to localhost and got this working.
The latest code (with installed F# Power Pack to get AsyncReadToEnd) is this:

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let mutable callresult = ""
//let event = new Event<string>()
//let eventvalue = event.Publish
 
let internal fetch (url : Uri) = 
    let req = WebRequest.CreateHttp url
    req.CookieContainer <- new CookieContainer()
    let asynccall =
        async{
            try
                let! res = req.AsyncGetResponse() 
                use stream = res.GetResponseStream()
                use reader = new StreamReader(stream)
                let! txt = reader.AsyncReadToEnd()
                //event.Trigger(txt)
                callresult <- txt
            with
                | :? System.Exception as ex -> //for debug
                    failwith(ex.ToString()) 
        }

    asynccall |> Async.StartImmediate
By on 6/1/2011 6:55 AM ()

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