Adding data to a silverlight HTTP POST Async

I'm trying to send some data using a simple HTTP POST in Silverlight 开发者_开发技巧3.0 but for some reason I can't seem to find a good example on how to do this.

So far this works, but how do I send some data along w/ the request?

Public Sub SubmitMessage()
    request = WebRequestCreator.ClientHttp.Create(New System.Uri("http://localhost:27856/Home.aspx/PostUpdate/"))
    request.Method = "POST"

    Dim result As IAsyncResult = request.BeginGetResponse(New AsyncCallback(AddressOf UpdateDone), Nothing)
End Sub

Public Sub UpdateDone(ByVal ar As IAsyncResult)
    Dim response As HttpWebResponse = request.EndGetResponse(ar)

    Using reader As StreamReader = New StreamReader(response.GetResponseStream())
        Dim valid As String = reader.ReadToEnd()
    End Using
End Sub

You need the BeginGetRequestStream method before getting the response (note VB.NET is not my main language).

Public Sub SubmitMessage()
    request = WebRequestCreator.ClientHttp.Create(New System.Uri("http://localhost:27856/Home.aspx/PostUpdate/"))
    request.Method = "POST"

    request.BeginGetRequestStream(New AsyncCallback(AddressOf SendData), Nothing)
End Sub

Public Sub SendData(ByVal ar As IAsyncResult)
    Dim stream as Stream = state.Request.EndGetRequestStream(ar)
    '' # Pump your data as bytes into the stream.
    stream.Close()
    request.BeingGetResponse(New AsyncCallback(AddressOf UpdateDone), Nothing)
End Sub

Public Sub UpdateDone(ByVal ar As IAsyncResult)
    Dim response As HttpWebResponse = request.EndGetResponse(ar)

    Using reader As StreamReader = New StreamReader(response.GetResponseStream())
        Dim valid As String = reader.ReadToEnd()
    End Using
End Sub

It would seem from your answer that the are posting HTML form data. Here is the correct way to create the entity body (C# sorry):-

    public static string GetUrlEncodedData(Dictionary<string, string> data)
    {
        var sb = new StringBuilder();
        foreach (var kvp in data)
        {
            if (sb.Length > 0) sb.Append("&");
            sb.Append(kvp.Key);
            sb.Append("=");
            sb.Append(Uri.EscapeDataString(kvp.Value));
        }
        return sb.ToString();
    }

Note in particular the use of Uri.EscapeDataString, this the correct way to encode data values for this Content-Type. It assumes that the server is expecting UTF-8 character encoding.

When converting the result of this to a byte array ready for posting you need only use ASCII encoding since the returned string will only ever contain characters within the ASCII range.

The final solution that worked is shown below. Thanks to @AnthonyWJones for his quick answer that got me moving in the right direction!

Public Sub SubmitMessage()
    Dim request As HttpWebRequest = WebRequestCreator.ClientHttp.Create(New System.Uri("http://localhost:27856/Home.aspx/PostUpdate/"))
    request.Method = "POST"
    request.ContentType = "application/x-www-form-urlencoded"

    request.BeginGetRequestStream(New AsyncCallback(AddressOf SendStatusUpdate), request)
End Sub

Public Sub SendStatusUpdate(ByVal ar As IAsyncResult)
    Dim request As HttpWebRequest = DirectCast(ar.AsyncState, HttpWebRequest)

    Dim stream As Stream = request.EndGetRequestStream(ar)

    Dim data As New System.Text.UTF8Encoding
    Dim byteArray As Byte() = data.GetBytes("status=test")

    stream.Write(byteArray, 0, byteArray.Length)
    stream.Close()
    stream.Dispose()

    request.BeginGetResponse(New AsyncCallback(AddressOf StatusUpdateCompleted), request)
End Sub

Public Sub StatusUpdateCompleted(ByVal ar As IAsyncResult)
    Dim request As HttpWebRequest = DirectCast(ar.AsyncState, HttpWebRequest)

    Dim response As HttpWebResponse = request.EndGetResponse(ar)

    Using reader As StreamReader = New StreamReader(response.GetResponseStream())
        Dim valid As String = reader.ReadToEnd()
    End Using
End Sub