Call Page WebMethod from a Winforms Client using AJAX

My primary idea for this post was how to use the small and beauty JSON format for data transfer in a windows mobile application. For that I use the infrastructure of AJAX. I implement a Webmethod in a classic ASPX page.

<script runat="server">

</script>

For calling the Method form the page (or from a webservice) i use a Winforms application and the httpwebrequest class. Then i call the URL following the method name. The second part is to use a specific content  type in header "application/json". To transfer complex data you have to build a json type. For my sample i used a simple string containing "test". The contextKey is a reserved word.

The result is in my sample also a string and can be passed to a textbox.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim wRequest As HttpWebRequest = HttpWebRequest.Create("http://url/Default4.aspx/Nachladen1")

wRequest.Method = "POST"

wRequest.ContentType = "application/json; charset=utf-8"

wRequest.Headers.Add(HttpRequestHeader.Pragma.ToString, "no-cache")

Using writer As Stream = wRequest.GetRequestStream

Dim send As String

send = "{""contextKey"":""test""}"

Dim data As [Byte]() = Encoding.ASCII.GetBytes(send)

End Using

Dim WResponse As HttpWebResponse = CType(wRequest.GetResponse, HttpWebResponse)

Dim recieve As StreamReader = New StreamReader(WResponse.GetResponseStream())

Dim result As String = recieve.ReadToEnd.ToString

End Sub

Small nice and sexy!

AJAX