Question

I have two identical web services currently installed on the same PC for testing purposes. A request that is received by the first service, is suposed go to the second one as well. My intention was to do this using a HttpModule. I handle the request during application.BeginRequest.

public void AsyncForwardRequest(HttpRequest request)
{
    try
    {
        // Prepare web request...
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(WSaddress);

        req.Credentials = CredentialCache.DefaultCredentials;
        req.Headers.Add("SOAPAction", request.Headers["SOAPAction"]);
        req.ContentType = request.Headers["Content-Type"];
        req.Accept = request.Headers["Accept"];
        req.Method = request.HttpMethod;

        // Send the data.
        long posStream = request.InputStream.Position;
        long len = request.InputStream.Length;
        byte[] buff = new byte[len];
        request.InputStream.Seek(0, SeekOrigin.Begin);
        if (len < int.MaxValue && request.InputStream.Read(buff, 0, (int)len) > 0)
        {
            using (Stream stm = req.GetRequestStream())
            {
                stm.Write(buff, 0, (int)len);
            }

            request.InputStream.Position = posStream;
            DebugOutputStream(request.InputStream);
            request.InputStream.Seek(0, SeekOrigin.Begin);

            IAsyncResult result = (IAsyncResult)req.BeginGetResponse(new AsyncCallback(RespCallback), req);
        }
    }
    catch (Exception ex)
    {

        App.Error2(String.Format("RequestDuplicatorModule - BeginRequest; ERROR begin request: {0}", ex.Message), ex);
    }

private static void RespCallback(IAsyncResult asynchronousResult)
{
    try
    {
        // State of request is asynchronous.
        var req = (HttpWebRequest)asynchronousResult.AsyncState;
        WebResponse resp = (HttpWebResponse)req.EndGetResponse(asynchronousResult);

        Stream responseStream = resp.GetResponseStream();
        System.IO.Stream stream = responseStream;
        Byte[] arr = new Byte[1024 * 100];
        stream.Read(arr, 0, 1024 * 100);
        if (arr.Length > 0)
        {
            string body = (new ASCIIEncoding()).GetString(arr);
            Debug.Print(body);
        }
    }
    catch (WebException ex)
    {
        App.Error2(String.Format("RequestDuplicatorModule - BeginRequest; ERROR begin request: {0}", ex.Message), ex);
    }

}

This (HttpWebResponse)req.EndGetResponse(asynchronousResult) throws an exception: 500 Internal Server Error and fails. The original request goes through fine.

request.InnerStream:
…

Does this have anything to do with the web service addresses being different? In my case they’re:
http://localhost/WS/service.asmx
http://localhost/WS_replicate/service.asmx

Answer 1

Was able to modify the AsyncForwardRequest method so that I can actually edit the SoapEnvelope itself:

string buffString = System.Text.UTF8Encoding.UTF8.GetString(buff);

using (Stream stm = req.GetRequestStream())
{
    bool stmIsReadable = stm.CanRead;  //false, stream is not readable, how to get
                                       //around this?
                                       //solution: read Byte Array into a String,
                                       //modify <wsa:to>, write String back into a
                                       //Buffer, write Buffer to Stream

    buffString = buffString.Replace("http://localhost/WS/Service.asmx", WSaddress);

    //write modded string to buff
    buff = System.Text.UTF8Encoding.UTF8.GetBytes(buffString);

    stm.Write(buff, 0, (int)buff.Length);
}