Capturing SOAP requests to an ASP.NET ASMX web service

asmxasp.netsoapweb services

Consider the requirement to log incoming SOAP requests to an ASP.NET ASMX web service. The task is to capture the raw XML being sent to the web service.

The incoming message needs to be logged for debug inspection. The application already has its own logging library in use, so the ideal usage would be something like this:

//string or XML, it doesn't matter.
string incomingSoapRequest = GetSoapRequest();

Logger.LogMessage(incomingSoapRequest);
  • Are there any easy solutions to capture the raw XML of the incoming SOAP requests?
  • Which events would you handle to get access to this object and the relevant properties?
  • Is there anyway IIS can capture the incoming request and push to a log?

Best Answer

You can also implement by placing the code in Global.asax.cs

protected void Application_BeginRequest(object sender, EventArgs e)
{
    // Create byte array to hold request bytes
    byte[] inputStream = new byte[HttpContext.Current.Request.ContentLength];

    // Read entire request inputstream
    HttpContext.Current.Request.InputStream.Read(inputStream, 0, inputStream.Length);

    //Set stream back to beginning
    HttpContext.Current.Request.InputStream.Position = 0;

    //Get  XML request
    string requestString = ASCIIEncoding.ASCII.GetString(inputStream);

}

I have a Utility method in my web service that I use to capture the request when something happens that I am not expecting like a unhandled exception.

    /// <summary>
    /// Captures raw XML request and writes to FailedSubmission folder.
    /// </summary>
    internal static void CaptureRequest()
    {
        const string procName = "CaptureRequest";

        try
        {
            log.WarnFormat("{0} - Writing XML request to FailedSubmission folder", procName);

            byte[] inputStream = new byte[HttpContext.Current.Request.ContentLength];

            //Get current stream position so we can set it back to that after logging
            Int64 currentStreamPosition = HttpContext.Current.Request.InputStream.Position;

            HttpContext.Current.Request.InputStream.Position = 0;

            HttpContext.Current.Request.InputStream.Read(inputStream, 0, HttpContext.Current.Request.ContentLength);

            //Set back stream position to original position
            HttpContext.Current.Request.InputStream.Position = currentStreamPosition;

            string xml = ASCIIEncoding.ASCII.GetString(inputStream);

            string fileName = Guid.NewGuid().ToString() + ".xml";

            log.WarnFormat("{0} - Request being written to filename: {1}", procName, fileName);

            File.WriteAllText(Configuration.FailedSubmissionsFolder + fileName, xml);
        }
        catch
        {
        }

    }

Then in web.config I store several AppSetting values that define what level I want to use to capture the request.

    <!-- true/false - If true will write to an XML file the raw request when any Unhandled exception occurrs -->
    <add key="CaptureRequestOnUnhandledException" value="true"/>

    <!-- true/false - If true will write to an XML file the raw request when any type of error is returned to the client-->
    <add key="CaptureRequestOnAllFailures" value="false"/>

    <!-- true/false - If true will write to an XML file the raw request for every request to the web service -->
    <add key="CaptureAllRequests" value="false"/>

Then in my Application_BeginRequest I have it modified like so. Note that Configuration is a static class I create to read properties from web.config and other areas. 

    protected void Application_BeginRequest(object sender, EventArgs e)
    {

        if(Configuration.CaptureAllRequests)
        {
            Utility.CaptureRequest();
        }
    }
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