WCF + REST: Where is the request data?

Question

I'm currently developing a WCF RESTful service. Within the validation of the POST data, I am throwing exceptions if the request XML does not conform to our business rules.

The goal is to send an e-mail to the appropriate staff if a request comes in that considered invalid. But, along with the incoming request headers, method and URI, I'd like to also send the XML that was posted.

I have not been able to find a way to access this data. Is WCF actually destroying the request body/data before I have a chance to access it or am I missing something?

Your help is appreciated as I'm confused as to why I can't access the request data.

Answer 1

In the answer to this question I provide a horrible solution to the problem. I'm still waiting for someone to suggest a better way.

Answer 2

This unfortunately isn't supported- we had a similar need, and did it by calling internal members with reflection. We just use it in an error handler (so we can dump the raw request), but it works OK. I wouldn't recommend it for a system you don't own and operate though (eg, don't ship this code to a customer), since it can change at any time with a service pack or whatever.

    public static string GetRequestBody()
    {
        OperationContext oc = OperationContext.Current;

        if (oc == null)
            throw new Exception("No ambient OperationContext.");

        MessageEncoder encoder = oc.IncomingMessageProperties.Encoder;
        string contentType = encoder.ContentType;
        Match match = re.Match(contentType);

        if (!match.Success)
            throw new Exception("Failed to extract character set from request content type: " + contentType);

        string characterSet = match.Groups[1].Value;

        object bufferedMessage = operationContextType.InvokeMember("request",
            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.GetField,
            null, oc, null);

        //TypeUtility.AssertType(bufferedMessageType, bufferedMessage);

        object messageData = bufferedMessageType.InvokeMember("MessageData",
            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.GetProperty,
            null, bufferedMessage, null);

        //TypeUtility.AssertType(jsonBufferedMessageDataType, messageData);

        object buffer = jsonBufferedMessageDataType.InvokeMember("Buffer",
            BindingFlags.Instance | BindingFlags.Public | BindingFlags.GetProperty,
            null, messageData, null);

        ArraySegment<byte> arrayBuffer = (ArraySegment<byte>)buffer;

        Encoding encoding = Encoding.GetEncoding(characterSet);

        string requestMessage = encoding.GetString(arrayBuffer.Array, arrayBuffer.Offset, arrayBuffer.Count);

        return requestMessage;
    }

Answer 3

So, if you declare your contract something like:

[WebInvoke(Method = "POST", UriTemplate = "create", ResponseFormat=WebMessageFormat.Json)]
 int CreateItem(Stream streamOfData);

(you can use XML instead) The streamOfData should be the body of an HTTP POST. You can deserialize it using something like:

 StreamReader reader = new StreamReader(streamId);
 String res = reader.ReadToEnd();
 NameValueCollection coll = HttpUtility.ParseQueryString(res);

It's working like that for us, at least. You may want to use a different approach to get the string into an XMLDocument or something. This works for our JSON posts. Might not be the most elegant solution, but it is working.

I hope this helps.

Glenn

Answer 4

Try this,

OperationContext.Current.RequestContext.RequestMessage