Sending post to creation factory on RTC but getting a 'GET' response

Question

I've hit a strange bit of behaviour and I'm pretty sure is related to my code rather than the RTC instance I'm working with.

I've got a web request setup and configured:

var cookies = new CookieContainer();
var request = (HttpWebRequest)WebRequest.Create(getCreationFactoryUri);
var xmlString = getRDF.ToString();

request.CookieContainer = cookies;
request.Accept = "application/rdf+xml";
request.Method = "POST";    
request.ContentType = "application/rdf+xml";
request.Headers.Add("OSLC-Core-Version", "2.0");
request.Timeout = 40000;
request.KeepAlive = true;
byte[] bytes = Encoding.ASCII.GetBytes(xmlString);
request.ContentLength = bytes.Length;
Stream dataStream = request.GetRequestStream();
dataStream.Write(bytes, 0, bytes.Length);
dataStream.Close();

This is passed to another method wrote based on an RTC example using forms authentication for RTC.

Under the OSLC v2 spec, I'm using a creation factory URL to post to. I know the URL is fine because I've setup a call using RESTClient in Firefox. Added the headers that are needed (Content-Type: application/rdf+xml, Accept: application/rdf+xml, OSLC-Core-Version: 2.0) and used the generated XML that my code is trying to pass. My manual call works perfectly and the ticket is created.

In my logs I captured the response from RTC, which is a list of tickets rather than a response showing my ticket as being created. I can re-create this behavior by doing a GET on the creation factory URL I'm using to create an event ticket.

So although I know I'm sending a POST to the creation factory (I debugged to check that my web request method was 100% set to 'POST') RTC instead returns a list of tickets and I can only conclude somewhere my request is treated as a 'GET'.

As a test I changed my request to use PUT instead of POST. This isn't permitted for use on the creation factory URL and in testing it indeed throws an error. So I'm totally miffed as to why RTC isn't creating my ticket, but instead treating my request as a GET and returning a list of tickets.

Anyone have any ideas?

Thanks.

Answer 1

If the server using form authentication, as you state, then I expect what is happening is that the POST is resulting in an HTTP redirection to the authentication form. Even if your other code is handling that authentication (which it sounds like it is), the result of that authentication will be an HTTP redirection to the URL of the original request. However, that redirection is likely to result in a GET to that URL, not the original POST. (Also, I don't believe the redirection after authentication is 100% reliable, if your requests are multi-threaded).

The jazz.net information on form authentication says "After authentication succeeded, you always have to replay the original request at least once to get to the protected resource. More replays may be required if the first replay led to another set of redirections and the original request had a non-GET method."

So if your code received an authentication challenge, you will need to re-send the original POST.

I believe the reason why the RESTClient plug-in in your browser is working first time is that it is sending the cookies from your previous log-in to the RTC web UI in the browser. (I had this experience recently, and also found it very confusing).

Also, if you are not preserving cookies between requests to RTC in your client app, then you will meet an auth challenge for every request. If you preserve cookies between calls from your client app (how you do that will depend on your client library - I'm not familiar with the code in your examples) then my experience is that you won't receive an auth challenge for every request. (However, you still need to be able to handle an auth challenge on every request - including POSTs - otherwise it may fail intermittently if the session times out just before you send a POST).