MrDave's (David Yack) Blog!

I’ve been playing around for a few month’s with a Silverlight Twitter Client.  It uses a WCF proxy to access the Twitter service because Twitter does not publish policy files.  The proxy also handles some of the hard work so the Twitter client just consumes a nice object model instead of the REST XML produced by Twitter.

Anyway, all of a sudden my posts stopped posting to Twitter and the Twitter server started returning the following:

The expectation given in the Expect request-header field could not be met by this server.

So after a little research it would appear that WCF is adding that by default to the header sent.  You can read more about  the 100-continue here in the spec.

There’s a couple ways to deal with this, I handled it by setting the property on the HttpWebRequest.  If you were dealing with a WebRequest object instead of a HttpWebRequest you would need to cast it to access the property.

((HttpWebRequest)webRequest).ServicePoint.Expect100Continue = false;

You can also modify the default behavior by setting the Expect100Continue property on ServicePointManager

System.Net.ServicePointManager.Expect100Continue = false;

If you want to connect on twitter you can find me at http://twitter.com/davidyack