How to read HTTP header from response using .NET HttpWebRequest API?

Question

My app currently uses OAuth to communicate with the Twitter API. Back in December, Twitter upped the rate limit for OAuth to 350 requests per hour. However, I am not seeing this. I am still getting 150 from the account/rate_limit_status method.

I was told that I needed to use the X-RateLimit-Limit HTTP header to get the new rate limit. However, in my code, I do not see that header.

Here is my code...

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(newURL);
request.Method = "GET";
request.ServicePoint.Expect100Continue = false;
request.ContentType = "application/x-www-form-urlencoded";

using (WebResponse response = request.GetResponse())
{
    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
    {
        responseString = reader.ReadToEnd();
    }
}

If I inspect the response, I can see that it has a property for Headers, and that there are 16 headers. However, I do not have X-RateLimit-Limit in the list.

_{(source: yfrog.com)}

Any idea what I am doing wrong?

Blazonry

I dont know anything about twitter API, but shouldn't the X-RateLimit-Limit header used in Request, not recieved wia Response? – Odious

@Yossarian, no; it should be in the response: apiwiki.twitter.com/Rate-limiting – Commensurable

@Yossarian - the request only has two headers: Content-Type and Host. And those are RequestHeaders. The X-RateLimit-Limit comes from Twitter, so I would have assumed it would be in the response. – Blazonry

Answer 1

Look at the raw response text (e.g., with Fiddler). If the header isn't there, no amount of C# code is going to make it appear. :) From what you've shown, it seems the header isn't in the response.

Update: When I go to: http://twitter.com/account/rate_limit_status.xml there is no X-RateLimit-Limit header. But when I go to http://twitter.com/statuses/public_timeline.xml, it's there. So I think you just need to use a different method.

It still says 150, though!

Commensurable

Thanks Craig. The problem is that the rate_limit_status is not rate limited. Neither was the method I was using (the access_token OAuth Method). If I use a method that is rate limited, like the public_timeline, it's there. So it seems that Twitter only sends those header values for methods that are actually rate limited. – Blazonry

Answer 2

You should simple be able to use:

using (WebResponse response = request.GetResponse())
{
  string limit = response.Headers["X-RateLimit-Limit"];
  ...
}

If that doesn't work as expected, you can do a watch on response.Headers and see what's in there.

Pushy

It's working not, if the Response is not an 200 OK. If the server gives an 550 Internal Server Error or an 404 Not Found, the application will break with an Exception on GetResponse. – Bighead