How can I tell if Heroku is sending gzipped responses?

Question

I'm making an iPhone application that requests JSON from Heroku.

1. Am I getting a gzipped response? And, does the iPhone automatically unzip gzipped responses, or do you have to program that in? I'm using NSURLConnection asynchronously (with the delegate protocol) as described in the Xcode docs.

   When I do:

   curl -I http://acani.heroku.com/users/4c96ee4f1467281352000049/1234/50/50
   

   I get:

   HTTP/1.1 200 OK
   Server: nginx/0.7.67
   Date: Sun, 17 Oct 2010 16:27:25 GMT
   Content-Type: application/json
   Connection: keep-alive
   Content-Length: 11532
   X-Varnish: 2314841869
   Age: 0
   Via: 1.1 varnish
   

2. I'm also using the Zimt WebSocket code with AsyncSocket for chat. The chat server is Node.js. Should I be gzipping each chat message? Or is that done automatically?

3. I wonder, to reduce bandwidth, does Twitter gzip your tweets (with JavaScript on the web, or Objective-C on the iPhone) before they are sent to Twitter?

Thanks!

Matt

Answer 1

To detect if a response is compressed or not, you need to look for a Content-Encoding header. It can be set to either gzip, compress, or deflate. See RFC 2616 Section 3.5 for more details.