using ETag but the status code is always 200 and not 304

Question

When I try to request for the the http://graph.facebook.com/me?fields=friends with the ETag I always get the request code as 200 every time. we I made two back to back response and checked it. The change was at the end it had a section for pagination and it attached a access token. which is always different so the ETag value also changes. I am using google app engine to host my app. and using URLFetech to make the request.

<code> 
String ETag = FBUser.getProperty("ETag").toString();<br>
String s="https://graph.facebook.com/me?fields=friendlists&access_token=" + facebookSignedRequest.getOauth_token();<br>
URL u = null;<br>
try {<br>
u = new URL(s);<br>
} catch (MalformedURLException e) 
{
e.printStackTrace(out1);}<br>           
FetchOptions options = FetchOptions.Builder.withDefaults();<br>
HTTPRequest req = new HTTPRequest(u,HTTPMethod.GET,options);<br>
req.addHeader(new HTTPHeader("If-None-Match", ETag));<br>
URLFetchService service = URLFetchServiceFactory.getURLFetchService();<br>
HTTPResponse res = null;<br>
try 
{res = service.fetch(req);} <br>
catch (IOException e) { e.printStackTrace(out1);}<br>

String newETag="";<br>
List<HTTPHeader> Head = res.getHeaders();<br>
for(int i=0;i < Head.size();i++)<br>
{
if("ETag".equals(Head.get(i).getName()))<br>
{
   newETag=Head.get(i).getValue();<br>
   out1.println("new ETag : " + newETag);<br>
   out1.println("ETag" + ETag);<br>
}
}
if(res.getResponseCode() == 304)<br>
{ 
  return false;<br>
}else
{
FBUser.setProperty("ETag", newETag);<br>
datastore.put(FBUser);<br>
return true;<br>
}
</code>

regards,
iDeViL17

Thats what I am not able to figure out why the ETag is changing. — user2430084, May 30 '13 at 02:29
I have the same problem even I try to use RESTClient Add-on. Also I tried Firebug and Modify Headers Add-on as mentioned here https://developers.facebook.com/blog/post/627/ but the same problem. I received 200 response code in each request even I set the header correctly. Any help? — Peter T., May 11 '14 at 15:12

score 2 · Answer 1 · answered Jun 07 '13 at 23:59

I try now with request. All works:

https://graph.facebook.com/me/friends?access_token=...

First request.

DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet get = HttpGet(url);
HttpResponse = httpClient.execute(get);   
Header[] headers = httpResponse.getHeaders("ETag");   
if (headers != null && headers.length() > 0)
   etags = headers[0].getValue();

Second request:

DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet get = HttpGet(url);
get.addHeader("If-None-Match", etags);
HttpResponse = httpClient.execute(get);

using ETag but the status code is always 200 and not 304

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