The problem arose when i tried to call my brand new web service. I got extremely long waiting time (about 15 secs to precise), before the resource was returned. The code I used look like this:
$result = file_get_contents('http://example.com/service/');
As simple as it gets. When I tried calling the service directly from my browser, the result came back instantly.
I turned to my old friend Google to look for an answer. Most of the answers i got was that the DNS lookup was slow. So i tried my script from all the different servers I have access to, but with the same result.
The solution was quite simple, when I finally found it. In my REST-like service I set the follow header:
header('HTTP/1.1 200 OK');
By doing this I force the connection to use HTTP 1.1. This is pretty standard, but apparently by doing this I use the default behaviour of HTTP 1.1 and that is to keep the connection alive. The same as setting:
header('Connection: keep-alive');
So the connection started by file_get_contents() is keept open, until it times out. Timeout is set to 15 secs on the server!! So the solution was to put the following header in my service:
header('Connection: close');
A w00p w00p the result was returned instantly.
A quick tip if you run into this problem, and the service is not your own, is to set the header yourself. You can do this by giving a context to the file_get_contents. This can be done by doing the following:
$opts = array( 'http'=>array( header' => 'Connection: close' ));$context = stream_context_create($opts);$result = file_get_contents('http://example.com/service/', false, $context);
This will force the connection to close immediately after the resource have been retrived. Al option that can be set in a context (for HTTP) can be found here: http://php.net/manual/en/context.http.php
