This is a library that extends the PEAR HTTP_Request2 library and implements caching for the GET requests. It is written in a way where other caching mechanisms can be implemented and utilized by simply declaring that class as the request instead of HTTP_Request2 class.
This class uses the exact same interface as a typical HTTP_Request2 request, except that it uses caching for repeat GET requests.
If you wish to implement File Caching into your HTTP GET requests, you could simply use...
<?php
$request = new HTTP_FileCachedRequest('http://mysite.com/rest/resource/1234');
$result = $request->send()->getBody();
?>