Listing 6 shows a header request specifying that only data that has been modified since November 11, 2003 be sent back from the server.

Going back to Listing 14, after we create the XML document as a string, we set the response header for the content type and send the XML string back to requester.

Originally, the purpose of this header was to identify the intent of the request — the operation to be invoked on the back end.