== Intro ==

This package is an early-release of the webhooks / publish-subscribe
protocol that http://pubsubhubbub.googlecode.com/ is working and
rapidly deploying for various Google services.

The protocol itself isn't tied or limited to a Google service; a
number of hubs have been created and deployed already (see the
above URL for list.)

This Haskell package adds support for working with these
HTTP-based publish-subscribe hub servers, i.e., you may
subscribe to notification to URLs ('topics') from a hub and it
will push updates down as they occur (rather than you polling.)

== Getting started ==

The protocol is dependent on having some callback/endpoints
to forward 'topic' updates to you locally. There's a number of
ways of providing this in Haskell...for testing purposes, I've
included a 'fastcgi' proxy/relaying script that handles this;
see examples/Main.hs It operates by forwarding incoming requests
to a local server for processing -- the thinking being that
it provides a robust web front-end, leaving your basic Haskell
code to do the interesting bits of proccessing the pubsub
notifications. An example of how this could be done is provided
in examples/Feeder.hs which uses the pubsubhub service that
superfeedr.com provides.

To use, you need to:

 * build the cabal package..(!)
 * Make the fastcgi script pubsub.fcgi available on
   'web-visible' URL. 
 * Adjust the settings at the top of examples/Feeder.hs
   to match your local settings for the script's URL +
   settle on a hub to use.

For actual code / documentation on the bits that implement the
very-straightforward PubSubHub protocol, see Web/PubSub.hs


enjoy
--sigbjorn 09/08/2009