Introduction
============

``pydataportability.discovery`` is a component for discovering resource description
documents. These are `XRD documents <http://code.google.com/p/webfinger/wiki/XrdFiles>`_ describing 
a resource and optionally pointing to related resources. One use case is the 
`webfinger project <http://code.google.com/p/webfinger/>`_ where XRD is used to store
information about a user. The URI identifying the user is e.g. ``acct:user@example.com``
and this discovery component is able to retrieve information about the user via
`LRDD <http://hueniverse.com/2009/03/the-discovery-protocol-stack/>`_.


Installation
------------

The easiest way to install it is via ``easy_install``::

    easy_install pydataportability.discovery

It is recommended to do this inside a `virtualenv <http://pypi.python.org/pypi/virtualenv/1.3.4>`_


Simple usage
------------

After installing you will have 2 new commands in your path (or virtualenv's ``bin/`` directory):
``discover`` and ``webfinger``. These are just example scripts though. Both do discovery
on the URI you feed in but the latter will check for webfinger-relationships only and will
additionally check if you passed in a user identifier starting with ``acct:`` which is the
proposed scheme of the webfinger protocol. If you didn't, it's adding it for you.

Here is an example::

    $ webfinger someuser@googlemail.com

    Subject:  acct:someuser@googlemail.com

    Rels:  ['http://portablecontacts.net/spec/1.0']
    URIs: ['http://www-opensocial.googleusercontent.com/api/people/']
    Media Types: []
    Prio: 0
    Templates: []

So this mainly prints the contents of the discovered XRD document. Note that the
user you are testing it with needs to enable this at Google. Check out the 
`webfinger homepage <http://code.google.com/p/webfinger/>`_ and 
`mailing list <http://groups.google.com/group/webfinger/>`_ for more information.


Documentation 
-------------

You can find the documentation for this component at http://dataportability.net

.. warning:: Note that the XRD specification and the webfinger protocol are under heavy
   development and likely to change. 

License
=======

This project is released under a BSD license:


Copyright (c) 2009, Christian Scholz
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
following conditions are met:

 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following
   disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided with the distribution.
 * Neither the name of the author nor the names of its contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.

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