Distutils2 queries PyPI to get information about projects or download those projects. The low-level facilities used internally are also part of the public API destined to be used by other tools.
The distutils2.index package provides those facilities, which can be used to access informations about Python projects registered at indexes, the main one being PyPI, located ad http://pypi.python.org/.
There is two ways to retrieve data from these indexes: using the simple API, and using XML-RPC. The first one is a set of HTML pages avalaibles at http://pypi.python.org/simple/, and the second one contains a set of XML-RPC methods. Mirrors typically implement the simple interface.
If you dont care about which API to use, the best thing to do is to let distutils2 decide this for you, by using distutils2.index.ClientWrapper.
Of course, you can rely too on distutils2.index.simple.Crawler and distutils2.index.xmlrpc.Client if you need to use a specific API.