Beginning Python - From Novice to Professional

338 CHAPTER 15 ■ PYTHON AND THE WEB
>>> from xmlrpclib import ServerProxy
>>> server = ServerProxy('http://coversproject.com/RPC.php')
>>> covers = server.covers.Covered('Monty Python')
>>> for cover in covers:
... if cover['song'] == 'Brave Sir Robin':
... print cover['artist']
...
Happy Rhodes
The ServerProxy object looks like a normal object with various methods you can call, but
in fact, whenever you call one of its methods, it sends a request to the server, which responds
to the requests and returns an answer. So, in a way, you’re calling the method covers.Covered
on the server itself. Network programming could hardly be any easier than this. (For more
information about the XML-RPC methods supplied by The Covers Project, see http://
coversproject.com/about/xmlrpc.html.)
■Note XML-RPC procedure (function/method) names may contain dots, as in the preceding example. The
name covers.Covered does not imply the existence of an object named covers on the server—the dots
are only used to structure the names.
Here is a slightly more complicated example, which uses the news service Meerkat to find
some articles about Python:
>>> from xmlrpclib import ServerProxy
>>> query = {'search': 'Python', 'num_items': 5}
>>> s = ServerProxy('http://www.oreillynet.com/meerkat/xml-rpc/server.php')
>>> items = s.meerkat.getItems(query)
>>> [i['title'] for i in items]
['MacHack: Meet Dylan the Yoot', 'Hap Debugger', 'Project and proposal for
integrating validation with processing pipelines', 'Spam Check', 'ZCoMIX 1.0
Final Released']
>>> items[0].keys()['link', 'description', 'title']
>>> items[3]['link']
'http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/134945'
As you can see, the method meerkat.getItems is called with a mapping parameter that
contains various arguments (in this case a search query and the number of items to be returned)
and returns a list of mappings, each of which has a title, a description, and a link. Actually,
there is a lot more to Meerkat than this—if you want to experiment, take a look at the Meerkat
Web site (http://www.oreillynet.com/meerkat) or one of the many online tutorials about
the Meerkat XML-RPC API (for example, http://oreillynet.com/pub/a/rss/2000/11/14/
meerkat_xmlrpc.html).