XML-RPC is Easy

The XML-RPC interface uses... well... xml-rpc. You'll be using a library, surely. The endpoint is http://api.jaiku.com/xmlrpc

All parameters should be sent as a dictionary, which means one big argument that is a list of key-value pairs rather than positional arguments (this makes it easier to deal with defaults)

An example actor_get call (from python):

import xmlrpclib
from oauth import oauth
consumer = oauth.OAuthConsumer('consumer key', 'consumer secret')
access_token = oauth.OAuthToken('access token key', 'access token secret')
xmlrpc_url = 'http://api.jaiku.com/xmlrpc'
params = {'nick': 'jaiku'}
request = oauth.OAuthRequest.from_consumer_and_token(
    oauth_consumer=consumer,
    token=access_token,
    http_url=xmlrpc_url,
    http_method='POST',
    parameters=params)
request.sign_request(
    oauth.OAuthSignatureMethod_HMAC_SHA1(),
    consumer,
    access_token)
server = xmlrpclib.ServerProxy(xmlrpc_url)
rv = server.actor_get(request.parameters)
print rv

And the expected result should look like:

{'actor': {'avatar_updated_at': '2009-01-01 00:00:00',
           'extra': {'follower_count': 81397,
                     'family_name': 'Team',
                     'given_name': 'Jaiku',
                     'contact_count': 52,
                     'icon': 'jaiku@jaiku.com/avatar_15'},
           'privacy': 3,
           'nick': 'jaiku@jaiku.com',
           'deleted_at': None,
           'type': 'user'}}

To find out more about the OAuth consumer and access token, check out Authentimacatoritization

About legacy authentication support...

The XML-RPC interface also works with legacy credentials. You need to replace the OAuth parameters the following variables:

user           # user's nick
personal_key   # generated by the legacy authentication system