16. The method of claim 15 , wherein periodically updating the indices comprises one of: initiating a polling mechanism to check for changes at the specified data source and retrieving the changes when detected for use in updating the indices; receiving push notifications from the specified data source indicating changes at the specified data source have occurred and accepting the changes for use in updating the indices; and wherein the updating of the indices occurs without requiring an active authenticated session for the subscriber.
15. The method of claim 1 , further comprising: receiving a specified data source from the authenticated subscriber; and periodically updating the indices based on the specified data source.