While exploring Map api integration with SOI application, I felt that a separate article on consuming external web services from a SL application is worth writng. As we know, services can be SOAP based (WCF bases) or can be REST (Simple HTTP) based on their implementation. As you goggle you will find many services from different providers; here you can find some of them (webservice directory). Some might be useful; saving lots of time and some may look fancy. Silverlight can access some services directly for e.g HTTP/REST type and some using proxy for e.g. SOAP. Well before describing the process let's have a look at a web service in Silverlight. Services hosted by various host come with various security policies for e.g yahoo allows access to it's services for authenticated requests only and authentication can be achieved by using OpenID, Oauth and Hybrid (Yahoo API Auth.); similarly Google services. These external service administrators create policy files to restrict the request from other domains without proper authentication.