Ok, all these methods of getting data in a Silverlight control are confusing me.
I've looked at ADO.Net Data Services, Web Service and Silverlight-enabled WCF services.
I'm just not sure when one is appropriate to use over another. What pros/cons do each offer?
I've built a web app, and a Silverlight control. I will be adding one of those 3 options to my web application and consuming it from my Silverlight component.
Best Answer
From the silverlight perspective, WCF is heavily constrained anyway, so most of the usual benefits of WCF don't apply. However, it is still a fairly nice, consistent programming model.
WCF is primarily a SOAP stack, so it is very good at presenting data as rigid operations. ADO.NET Data Services is a REST stack, and allows very expressive queries to be performed dynamically over the wire.
I don't know how it is in Silverlight, but a regular ADO.NET Data Services proxy (the bit on your client app) has very rich support for both query and data changes back to the server. Note that applying changes requires either a: Entity Framework, or b: lots of work. But you should get query and update very cheaply with this approach.
With WCF, you get a much more controlled stack, so you will need to code all the distinct operations you want to be able to do. But this also means you have a known attack surface etc; it is much harder to exploit a locked down API like a fixed SOAP endpoint.
Re regular web-services (pre-WCF): only go down that route if you want to support very specific legacy callers.