There are a lot of information how to build Silverlight application using .NET RIA services, but it isn't clear what is unique thing in RIA that is absent in WCF?

Here are few topics that are talking around this topic: http://stackoverflow.com/questions/1647225/ria-services-versus-wcf-services http://stackoverflow.com/questions/945123/net-ria-services-wcf-services

But they doesn't give an answer to the question.

Sorry for the stupid question, but what does "RIA Services" layer bring into your app if you already have "Silverlight <--> WCF Service <--> Business Logic <--> Entity Framework Model <--> Database"? Authentication? Validation? Is it relly asset for you?

At the moment the only thing I see: with RIA services usage you don't need to host WCF service manually and don't need to configure any references on the client side (clien side == Silverlight application).

Probably I don't know some very useful features of the RIA Services? So could you please point me to the good doc for that?

Many thanks.