WCF RIA service is a framework to develop n-tier application for Rich Internet Application (RIA). It is mainly used in RIA applications like Silverlight, AJAX client, etc. It solves the major problem while developing business application like decoupling the resource access, application logic and presentation layer. WCF RIA service was introduced in Silverlight 4 with .net framework 4, and it can be developed using visual studio2010.
Main problem developer are facing while developing the n-tier RIA application will be coordinating the application logic between middle tier and presentation tier. This problem will be solved by using WCF RIA service, it will synchronize the code between middle and presentation tier.
WCF RIA service will allow developer to write the set of service code and this server code will be available to the client side without manually duplicate that programming logic. RIA service client will be updated with business rule and entity present at the server side, when your recompile your project solution.
WCF RIA service will generate the code at the client side related to the service and domain entities declared at the server side.
RIA service exposes the data from server side to client side using Domain service, RIA service framework implements the each domain service as WCF service to access the data as business entity.