Designing Silverlight Business Applications: Best Practices for Using Silverlight Effectively in the Enterprise

11. The Service Layer

APPLICATION SERVICES LIVE IN THE MODEL PORTION OF YOUR application and help facilitate interaction with the back-end systems. Although the term service has almost become synonymous with web service, many service classes have nothing to do with SOAP and don’t require a network connection. Data access services provide the façade for their underlying persistence mechanisms; security services handle authorization and authentication concerns; and validation services provide integrity for data within the system.

The service layer is perhaps the most important aspect of your application. It is the M in MVVM that the view models depend on to synchronize presentation logic with the rest of the application. It is where your data models ...