The beauty of Astoria is that it exposes the model without having to write dozens or hundreds of service methods to do so. Instead, it exposes the model thorugh a series of unique URI's that are mapped to the domain entities. For example http://mydomain/myservice.svc/customer(101)/orders?orderby=orderdate could return a list of orders for the customer with an ID = 101 sorted by order date. The data can be returned as XML or JSON, too. No service is written on the server side to handle this specific action, instead Astoria handles the mapping to the entities and offers a set of operators such as orderby and filter that can massage the data. Its a pretty slick concept overall, especially for those who love REST. The advantage here is that you don;t have to write a lot of RESTful web service methods to do this, since Astoria does that work for you iunder the covers.

Calling Astoria ... this can be done through any HTTP web request by passing a URI. Or, if you use Silverlight 2, you can use the Silverlight client library for Astoria which allows you to write a LINQ query to operate on the entities using the LINQ query syntax. the query is examined by the client library and turned into the URI / HTTP request. So in the end it works the same. The client library just allows a developer to make a simple request using the well known LINQ syntax if available.If you don;t want to use LINQ, you can still make a standard HTTP web request, too. There are lots of options, which is always good!