by mheydt
13.
December 2009 22:18
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In
part 2 I showed how to create a domain service and get the code generated for that service (heck that was automatic). In this post I'll show how to call that service from Silverlight.
In the the first post I added a reference to the Silverlight project to the Silverlight.RIA project, which will allow the Silverlight application to use those classes. I modify the MainPage.XAML to have a TextBox named 'result' and modify the MainPage.XAML.cs file to be as follows to call the service and display the result:
What's going on here? We'll, there is a whole new syntax to these calls, which I will explain briefly.
On lines 14 and 15 I add two namespaces as they are needed for the InvokeOperation (System.Windows.Ria), and the SocialBus.RIA.Web is the namespace in our RIA web project that contains the domain service.
The domain service we created is implemented by the SocialBusDomainContext class. It has a bunch of methods for managing entities, as well as the method I added to the class, 'Add'. To call the service, I create a new instance of this class, and call the 'Add' method. As is the case in Silverlight, all calls are asynchronous, so to capture the result a delegate is assigned to the method calls return value's (which is an InvokeOperation object) Completed event handler. I choose to use the lamba syntax for this, and the method is actually passed the InvokeOperation object and an EventArgs object. I cast the 's' parameter to InvokeOperation<double> (the generic is important), get the return Value, convert it to a string and assign it to the text box on the UI.
Sure, there is a lot more detail that can be covered here, such as error/exception handling and such, but this show the basics of calling the service and using the result. In the next post, I'll show how to create a POCO and pass it to the client.