MSDN Magazine - September 2008 - (Page 27)

John PAPA Data Points Service-Driven Apps With Silverlight 2 And WCF It is true that Silverlight™ 2 makes it easy The Silverlight 2 sample application is to build rich internet applications (RIAs) made up of a handful of user controls and with tremendous graphical prowess. styles. The presentation layer communiHowever, it is also true that Silverlight cates with the server using asynchronous 2 makes it easy to build highly funccalls through WCF. It uses a WCF service tional line-of-business (LOB) applicareference to allow the Silverlight applitions. Silverlight 2 supports a subset of cation to communicate with the service the powerful XAML-based data binding according to the service’s operation conthat Windows® Presentation Foundatracts and data contracts. The data contion (WPF) enables. The XAML bindtracts (such as the Product or Category ing markup extensions in Silverlight 2 entity classes) expose the structure of simplify the process of binding entities the entities from the server application. to Silverlight controls. Because they run This makes it simple for the Silverlight completely on the client computer, Silapplication’s controls to be bound to the verlight applications are isolated from the instances of the entities and their properentities that are managed on the server. ties. The operation contracts define the Therefore service-based communica- Figure 1 The Sample Silverlight App methods that the Silverlight application tion through technologies such as RSS, can invoke on the WCF service. Figure Representational State Transfer (REST), and Windows Commu- 2 shows the high-level overview of the architecture. nication Foundation (WCF) must be available. Fortunately, SilverI began building the sample app with the lower layers, starting light 2 supports interaction with these and other communication with the WCF service itself. You can build a WCF service that can pathways, enabling Silverlight applications to interact seamlessly communicate with a Silverlight app by creating a new WCF projwith back-end LOB applications. ect in Visual Studio®. A standard WCF service can be invoked by I’ll demonstrate how to build a Silverlight 2 UI that communi- a Silverlight app as long as the Silverlight app has a binding of type cates through WCF to interact with business entities and a database. basicHttpBinding. You must either make sure you change the deThe business logic, entity model, and data-mapping code can be fault binding of the WCF service from wsHttpBinding to basicconsumed by any presentation tier. I’ll create WCF services to be HttpBinding or create a new binding of type basicHttpBinding. For consumed by a Silverlight 2 app and I’ll set up the server hosting the example, the web.config file of the sample WCF service host app WCF services to allow cross-domain invocation. Note that you can contains the following XML that defines the service configuration. download the examples from the MSDN® Magazine Web site. Notice the endpoint binding is defined as basicHttpBinding: The Sample Application Before diving into the code, let’s take a high-level look at the sample. Figure 1 shows the completed application, which displays a list of products retrieved from the Northwind database. When a product is selected from the ListBox, the product is bound to the controls on the lower half of the page. When the user edits the product through the CheckBox and TextBox controls and clicks the Save button, the product information is then sent to the database by way of WCF. Clicking on the Cancel button gets a fresh list of products from the server through WCF and updates the ListBox and its bindings. This column is based on the Beta 2 version of Silverlight 2. All information herein is subject to change. Send your questions and comments for John to mmdata@microsoft.com. Code download available at msdn.microsoft.com/magazine/cc135911. September 2008 27 http://msdn.microsoft.com/magazine/cc135911

Table of Contents Feed for the Digital Edition of MSDN Magazine - September 2008

MSDN Magazine - September 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Office Space Cutting Edge Hierarchy ID New Features for Microsoft SQL Server 2008 Prism Data Services Advanced WPF Test Run Security Briefs Foundations { End Bracket }

MSDN Magazine - September 2008

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