MSDN Magazine - September 2008 - (Page 80)

D ata s e r v i c e s Create Data-Centric Web Applications With Silverlight 2 shawn Wildermuth Line-of-business and other data-centric applications can be built in Silverlight™, but working with data in Silverlight isn’t always simple. While Silverlight contains many of the tools you need in order to consume data and support Web services and XML, these tools only represent the basics of data access across a firewall. A common data-access strategy uses a mix of Web services and client-side LINQ, a highly recommended approach if you’re leveraging existing Web service endpoints to power your Silverlight applications. But if you are building new Web services to work specifically with Silverlight, there is an unnecessary cost involved. this article is based on prerelease versions of silverlight 2 and aDO.Net Data services. all information herein is subject to change. this article discusses: • connecting silverlight to a data source • Using aDO.Net Data services • Using LiNQ to sQL • Debugging the service technologies discussed: silverlight 2 Beta 2, LiNQ, aDO.Net Data services code download available at: msdn.microsoft.com/magazine/cc135911 80 msdn magazine For a typical Web service layer, you implement a traditional dataaccess strategy on the server (custom business objects, LINQ to SQL, Entity Framework, NHibernate, and so on) and expose data objects through the Web service. The Web service then is merely a gateway to the underlying data-access strategy. But to enable full data connectivity, you must map the four data operations (Create, Read, Update, and Delete) to Web service methods. For example, a simple service contract to support a Product class would look something like Figure 1. (Note that I use C# throughout the article, but the code download includes Visual Basic® code as well.) It can be quite time-consuming to create a set of services to work with an application’s entire data model. And, as this example shows, feature-specific operations can cause Web service bloat. In other words, over time a Web service will have new requirements and operations added, including operations that don’t really belong to the core business domain. For instance, in Figure 1 you see the operation GetAllProductsWithCategories, which is used to retrieve the Product and include the categories by default. It wouldn’t be surprising to see sorting, filtering, and even paging mechanisms added to this simple example. It would be nice if there were a simple way to support data operations (like querying, sorting, filter, and so on) without having to continually build all these mechanisms manually. That is where ADO.NET Data Services comes in. 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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