MSDN Magazine - July 2008 - (Page 25)

John PAPA Data Points The Entity Framework In Layered Architectures When architects of an n-tiered architecture evaluate any new technology, pattern, or strategy, they have to consider how that new piece of the puzzle is going to mesh with the architecture. With the Entity Framework, integration is not a problem. It can be integrated into an n-tier architecture as well as a single-tier architecture. In this month’s column I will demonstrate how the Entity Framework can fit into an n-tier architecture that uses Windows® Communication Foundation (WCF) and Windows Presentation Foundation (WPF) technologies and the Model View Presenter (MVP) pattern. I will present a sample architecture that contains layers for a logical store database, data access, a domain model, a business manager, a service layer, a presentation layer, and a passive UI layer, and I will demonstrate how these layers integrate using the Entity Framework. All of the code examples I use are available for download from the MSDN® Magazine Web site. Defining Layers The application I’ll present allows a user to search for customers in the NorthwindEF sample database Figure 1 Architectural Overview and view, add, edit, or delete them. Before diving into the code and the examples, let’s discuss the overall architecture of WCF using the service’s contract as a guide. The service layer exposes the sample. Because my focus is not the architecture itself, but how its services through service contract interfaces. These contracts alto integrate the Entity Framework with an architectural design, I low the presenters to be certain of how to call the services. The service layer is responsible for receiving the communicachose a relatively common architecture that can be modified and tions from the presenters and calling the appropriate business layintegrated fairly easily with other strategies. Figure 1 shows a high-level view of a typical layered architecture. er methods that will execute appropriate business logic and data The top two layers handle the user interface presentation and navi- gathering or modifications. The business layer is where the business gation using a UI layer and a presentation layer. The UI layer can be logic and the LINQ to Entities code for this project would reside. implemented in any one of a variety of technologies; however, for The LINQ to Entities code will reference the entity model that is this column and its examples I will use WPF. The UI layer follows generated from the Entity Framework. When the LINQ queries the MVP pattern with a passive view, which means that the views are executed, the Entity Framework will translate the LINQ query (the top UI layer) are managed and directed by the presentation layer. The presenters are responsible for giving the views their data, This column is based on a prerelease version of the ADO.NET Entity pulling data from the views to be saved in the lower layers, and in Framework. All information herein is subject to change. general for responding to events raised by the views. Send your questions and comments for John to mmdata@microsoft.com. The presenters communicate with the lower tiers through WCF Code download available at msdn.microsoft.com/magazine/cc135911. in my example here. A presenter will invoke a service through July 2008 25 http://msdn.microsoft.com/magazine/cc135911

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

MSDN Magazine - July 2008 Contents Toolbox CLR Inside Out Flex Your Data Data Points Advanced Basics Office Space Cutting Edge Data Services ADO.NET Data and WPF Transactions WCF P2P Test Run Security Briefs Foundations .NET Matters {End Bracket}

MSDN Magazine - July 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.