Book Image

WCF 4.0 Multi-tier Services Development with LINQ to Entities

By : Mike Liu
Book Image

WCF 4.0 Multi-tier Services Development with LINQ to Entities

By: Mike Liu

Overview of this book

WCF is the Microsoft model for building services, whereas LINQ to Entities is the Microsoft ORM for accessing underlying data storage. Want to learn both? You would normally have to dig through huge reference tomes—so wouldn't you agree that a simple-to-follow practical tutorial on WCF and LINQ to Entities is the way to get ahead?This book is the quickest and easiest way to learn WCF and LINQ to Entities in Visual Studio 2010. WCF and LINQ to Entities are both powerful yet complex technologies from Microsoft—but you will be surprised at how easily this book will get you get up and running with them.Mastery of these two topics will quickly enable you to create Service-Oriented applications, and allow you to take your first steps into the world of Service Oriented Architecture without becoming overwhelmed.Through this book, you will learn what's going on behind the scenes with WCF, and dive into the basic yet most useful techniques for LINQ to Entities. You will develop three real-world multi-tiered WCF services from beginning to end, with LINQ to Entities being used in the data access layer of the services. Various clients including windows console applications, the WCF Test Client, Windows Form applications and WPF applications will be created to test these WCF services. By the end of this book, you will be 100% confident that you know WCF and LINQ to Entities, not only in theory, but with sound real-world experience.
Table of Contents (16 chapters)
WCF 4.0 Multi-tier Services Development with LINQ to Entities
About the Author
About the Reviewers

Transaction support

In the previous section we learned that simultaneous changes by different users can be controlled by using a version column or the Concurrency Mode property. Sometimes the same user may have made several changes and some of the changes might not succeed. In this case we need a way to control the behavior of the overall update result. This is handled by transaction support.

LINQ to Entities uses the same transaction mechanism as ADO.NET, that is, it uses implicit or explicit transactions.

Implicit transactions

By default, LINQ to Entities uses an implicit transaction for each SaveChanges call. All updates between two SaveChanges calls are wrapped within one transaction.

For example, in the following code, we are trying to update two products. The second update will fail due to a constraint. However, as the first update is in a separate transaction, the update has been saved to the database and the first update will stay in the database:

static void TestImplicitTransaction...