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
Credits
About the Author
About the Reviewers
Preface
Index

Adding error handling to the service


In the previous sections, when we were trying to retrieve a product but the product ID passed in was not a valid one, we just threw an exception. Exceptions are technology-specific and therefore are not suitable for crossing the service boundary of SOA-compliant services. All exceptions generate a fault on the communication channel, resulting in unhappy proxies, as a recover and retry is not possible. Thus, for WCF services, we should not throw normal exceptions.

What we need are SOAP faults that meet industry standards for seamless interoperability.

In the service interface layer operations that may throw FaultExceptions must be decorated with one or more FaultContract attributes, defining the exact FaultException.

On the other hand, the service consumer should catch specific FaultExceptions to be in a position to handle the specified exceptions.

Adding a fault contract

We will now change the exception in the GetProduct operation to a FaultContract.

Before...