Introduction to WCF Concepts - WCF Services (Page 2 of 4 )
WCF services are the new distributed boundary in an enterprise application--with an emphasis on SOA. In the past, you had to deliberate between Enterprise Services, .NET Remoting, or ASMX to distribute and reuse functionality, WCF provides you with a single programming model to satisfy the needs of any equivalent distribution scenario. With WCF, you can cross process, machine, and corporate boundaries over any number of protocols; you can expose interoperable web services; and you can support queued messaging scenarios. I'll take you through a few examples where WCF is deployed in lieu of earlier technologies.
Figure 1-11 illustrates an intranet scenario where a WCF service is invoked within an application domain over TCP protocol. In this scenario, the client needed to reach remote services and authenticate with Windows credentials, and didn't require interoperability. As such, the service is accessible over TCP using binary serialization for better performance, and supports traditional Windows authentication using NTLM or Kerberos. In the past, this may have been achieved using Enterprise Services (or possibly .NET Remoting although security features are not built-in).
Figure 1-12 illustrates an Internet scenario where multiple web services are exposed--one supporting legacy protocols (Basic Profile), another supporting more recent protocols (WS*). With WCF, a single service can be defined and exposed over multiple endpoints to support this scenario.
Figure 1-11. Deploying WCF services on the intranet
Figure 1-12. WCF services exposed on the Internet
In Figure 1-13 you can see WCF implemented at several tiers—behind the firewall to support an ASP.NET application, and outside the firewall for smart client applications. Again, the same service can be exposed over multiple protocols without duplicating
effort or switching technologies.
Figure 1-13. WCF services deployed at several tiers over multiple protocols
Throughout this book, I’ll be exploring these and other scenarios while discussing specific features of the WCF platform.
Next: Fundamental WCF Concepts >>
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 This article is excerpted from chapter 1 of the book Learning WCF A Hands-on Guide, written by Michele Leroux Bustamante (O'Reilly, 2007; ISBN: 0596101627). Check it out today at your favorite bookstore. Buy this book now.
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