This print for content only-size & color not accurate 7" X 9-1/4" / casebound / malloy

■

Note

This chapter will provide you with a firm foundation in WCF development. However, if you require a com-

prehensive treatment of the subject, check out Pro WCF: Practical Microsoft SOA Implementation by Chris Peiris

and Dennis Mulder (Apress, 2007).

A Potpourri of Distributed Computing APIs

The Windows operating system has historically provided a number of APIs for building distributed

systems. While it is true that most people consider a “distributed system” to involve at the very least

two networked computers, this term in the broader sense can simply refer to two executables that

need to exchange data, even if they happen to be running on the same physical machine. Using this

definition, selecting a distributed API for your current programming task typically involves asking

the following pivotal question:

Will this system be used exclusively “in house,” or will external users require access to the

application’s functionality?

If you are building a distributed system for in-house use, you have a far greater chance of

ensuring that each connected computer is running the same operating system, using the same pro-

gramming framework (.NET, COM, J2EE, etc.), and you will be able to leverage your existing security

system for purposes of authentication, authorization, and so forth. In this situation, you may be

willing to select a particular distributed API that will tie you to a specific operating system/

programming framework for the purposes of performance. 

867

C H A P T E R   2 5

8849CH25.qxd  10/16/07  10:51 AM  Page 867

---

In contrast, if you are building a system that must be reached by those outside of your walls,

you have a whole other set of issues to contend with. First of all, you will most likely 

not be able to

dictate to external users which operating system they make use of, which programming framework

they use to build their software, or how they configure their security settings. 

Furthermore, if you happen to work for a larger company or in a university setting that makes

use of numerous operating systems and programming technologies, an in-house application sud-

denly faces the same challenges as an outward-facing application. In either of these cases, you need

to limit yourself to a more flexible distributed API to ensure the furthest “reach” of your application.

Based on the answer to this key distributed computing question, the next task is to pinpoint

exactly which API (or set of APIs) to make use of. By way of a painless overview, the following sec-

tions present a quick recap of some of the major distributed APIs historically used by Windows

software developers. Once you finish this brief history lesson, you will easily be able to see the use-

fulness of Windows Communication Foundation.