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.NET Web services: the `Three I'' monster: Web services ... middleware for the masses ... XML miracle tools ... instant integration: just add SOAP. (xml & web services).

Article Excerpt
As readers of a magazine focused on XML, it may amuse many of you that the world has suddenly discovered what we've known for almost six years: XML is a massively powerful metalanguage. Nowhere is that proven better than in the sudden explosion of Web services in the marketplace.

Microsoft embraces Web services as an important component of their .NET framework, but rather than take it on as an afterthought, Microsoft went out of their way to make Web services both simple and pervasive. Indeed, XML itself is the lifeblood of .NET, with major components easily communicating back and forth, using XML when needed. Data persistence is also gracefully handled in the back end of .NET applications in XML, with a minimum of programming. What makes XML in the .NET framework so pleasant is that all of these features are easy to use and powerful. Going a step further, Microsoft's Visual Studio tool makes designing XML schemas a snap. What this means is that XML has finally been promoted out of buzzword status and into the real world, and the pack leader is Web services.

For good or bad, the term Web services is going to stick. I find that unfortunate, because the only thing that's really "Web" about them is that they can communicate over HTTP, the common transport protocol of the Web. As time progresses, we'll see more efficient protocols replacing HTTP for Internet communication, but most likely they'll still be called "Web services." In reality, Web services are integration components (a concept analogous to the hardware IC -- a "software chip," if you will). Web services can do any combination of three things: Inform, Inquire, and Invoke. (Want a really good mnemonic? Remember "IC the 31 Monster"!)

So how can we make sense of the Web services acronyms then: UDDI, WSDL, and SOAP? Let's do it the way I like, using the All-you-need-to-know-about-Web-services-acronyms-in-one-paragraph method.

Are You Ready?

Let's use the process of faxing as an analogy. A Web service informs a centralized directory that it exists, like putting a fax number in a phone book. Another Web service might inquire about how to use another Web service, like looking up a number in a phone book. A Web service then invokes another service, like dialing a fax number. The fax is finally transmitted, and the client receives a "special package offer" for a vacation in the Bahamas. Now that you have the fax analogy in your head, here's how the Web services acronyms fit together: UDDI = phone book, WSDL = fax number, SOAP = a faxed page, and HTTP = telephone-carrier signaling. There. All done! For those that want some more details, the next few paragraphs should help a little.

UDDI -- Universal Description, Discovery, and Integration -- is a mechanism to store and publish...

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