Chapter 20 -- An XML Overview

[Previous] [Next]

Chapter 20

Paul Maritz, a group vice president at Microsoft, said at TechEd 99 that it's hard to exaggerate the importance of the Extensible Markup Language (XML) standard. In his talk, he presented a vision of a third-generation Internet architecture that would allow Web servers to exchange information without the use of HTML. He said that he and Microsoft were convinced that an important part of such an architecture would be XML.

He emphasized the conceptual simplicity of XML and also said that XML will revolutionize Web usage and be a driving force in the integration of general applications and e-commerce applications. XML is so simple that Peter J. (Peet) Morris has referred to it as "ASCII with tags," saying that "it does practically everything required while still being far simpler than SGML [Standard Generalized Markup Language], the full markup specification on which it is based."

You'll see in this chapter that quite a lot of support for XML exists in standard technologies such as Extensible Stylesheet Language (XSL), the XML Document Object Model (XML DOM), the XML Data Source Object (DSO) for data binding, and many others. If you visit a bookstore, you can easily find books about XML, such as Alex Homer's XML IE5 Programmer's Reference and William J. Pardi's XML in Action, two books that we've used a lot and recommend. Visiting Microsoft's and other vendors' Web sites can also render quite a lot of information about XML and related technologies.

But to be honest, you won't yet find many tools that make XML development easy. What you need is XML support all the way from the database to the client and all the way back to the database again, and that support just isn't there yet. Will it come? Yes, yes, yes! We're writing this paragraph in January 2000, and about a year from now you'll have all the support you need for XML in all possible tiers of your Microsoft Windows DNA 2000 applications. The two of us firmly believe in this, and neither of us believes in Santa Claus.

Microsoft has already taken the first step, in supplying the XML support inherent in version 2.5 of ADO, the new ADO version that ships together with Windows 2000. (As you read this, Microsoft has probably also made ADO 2.5 available for download from its Web site.) Anyway, ADO 2.5 lets you fetch a recordset from a database such as Microsoft SQL Server the same way you've been able to do with earlier versions of ADO. What's new is that you can save the structure and content of that recordset as an XML string to a variable. You can also convert a properly structured XML string to an ADO recordset, using that recordset to update the database again. We'll tell you about that functionality in Chapter 21, "XML with ADO 2.5 for Our Components."

This is a small step toward full XML support, but because it's the first support of its kind, it's an important step. The next step comes when Microsoft begins to ship SQL Server 2000, which as we write this is the next version of Microsoft's flagship database management system, SQL Server. At this time, just about the only thing Microsoft has made public about SQL Server 2000 is its XML support, so we'll be able to tell you just a little bit about that as well; we'll do that in Chapter 21 too.