Web Applications: The Virtues of Top-to-Bottom XML

I think that most people now correctly perceive our product, MarkLogic Server, as an XML content server, a special-purpose DBMS designed specifically for handling XML marked-up content. That’s the good news.

The better news is that many of these same people are figuring out what that means when it comes to developing web applications – specifically, that you can use an XML content server to build web applications using XML top-to-bottom. No Java required. No relational tables required. No application server required. (And no expense for all those supporting products.)

Don’t get me wrong. Many customers choose to use MarkLogic as the XML repository and query system in their architecture, building their applications in Java, using an application server, and making calls out to MarkLogic to process XML queries. Lots of people use the product in that way. That’s fine.

But, people soon realize, when you have a DBMS and query language (XQuery) that directly outputs XML (e.g., xHTML) which can be directly rendered by a browser, and when that “query” language is really a misnamed and underpositioned programming language easily capable of developing entire applications, you can say:

Good question. And the answer is you can. And in many cases, you probably should. What’s the advantage of so doing?

• Use of a high-level, standard, powerful programming language, XQuery. High-level and powerful translate to greater development and maintenance productivity. Standard translates to risk reduction and freedom of choice. (Aside: While XQuery is not a big-hype, overnight-success type of technology like Ajax, XQuery continues to march along with certain inevitability. In my mind, there is no question that XQuery will be the database programming language of the future – it is superior to SQL, it is more general than SQL and ergo applicable to a broader class of problems, and all major DBMS vendors are already committed to it. The question is not will XQuery become mainstream, but when?)

• Elimination of three impedance mismatches: Java/XML, XML/relational, and Java/relational. Java is object-oriented, XML is hierarchical, and relational databases are tabular. The mapping between these three different data models generates a lot of zero-value-added work in developing an application. When you’re XML top-to-bottom, poof, that work’s all gone.

• Elimination of tiers. I had lunch a while back with a top engineer at Oracle who told me that he believed the limiting factor on database application performance was becoming scheduling. That is, hardware and databases are becoming so fast that scheduling work across tiers was becoming the limiting factor in performance. His suggested solution? Eliminate tiers. Well top-to-bottom XML does exactly that.