Coherity's take on the XML Database

By Dave Kearns
Network World Directories Newsletter, 08/07/02

The term "XML Database" can conjure up numerous images. It could be an SQL-enabled relational database system used to track XML elements. Or it could be a database system whose schema consists of XML statements.

When Network World's John Cox wrote about them last January, he mentioned that "There's no formal, standard definition of an XML database," but in general it means a database system designed for querying via XML statements. As Cox put it, "The key point is the database 'thinks and acts' based on XML - XML goes in, and XML comes out."

"Working out the bugs in XML Databases" www.nwfusion.com/news/2002/0107specialfocus.html

With those thoughts in mind, I sat down to chat with Coherity founder and CTO Joe Ellsworth, along with Ken Tsai, the company's director of product marketing. We were supposed to be talking about the company's XML Database product, but I opened by asking Ellsworth to give me a brief bit of background.

The project that gave rise to the product and company, he said, was an outgrowth of a problem Hewlett-Packard was facing. It seems HP had 30 separate programs designed to interact with clients, vendors and customers through various Web sites. Users were complaining about the need to log on to each site, even when jumping from site to site. They also couldn't understand why they needed to keep entering information (addresses, phone numbers, preferences, etc.) to each of the HP sites they visited.

You'll recognize, of course, that what was needed was a good virtual directory system with single sign-on options.

Unfortunately (from the directory perspective), Ellsworth and his team were Python programmers. "Python is an interpreted, interactive, object-oriented programming language. It is often compared to Tcl, Perl, Scheme or Java," according to www.python.org. More importantly, it's tightly intertwined with XML (for no apparent reason except happenstance, as far as I can tell).

So, Joe and his crew set out to solve the problem and effectively created a virtual directory system. But they called it an XML Database. They knew that they were storing data for use by the various applications, so it must be a database that they created. They also knew that all communication with the database would be in XML - mostly because it's easier to retrofit an application with XML than it is to rewrite the application.

Ellsworth, without knowing the first thing about virtual directory servers, described an entity remarkably similar to Radiant Logic's Virtual Directory Engine - the XML connectors, the "stored triggers" of SQL for the non-XML-enabled databases, the relational back end for robust storage with an adaptable front end for ease of use. Michel Prompt and his team at Radiant Logic are much farther ahead, but they've also been at it longer than the folks at Coherity.

I never did get to talk to Ken Tsai very much - we skipped a lot of the marketing dialog. But I did learn that most folks in our industry spend too much time in their own tight little world. Ellsworth in Palo Alto and Michel Prompt in Novato are less than 50 miles away from each other. Each invented a similar system, for different reasons and with different tools, but with almost identical outcomes. Yet neither knew of the other's work.

We need to change that. We need to see what the other guy is doing. Not the other guy working on a directory, but the other guy working in an entirely different field. Maybe, just maybe, he can help us solve the problem we're facing.