Q&A: OMG member talks up UML 2.0

Bran Selic of IBM and OMG touts first major revision of model-driven development standard

InfoWorld: What are you hearing from the developer community at large about UML 2.0 and how it’s benefiting them or how they may be having a problem with it, if there are any problems?

Selic: Well, as you can imagine it’s of course across the board. There are people who are repeating some criticisms which in my view are not justified, but in general there’s a lot of interest. I just did a tour, I was in Korea for example last week, I was in Brazil the week before that. Four weeks before that I was in Europe, and I can certainly tell you there’s a tremendous amount of interest in this and this is why I expect that model-driven development will actually [grow]. The adoption of that will accelerate.

But one of the criticisms that you hear, I think the two most common criticisms that I hear, are, one, that it’s too big, and two, that it’s got no semantics, that it’s mainly notation.  Anybody who has actually looked at the standards would not claim that. The language is somewhat extensive but it is organized modularly so that, in fact, you don’t actually have to learn the whole language in order to use it. You can learn a very small part of it to be effective with it. And then you can add on bits, or if you like, modules of it as need be. Just like you don’t have to know all of English to be effective, the same thing is true in UML. And this is something we did in UML 2.0.

InfoWorld: You’re calling it a language.  You still can use it with more common programming languages like C+ or C or Java, right?

Selic: Yes, you can. And a lot of people do that, I’d say a significant percentage of UML users are essentially using it to model traditional, typically object-oriented programming languages, but also in some cases legacy languages such as Cobol and so on. Those are being modeled. But yes, you can do that.

But languages such as Cobol, for example, don’t have a concept such as a state machine, right? That’s something that in some domains is a first order notion and yet if you’re working with a language such as C or C#, you’re going to have to build that in.

InfoWorld: So UML has a state machine?

Selic: Yes, it has state machine. [In addition], what we added a lot in 2.0 is of course our software architecture descriptions, and here we basically took the queue from architectural description languages. We have some of the experts from Carnegie Mellon involved in the definition of that. The whole idea is to be able to model large-scale systems because that’s where you need modeling most.

InfoWorld: On large-scale systems such as what?

Selic: For example, I know of systems such as, say, large telecom systems which tend to be very complex systems consisting of tens of millions of lines of code.

InfoWorld: What about, say, an enterprise banking application or something like that?

Selic: Oh sure, those actually don’t tend to be as large individually, although they tend to be networked. And yes, you can model those things now quite accurately.

InfoWorld: Can you describe what you mean by state machine and software architecture descriptions?