Steven Kelly on DSM

Once again, Code Generation proved itself as the best European conference on Model-Driven Development. Lots of smart people, lots of experience, lots of enthusiasm, lots of willingness to listen and learn from others. Even though having to prepare and run some sessions hampered me from seeing as much of the rest as I'd like, there's still too much to write for one blog post. I'll post about things I'm certain of first, and come back to things like Xtext and MPS after further investigation.

Keynotes

The two keynotes, both presented as a double act by me and Markus Völter, seemed to go down well. Mark Dalgarno had a surprise up his sleeve, presenting us with a blind choice of weapons from a black bag. We then had to duel it out, graphical DSM against textual DSLs, with the plastic gun and dagger we picked. Since I got the gun, I think the result was a foregone conclusion :-). The dagger may be a "weapon from an earlier, more civilized age", but it's only useful if you can get in close to your adversary. Similarly, text may be more familiar, but it does often tie you closer to the code; problem domain DSLs in text seem as rare as accurate knife throwers. Markus successfully stabbed me in the back later on, so that evened things up and emphasized the point from our slides: both text and graphics are useful in the right place. Choose, but choose wisely.

It was fun to see the keynote get picked up on Twitter:

EelcoVisser: keynote by @markusvoelter and Steven Kelly at #cg2009: great overview of issues in model-driven development

HBehrens: Steven Kelly at #cg2009 keynote: "wizard based generators create a large legacy application you've never seen before"

The latter was picked up by several people. The reference was to vendor-supplied wizards, often found in IDEs or SDKs, that create skeleton applications for you based on your input. Since the vendors take pride in just how much boilerplate they can spew out, you're left with a mass of generated code that you've never seen before, but must extend with your own code. Worse, you're responsible for maintaining the whole ensuing mixture, and there's no chance of re-running the wizard to change some of the choices -- at least not without losing or invalidating the code you've added. That's in sharp contrast with generation in DSM, where your input is in the form of a model which you can edit at any time. You get the speed of generation but can remain at a high level of abstraction throughout.

MetaEdit+ Hands-on

We'd decided to try something special in the hands-on: building 5 different graphical modeling languages from scratch in under 3 hours. Rather than being random exercises, the languages were increasingly good ways of modeling the same domain. We started with something that was basically just the current code turned into graphics, and ended up with a language that reduced the modeling work to a third of what it was at its worst, with many possible errors ruled out by the language design and rules, and with much better scope for reuse. We showed how to make generators for all the languages, and actually built them for two. And of course since this was MetaEdit+, simply defining the metamodel already gave you a full graphical modeling environment -- we just tweaked the symbols to taste.

Never having run the session before, we were rather nervous about how much we could achieve in the time available. In the end, thanks to great slides from Risto Pohjonen and testing from Janne Luoma, it seems we pretty much hit our target. Only at the very end of the last language did we have some people only just starting the last section (the generator) while others were finishing it and going on to beautify the symbols or play around with other fun features of MetaEdit+. Hopefully people learned not just about MetaEdit+ as a tool, but also how to make better languages and improve existing ones. Feedback online was encouraging:

PeterBell: Great metaedit hands on - built and refactored language and generator in just a couple of hours at #cg2009

elsvene: been to a great hands-on session for MetaEdit+. Really interesting tool! #cg2009

HBehrens: for me MetaEdit is the most sophisticated graphical modeling tool currently available #cg2009. Thanks for this session!

Dinner

The conference dinner was of the high standard you'd expect from a Cambridge college. The airy hall and contemporary art lent a friendly ambience. The large round tables weren't particularly conducive to conversation: you could only really talk to the people either side of you without shouting or craning your neck. On long tables you can reach 5 people for the same effort. I was fortunate to be sitting between Scott Finnie and Jon Hurwitz, so I certainly didn't suffer.

The "suffering" started later, when there was a raffle in aid of Bletchley Park, the home of Allied code-breaking work in World War II. I ended up winning a prize donated by Microsoft: a screwdriver toolkit and MSDN T-shirt, causing much hilarity and bad jokes about finally getting Microsoft tools that didn't crash. The irony continued when Alan Cameron Wills won a signed copy of our Domain-Specific Modeling book -- despite having received one from us last year. Either the older British segment of the audience were most inclined to support Bletchley Park by buying raffle tickets, or then the draw was rigged to encourage vendor co-operation. The people on my table were having none of that, and encouraged me to cover up the Microsoft logos :-). All in all a good laugh, and in a good cause.