Yesterday evening I attended a session on domain-driven design (ddd) at Sogyo‘s offices, a nicely converted farmhouse located somewhere in the center of Holland. I was amazed to hear Ruby and Rails being used as an example of domain-driven development. One of the presenters even claimed that Dutch Rubyists Remco and Michiel (who reached 2nd place at this year’s RAD Race, a programming contest) had done so well because they were able to work domain-driven, thanks to Rails.

Surely he was joking. If there is one data-centric framework out there at the moment, it has to be (my beloved) Ruby on Rails. Let’s see…

• Rails’ “domain” classes (the model) are literally an implementation of the Active Record pattern, which has a direct coupling to corresponding database tables.
• As a result, Rails’ model classes correspond directly to database tables; a change in your table (e.g. an extra field) is automatically a change in your model class.
• Worst of all, DHH is actually on a mission to model the whole world under the constraints of CRUD.

I really don’t see how you can call this domain-driven. This is not to say that you couldn’t implement a domain model (as in ddd) in Ruby. But in my opinion, that is not what Rails is about. Rails is limited to the presentation layer, so its model is nothing more than a view model. For small scale applications that’s good enough. But if you need your business logic to be available independantly, to be accessible from multiple views (presentation layer applications), you’ll want to put that business logic in a separate layer, not in the model of one of those views. That is how I see “enterprise Rails”: as a tool to rapidly develop presentation side applications that use and combine existing business services (WS, EJB) (using JRuby on a Java application server).

The question remains if a domain model could be implemented in Ruby (not Rails). Technically, you could, of course. But would I want to? I’m not sure. It’s very reassuring to have the Java compiler checking your back and Eclipse’s refactoring tools at your disposal. You’d have to have some very tight unit testing to replace those and still feel safe about any changes you make. I mean, we’re potentially talking about a large company’s vital business rules here. Would I feel comfortable duck-typing those? On the other hand, there’s Ruby’s excellent DSL capabilities that would come in very handy for specifying exactly those business rules. What do you think?

So much to do in this hot and cold summer (July: 36 degrees, August: 16 degrees) and so little to blog about. In case anybody wonders, this is what I’ve been up to lately.

Gone back two years in time: After I finally left the WebLogic project in May, a little later than planned, I was re-assigned to the organization I worked at two years ago. It was as if time had stood still when I got back there. Not only because there were many familiar faces to welcome me, but also because the entire development environment was pretty much as I’d left it. So it’s back to Java 1.4, back to Struts, back to EJB’s, back to this pre-SOA SOA architecture… Then again, as someone asked me: what would I use instead of Struts? What indeed, if not Ruby and Rails? Does it really matter which XML-infested Java framework you use? Would Shale or Spring MVC make so much of a difference? I get by because there’s a lot of code and XML to copy/paste from, but the amount of code that is the result is frightening.

Trying to keep up with the insane tempo of the JRuby guys: After trying to get Rails on JRuby to work for my NLJUG presentation in May, with help from Charles Nutter and Tom Enebo, the JRuby protagonists, I kind of stuck around on the JRuby mailing list, which reads like a Dan Brown novel (well it does if you like coding). I even got a small job, rewriting Mongrel’s HTTP/1.1 Ragel parser to a JavaCC grammar (Why is there no Ragel-to-Java translator? I wish I’d had the time to write one. Now I had to use JavaCC, which was rather frustrating, either because of the limitations of JavaCC, especially in its idea of regular expressions, or because of my own limited knowledge of parsing–but it’s here, checked in in a fresh new RubyForge project, ) and it seems to be working. Mongrel will work completely with JRuby if Ola gets his JRuby extension framework going, allowing you to extend the Ruby language with Java libraries as easily as you can now with C libraries.

Organizing the Java Summer Camp 2006: After last year’s success with Simon Ritter‘s presentation of Java 5’s new features (fortunately no-one seems to remember the train mixup that got Simon 50km away from the venue and cause Rietje (office Mom) and me to pick him up there and drive back at questionable speed), Profict decided to do another Java Summer Camp this year. Like RubyEnRails before, this turns out to be very time-consuming. Finding a theme (Java & Ajax), speakers (Greg Murray! Bram Smeets!), visitors (90+, we’re fully booked!), a venue (another castle!), seats, food, sound system, camera, parking space…

Got my first production-worthy Rails application live: as a side note to the Java Summer Camp, I rewrote the small Rails app that I used to keep track of the RubyEnRails visitors. It can now handle multiple events, multiple users, it sends bulk email to visitors, it exports visitor data to Excel to keep the managers happy and it has a new and improved gui (which took me longer to design then it did to code the application itself).

Busy finding new colleagues: Yes I know, I should be proclaiming the wonders of Ruby and Rails at all times–but the truth is, I don’t hate Java, I don’t mind (that much) doing Java as a day job, and I don’t mind working for a Java shop. Although I’ll never quit dreaming of my own world empire, someday, somehow–in the meantime I’m very happy to be working for Profict. In spite of its focus on doing application integration projects (some people love diving in at the deep end, writing code that never sees the light of day; but I prefer staying near the surface, where the code reaches the user’s screens); but there’s enough work to do at the edges of integration: portals for one; and there are always the external assignments that I’ve been on for the last couple of years (what’s English for detacheren??). But what I really like about Profict is the fact that it’s small enough to know everybody (no huge consulting firm for me, thank you). It is a close group of mostly very experienced people, formed over the years only ‘by invitation’ (employers asking those people around them to join that they themselves would like to have as colleagues). So maybe I shouldn’t advertise the fact that we’re looking for still more people on my blog, for everyone to read–on the other hand, if you’re persistent enough to read this blog entry, you’re welcome to come talk (well, if you live in Holland anyway)! Okay, end of shameless commercial intermezzo…

Done a Grey’s Anatomy and The O.C. marathon: If you hate The O.C., you have got to at least love its theme song: California by Phantom Planet. That alone makes me want to go there (or at least as soon as flying to the US becomes a little more relaxed again). And Grey’s, what can I say: it’s little more than the 835th romance-in-a-hospital show (St. Elsewhere, Chicago Hope, ER, Medisch Centrum West) but there’s something that makes me want to keep watching–maybe Izzie? (A supporting character is usually my favorite: Summer in The O.C., Chloe in 24, Paris in Gilmore Girls, Starbuck in Battlestar and of course Locke in Lost; the exception is Prison Break).

Making the switch to Linux: Somewhere in the process of getting Subversion with SSH to work under Windows XP, which proved a hopeless case, either with or without Cygwin or VMWare, I decided to to finally make the switch. I shrinked my XP partition (I’ll still need it for graphics and photography work, as I just can’t get the Gimp to do what I want just as easily) and installed Ubuntu Dapper Drake. It feels like coming home (I worked with VMS and Unix long ago). It’s still not MacOS yet, but at least my 3GHz Dual Core cost just a third of Apple’s new beast…

Twice a year the Dutch Java User Group organizes a mini conference with sessions about Java, JEE, and everything related. In spring this day is called J-Spring (which has nothing to do with the Spring framework), in fall it’s called J-Fall. While preparing for RubyEnRails 2006 I thought it would be a good idea to enter a paper for the J-Spring, for an introductory session called Is Ruby The New Java?. I was a bit surprised when my paper was accepted, and even more surprised last Thursday (J-Spring day) about how many Java people showed an interest for my session: I got the big conference hall (and it really does look big when you climb the stage), filled with maybe some 200 people. Even though I got the usual nervous questions about things like duck typing and performance, I had the impression that overall, people really liked what they saw. Apparently Ruby and Rails are hot in Java land.

And likewise, Java is hot in Ruby and Rails land; allbeit with a slightly different angle. I’m talking about the JRuby project, an interface to Java allowing Ruby code to run under a Java Virtual Machine. JRuby’s ‘holy grail’ being to be able to run Rails applications in a Java application server. At this year’s JavaOne, JRuby lead developers Charles Nutter and Tom Enebo were able to show a working Rails application running under Tomcat. In spite of their help and a lot of emails, I did not manage to reproduce their setup for a demo at J-Spring. Instead, I showed how easy it is to call an EJB from Ruby, as well as a Rails application based not on a database but on a Java web service.

You might wonder what’s the use of such an interface to Java. Like I said in my J-Spring presentation, I believe it offers some great possibilities for the future of Ruby and Rails. Once Rails runs on the JVM, it becomes that much easier to use Rails within established enterprisey Java environments. For that to happen, Java developers working within those environments need to be convinced of Ruby and Rails’ added value. And so I hope that my presentation has helped to convert some of those Java developers to Java developers-who-want-to-develop-with-Rails.

If you’re interested you can download my presentation here.

It’s been almost two weeks since RubyEnRails 2006, the first big Dutch/Belgian Ruby and Rails event. I think it’s safe to say that it was a success. Over 100 visitors showed up; we had an excellent venue and six very entertaining sessions:

• Frank Oxener (Agile Dovadi) gave a live demo of building a Rails app and integrating with Google Maps.
• Geert Rozendom (Newminds) told about his company’s efforts to integrate Microsoft Navision with a Rails frontend (we got some frowns here from people disliking anything Microsoft; well, a lot of people use Microsoft software, so deal with it guys!).
• Michiel de Mare (Finalist) gave a Takahashi style introduction to object oriented programming with Ruby (up to and including continuations, a brave effort).
• Stefan Kaes told us everything there is to know about Rails performance. He did a two hour session packed with tips and tricks for measuring, tuning and refactoring.
• Wilco Bauwer is working on IronRuby, a Ruby compiler for .Net, similar to IronPython. There’s a lot of attention for RubyCLR, but not many people have picked up yet on Wilco’s project. He explained that the difference is that RubyCLR is building a bridge between native Ruby and the CLR, while IronRuby is a complete implementation of a Ruby interpreter in .Net (see for an explanation of the .Net lingo). Again some sour anti-Microsoft faces here, but they were all silenced in awe when Wilco got Ruby to play the Mission Impossible III trailer on the sides of a rotating cube.
• Erik Veenstra, finally, Holland’s uber Ruby guru, did a session on metaprogramming in Ruby. He showed how to implement your own attr_reader/attr_writer methods, and, one step beyond, the road to creating DSLs with Ruby.

All in all it was a great day, fun to organize and a pleasure to meet so many Ruby and Rails enthousiasts at once. We should do this more often! Next time, we should maybe have separate Ruby and Rails tracks (most people want to do either Ruby or Rails; a shame really). And even though Huis de Voorst was a splendid venue, a more central location would perhaps be easier for most attendants. And we should have more sessions, and more advanced sessions. And onsite wifi so people can blog while they’re there. And less xxxl-sized t-shirts (there’s still a few left!). And, and, and……

(The presentations can be downloaded from rubyenrails.nl, but they’re Dutch except Stefan’s. Photos on Flickr, tagged rubyenrails.)

For some mysterious reason, there seems to exist a correlation between the temperature outside and the amount of entries on my blog. A sudden and long-awaited spell of sunny weather has been making Holland happy for more than two weeks now. In the evenings I am faced with the choice between sitting outside for a little longer, glass of chilled wine in hand, waiting for the sun to set and the blackbirds to start singing — or sitting inside, behind the computer, working on my blog. What a tough choice.

It’s good to see the weather’s changing though, from downright hot to a temperature better suited for, let’s say, a conference. One week from now we’re hosting RubyEnRails 2006, the first major Dutch/Belgian Ruby and Rails event. Besides Dutch Ruby guru Erik Veenstra, some real-life Rails cases, and Wilco Bauwer presenting his Ruby-on-DotNet compiler, Stefan Kaes is doing a two-hour workshop on Rails performance. And then there’s the Rails introduction workshop Remco and I will do, coding a simple photo album application live to show how quick & easy it all is (that’s the plan, anyway!). Over 100 people have already registered. It may not be London, Chicago or Vancouver, but we do have the most historic venue of them all: a 17th century Dutch castle.