Thursday, 7 October 2010

Scala Lift Off - Day 1

I've been at Scala Lift Off London today (#scalalol). Had a great time and attended talks by some really knowledgable people. Also met some people doing some really great suff with Scala. The 'unconference' format took some getting used to at the start, but the group created a great agenda and it all came together nicely. Here's my take on today's talks and some ideas that I might propose for tomorrow.

Session 1 - Moving from Java to Scala
An interesting discussion of how a company moved from building apps in Java to their first Scala deployment. An interesting study on how you can move along incrementally, bringing the whole team along as you go. Their progress can be roughly described as:

  1. Start writing unit tests for Java code in Scala
  2. Use Scala for main code, but still using Java coding styles (i.e. Java without the semi-colons, getters/setters and boilerplate)
  3. Starting to make use of Scala features to improve code (e.g. Option instead of null)
  4. Using more of the Scala language features (e.g. closures, immutable types etc.)
  5. Adopt the additional functional aspects of the language (e.g. map/flatMap)

What I thought was very interesting of their approach of not moving on to the next level of Scala until all of the team were up to speed with the current level. Also, their approach of getting the whole team on board in terms of style was excellent.

This certainly proves it is possible to move a team of Java programmers to the Scala language. I'd certainly love the opportunity to take one of the teams that I work with on this journey on a project over the space of 6-9 months.

Session 2 - Akka
A fantastic session with Jonas Boner (@jboner) presenting the main elements of the Akka framework. The actors model for building scalable concurrent applications really excites me. I can see many cases where things that I'm working on now could be made much simpler, but at the same time more scalable and performant by adopting this model.

I can certainly see some major architectural changes in the future for building large systems. Applications composed of thousands of lightweight actors, all working concurrently and passing messages around has got to be better than the current model of a single thread handling a single request and trying to deal with all the synchronisation issues whenever shared state is involved.

Also very impressed with the supervisor model within Akka, where a supervising actor can manage a number of other actors and control how they get restarted in failure cases and so forth. Also, the distributed actor model looks great and is almost seamless (although deployment might be more challenging!)

I'm certainly looking forward to building some actor based applications. I'll post details as I do.

Session 3 - Experience of using Scala and Akka
Although this was an excellent session, it was probably the least valuable one of my day. It was great to hear about a successful project that used Scala and the Akka framework - especially how quickly and easily it all came together. However, not much new information.

Session 4 - Software Transactional Memory (STM)
Another great session with Jonas Boner, looking at the STM support within Akka. I've played a bit with STM in the past, but combining this with the actor model looks very powerful. It's all very new at the moment, but I can see some great applications for this approach. The session also turned into a great discussion of STM and I learnt a lot of good stuff.

Other Thoughts
Martin Odersky (@odersky) did what looked like a great talk on advanced Scala and implicit conversions. Sadly I missed this as I was in the STM session. Looking forward to watching the video on this one.

Today for me was definitely an Akka day. However, a lot of the other sessions seemed to be on quite advanced or specialised topics. I'm hoping tomorrow to focus more on Scala and Lift, with perhaps some more intermediate and generic sessions. Some suggestions I might propose:

  • WTF is a Monad (and other Functional Goodness): I'm coming from a Java background and while I get the functional approach in Scala I still find it fairly challenging to work with. Some real world examples would help
  • The Scala Type System
  • Building Lift Applications for developers familiar with Java frameworks (e.g. Wicket, Tapestry, JSP, JSF)

Looking forward to tomorrow.

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