Transactions on Android

Every year I try to make time for pet projects, be they learning new languages such as Erlang (one of my 2007 efforts), writing a discrete event simulation package in C++, or one of my best which was writing the world's first pure Java transaction service over Christmas 1996. Most of the time I don't manage to make much progress throughout the year, leaving the bulk of the effort for over the Christmas break.

This year was no different, with "port Arjuna (aka JBossTS) to Android" on my to-do list for months. I've been playing around with Android for quite a while, even collaborating with some friends on writing a game (iPhone too). I know that although it's Java-based, there are enough differences to make porting certain Java applications tricky. But over the years I have found porting transactions to different languages and environments a pretty good way to learn about the language or environment in question.

So as well as doing my usual catch-up on reading material, breaking the back of the Android port was top of my list. Now in the past I'd have higher expectations of what I could accomplish in this time period, but these days I have a family and some things take priority (well, most of the time). But once everyone had opened their presents, let the turkey settle in the stomach and sat down to watch The Great Escape (hey, it's Christmas!) I found time to kick it off.

I started simple in order to remove as many variables from the problem as possible. So I went back to JavaArjuna, the ancestor of JBossTS and all that predated it. It has none of the enhancements that we've added over the years, but places less requirements on the infrastructure. For instance, it was JavaArjuna that I ported to the HP Jornada back in 2001 because it also worked with earlier versions of Java.

As in 2001 it went well and it wasn't long before I had transactions running on my Android device. It was nice to see one of the basic tests running and displaying the typical transaction UIDs, statuses, rolling back, committing, suspending etc. Then I moved on to JBossTS. It wasn't quite as straightforward and there are a few hacks or workarounds in there while I figure out the best way to fix things, but it's done too! I'm pretty pleased by the results and will spend whatever time I have in the coming weeks to address the open issues. And I've definitely learned a lot more about Android.

So overall I think it's been a good pet project for 2011. It also showed me yet again that the architecture and code behind JBossTS that the team's been working on for years is still a highly portable solution. It doesn't matter whether you want transactions on a mainframe, in the cloud, or on a constrained device, JBossTS can do them all!