Open Source Love Day March 2010

Our Open Source Love Day for March 2010 brought love for Grails, our cmake hudson plugin, RXTX and winp. Everything went smooth and was lots of fun.

Yesterday, we held our first Open Source Love Day (OSLD) for this year. The last OSLD was at December 2009. Then, we reassigned a day in January and February each to perform our relocation to the new (and much bigger) office. But now we are back to regular duty and had the time to donate some work back to the Open Source ecosystem.

The Open Source Love Day

We introduced a monthly Open Source Love Day to show our appreciation to the Open Source software ecosystem and to donate back. We heavily rely on Open Source software for our projects. We would be honored if you find our contributions useful. Check out our first OSLD blog posting for details on the event itself.

Participate at our OSLD by using the features we’ve built today:

  • Grails still has some bugs. Instead of only complaining about them, we try to fix them. There is a bug with checkboxes and nested boolean properties that bugged us in a customer project. It’s filed unter GRAILS-3299 and has a proposed patch now.
  • In previous OSLDs, we produced the cmake hudson plugin. In the corresponding blog entry, comments with bug reports began to pile up. They addressed issues with hudson master/slave setups. So we implemented a hudson master/slave test environment, using VirtualBox virtual machines to perform as slaves. This setup quickly revealed the problems that were typical enough to devote a complete blog entry about this topic soon. Fixing the problems resulted in the new cmake hudson plugin version 1.2 to be released yesterday.
  • We are using the RXTX project to perform serial (RS232) communication in several projects. We are really glad the project exists, because the “official” communications API from Sun/Oracle is nothing but a mess. With RXTX, we only had a problem with emulated COM ports. Emulated COM ports exist when you use a USB->Serial or Ethernet->Serial converter, which is what our customer chose to do. If you unplug the converter during operation, the corresponding COM port disappears. This causes RXTX to crash, bringing the JVM down, too. We wrote a test application and used it with every converter we own (and we own quite a lot of them!). Then we began tracing the RXTX source code (at C code level), altering it to “only” throw an IOException when the virtual COM port disappears. The corresponding patch will be proposed to the RXTX project soon.
  • Another API we use a lot is the tiny winp project, written by Kohsuke Kawaguchi, the creator of hudson. We kill Windows processes with it, within a project that runs on Windows 2000, Windows XP and Windows 7. The latest Windows version seemed incompatible with winp, even the 32bit edition. We didn’t find the cause for this, but developed a workaround that will be proposed to the winp project soon.

What were our lessons learnt today?

  • If you face OutOfMemoryErrors on a 64bit Java6 JVM, try to switch back to a 32bit Java5 JVM. It helped us with our Grails bugfixing (during the test phase).
  • Hudson Master/Slave support for plugins isn’t particularly hard. It’s just that you need to be aware of the topic and replace some types like We gathered the same experience twice with our Crap4J plugin and the cmake plugin. It’s time to tell the world about it. Stay tuned!
  • The good old error return code is an error prone coding paradigm, because all too often, users of a function/method just forget to check the returned result. This was the case with a call to WaitForSingleObject in RXTX.
  • If you don’t understand an implementation well enough to fix the cause, you might at least be able to produce a workaround. It’ll work for you and provide guidance for the original author about where the bug might hide. This is why we count our winp efforts as success, too.
  • Your project either is mavenized or it isn’t. Everything in between is half-assed.

This OSLD was a bit short, as we had some guests in the evening, but nevertheless, it was fun. Well, to be precise, it was this special software engineer’s type of fun: The whole company was remarkably quiet most of the day, with everyone working totally focussed. We scratched our own itches, enhanced our customer projects and contributed to the open source community. A very good day!

Stay tuned if you want to know more about the specifics of the hudson plugin development or the to-be-proposed patches. We will publish them here.