I anounced in the previous post that I am looking for contributors to my open source projects.

I described the big picture, how I expect us to be working together but still, more details are needed. That’s why I wrote this post. It will cover three topics: communication, tasks size and some guidelines regarding coding style.


It is important to note that 99% of our chatting should take place inside Github issues. No meetings, skype calls or long email threads - I consider them (and I think most people agree) a waste of time. Besides, it’s easier and more practical to have all the information related to a ticket inside the ticket itself.

Size of tasks and workload

In the previous post I also mentioned PDD. This concept will stand at the core of our collaboration, because it allows for small tasks (30min to 1h estimation) that should find their place easily in most people’s schedule. I expect a contributor to spend under 6h/week writing code for these projects.

As you can read in the article, PDD has a number of advantages that you should keep in mind:

  • Small tasks: don’t spend more than 30m to 1h on something. Puzzle stuff out, create other tasks.
  • Small pull requests: don’t make a PR with 15 changed files. I would say if you narrowed-down your task well enough, your PR shouldn’t contain more than 5 changed files (5 changed files already means a big task, from my point of view). This also makes the life of the code reviewer easier!
  • Tracking down of changes and bugs becomes much easier
  • Bugs are reduced since everyone is working on small and clear topics

Code style and rules

The projects use checkstyle to control code quality. The build will fail if any of the style rules is violated. You will see it in action, but here are some firsthand tips:

  • No TABs (this is mostly for readability and navigation) - for instance, lines containing tabs are poorly aligned in the Github view.
  • 4-space indentation.
  • Lines should contain maximum 80 characters.
  • Classes are either final or abstract.
  • Local variables and parameters should be final
  • Avoid null at all costs. Do not ever return null! The first argument to this is that no one wants their users’ code to be polluted with checks for null or create NPEs out of nowhere.
  • Avoid get/set prefixes in method names. Read this. Of course, we will never choose that over the power of JAXB for instance, but in most cases we will not need to use such frameworks.

Also, keep in mind that the master branch is read-only. You should solve the ticket you are assigned on a separate branch named after the ticket number (e.g. ticket number 123 should be solved on a branch named 123).

Every PR will be reviewed by a code reviewer and you will probably be asked to make adjustments to your solution. At first, it will be only me, but in time, if we manage to build a solid team, others will have this role as well.

Sounds interesting? Got any questions? Just ask, I’ll be happy to answer.