JMRI: Technical Info

You don't need to work with your own copy of the JMRI source code, compilers, etc if you just want to run the programs. You can download completely built copies via the downloads page. But if you'd like to play with the code, or get a copy of the program that contains updates since the last downloadable version was published, this section of the web site will help you get started.

JMRI project information (For people interested in how the software is being written)

Links to the SourceForge pages:

Project page

Statistics, Bugs, Feature Requests, Patches,

Browse CVS

SourceForge Site Status

JMRI-Developers mailing list: Subscribe, Archive

Code

All of the JMRI code is available from CVS. See the "Getting the code via CVS" and "CVS FAQ" pages for more information on how to do that.

Building Your Own Copy

In addition to getting a copy of the JMRI source code and reading it, you can also compile your own version of the program to run. You can even include your own modifications if you'd like.

There several different ways to do this. If you're already familiar with one of the popular "Integrated Development Environments" (IDEs), look at the navigation bar to the left for instructions on how to build JMRI using NetBeans, XCode, Eclipse or JBuilder.

NetBeans provides a very convenient system for building, running, and if need be debugging the program. If you're not familiar with some other method, we recommend trying NetBeans first.

Alternately, if you'd like to edit code with your favorite text editor and compile it from a command line, please see the page of instructions for building with Ant.

Contributing

We encourage contributions of code, decoder definitions, improvements to web pages, etc, to the JMRI project so that we can distribute them to the rest of the community.

For your first small contributions, e.g. a new decoder file or small bug fix, please fill out a new "Patches" entry on SourceForge using our patches page (click new on the middle-left, then fill out the resulting form). You can attach the entire file there. If it's multiple files, and you're using an IDE like NetBeans, it's very easy to create a "diff patch file" to carry your changes, and that will save us a significant amount of work merging them in. Please see the instructions for creating a patch file with NetBeans.

It saves us a lot of work if, before you create and send the patch file, you make sure that your copy of the code is up to date, and that the unit tests all work.

If you are doing a significant amount of development, please contact us so the we can make it possible to directly commit your changes into our CVS repository.

When you contribute your code to JMRI for the first time, we'll ask you to sign an assignment form that allows us to register copyright on the code, and gives us unlimited-duration license to redistribute it consistent with the JMRI licensing. (We regret this paperwork, but Matt Katzer's misuse of copyright makes it necessary). If other people also helped with the contribution, please let us know so we can add them to the acknowledgements page.

Licensing

We encourage people to build their own projects on top of JMRI. That's the original reason that the project was started!

JMRI is licensed only under the "GNU General Public License", sometimes called the "GPL". We use version 2 of the license, along with the "classpath exception" allowing people to link JMRI with their own code under more relaxed conditions. Copies of the license are distributed with the source and executable downloads, and can be gotten from the web.

This is both an "open source" and a "free" license. For more information on those definitions, please see the Open Source Initiative web pages, including their description of what Open Source means, and the Free Software Foundation web pages, particularly their licensing page.

Informally, the license means that there are only a few limitations on what you can do with JMRI. (Check the exact wording in the license for the details behind the following summary):

You can redistribute it, for free or for a charge to cover your costs.
You can build additional programs on top of all or part of JMRI, and distribute JMRI with them. This is OK whether or not you charge for your program.
You can modify the JMRI code for your own purposes.
You can distribute that modified code, though in that case you either have to make your modifications available to us, or also distribute an unmodified version at the same time.
You cannot use part or all of JMRI in another project without either giving credit to JMRI, or making special arrangements with us.
This includes decoder definition files: You are welcome to use them, including reformatting their content to another form, but you must give JMRI credit for their content.

If you have any questions about this, please contact us directly.