Getting used to gradle, a case study : developing Qi4j

Lately Qi4j moved from maven to gradle:

Qi4j community migrated away from Maven after several years of frustration, especially around release management, versioning and cross-module dependency resolution issues, in Feb 2011. The tool of choice is now Gradle.

What ?

The case study I want to describe today is quite simple. I’m writing an application using Qi4j, it’s build is maven based. As I am contributing to Qi4j alongside the development of my own application I’m using the development branch of Qi4j most of the time. In maven terms it means my application depends on the last version SNAPSHOT. I want to continue working this way so I’ll describe here how to use the Qi4j build system for this use case.

In other words, you’ll learn how to manage the Qi4j build system for developing Qi4j and use it in maven projects.

What not ?

I will not talk about IDE support here, only build systems, namely maven and gradle.

Making it work

The main goal is to find gradle commands for different aims and make their run as short as possible.

I used the same computer for all time mesures present in this post, a Samsung netbook N150 with 2GB RAM and a Vetrex II solid state drive from OCZ.

Commands described here last from 45 minutes to 5 minutes for building and installing the whole Qi4j ecosystem in the local maven repository. When dealing with single modules all this gets very quick. For example org.qi4j.core.api can run in 20 seconds when skipping tests and javadoc.

Here are some example gradle commands. I use the gradle daemon to get rid of the startup time.

$ gradle install -Dversion=1.3.0-SNAPSHOT

This one takes forever, it will buid and install locally all artifacts (main, -sources, -javadoc),run tests and then generate the qi4j-sdk distribution archives. Took my netbook ~40 minutes.

$ gradle -x test -x javadoc -x javadocJar -x sourceJar -x :javadocs -x :distLayout -x :tarBinaries -x :tarSources -x :zipBinaries -x :zipSources install -Dversion=1.3.0-SNAPSHOT

This one build and locally install all main artifacts skipping tests, javadocs, sources and distribution archives. Took ~5 minutes on my netbook.

$ gradle -a -x test -x javadoc -x javadocJar -x sourceJar -x :javadocs -x :distLayout -x :tarBinaries -x :tarSources -x :zipBinaries -x :zipSources :org.qi4j.libraries:org.qi4j.library.servlet install -Dversion=1.3.0-SNAPSHOT

This one build and install only the org.qi4j.library.servlet artifact, skipping tests, javadocs and sources archives and ignoring changes in other modules. Took ~15 seconds, now that gets usable !

Theses are quite hairy, aren’t they?

Getting easy

To ease my work I wrote some shell scripts around gradle. They are available on github here: https://github.com/eskatos/qi4j-dev-scripts

Here is the help of the qi4j-build command:

paul@petit:~/src/github/qi4j-sdk$ qi4j-build 
qi4j-build [-p group:project] command [flags]

  -p Select the target project
    group can be core, library, extension, tool, sample or tutorial
    project is the base name of the targeted submodule

  Available commands
    clean            Clean output
    test             Run tests
    install          Install only main artifacts
    devinstall       Install javadoc and sources artifacts
    distinstall      Install distributions archives

  Available flags
    skipTests        Skip tests

  Examples
    qi4j-build clean
    qi4j-build devinstall
    qi4j-build library:servlet test
    qi4j-build libraries install
    qi4j-build distinstall

Feel free to report issues, fork and request pull.