Friday, September 14, 2012

Boost your Groovy with NailGun

Are you working on a large Hibernate project that takes long time to load up all the hbm.xml files when creating the Session object? This is fine during deployment and runtime because it only loads it once. However, often time we also need to the same Session object to do some ad-hoc HQL queries to debug or validate data. Loading and re-loading large mapping files in a Session to just execute single query is very painful.

Now, I like to poke around Java things with Groovy, and it's a great tool to peek at your data as ad-hoc queries as well. You can easily do this with their groovyConsole GUI tool and add --classpath option to include your project classes. This will bring up a tiny Editor, and you can script to load your hibernate Session there. Once the first run is loaded (the hibenrate Session created), then second run is almost in an instant.

Running the little groovyConsole had wet my appetite, and I was hungry for a better text editor, but yet I don't really want a full blow IDE for scripting. I like do my scripting in a plain editor. Now if you have an editor such as Sublime Text 2 (ST2) that has a "build" feature to execute a external command, then you will enjoy scripting much more. With ST2, I can have it call groovy.bat from inside the editor on the script that I am editing. However, there is another problem: the external command will restart a new JVM process on each run! Now I am back to square one.

To solve this problem, and still have my cake (editor), I recalled an awesome tool called NailGun. This works perfectly with Groovy and my problem. I can start a server like this

java -cp "groovy-all-2.0.1.jar:nailgun-0.7.1.jar" -server com.martiansoftware.nailgun.NGServer

And then in my ST2 editor, I can run an external command like this as the NailGun client:

/path/to/nailgun-0.7.1/ng groovy.ui.GroovyMain test.groovy

Nail gun client sends the script file content to the server and prints the result. Again, after first run, the second run should be instantaneously.

There, I scratched my itch.

Details on how to setup Sublime Text 2 to run NailGun client

  1. Go to menu: "Preference > Browse Packages"
  2. Open the Groovy folder
  3. Save a file named "GroovyNailGunClient.sublime-build" with the following:
         "cmd": ["/path/to/nailgun-0.7.1/ng", "groovy.ui.GroovyMain", "$file"],
         "file_regex": "^(...?):([0-9]):?([0-9]*)",
         "selector": "source.groovy"
  4. Select menu "Tool > Build System > GroovyNailGunClient"
  5. Press CTRL+B to run any groovy file in your editor.


  1. Can you clarify #2 "Open the Groovy folder"? The sdk folder? The bin folder?

  2. Hi,

    After step 1, the ST2 should automatically open up a folder for you, and in it there should be a Groovy sub folder. That's what I mean in step 2. Eg, in Mac, the full path is "Users/zemian/Library/Application\ Support/Sublime\ Text\ 2/Packages/Groovy"

    This is the folder where ST2 store all their commands and other language specific data.

  3. Any info on installing with ST3?