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Integration Exercise: Java Library Wrapper

written by Shane Emmons for Mendicant University core skills session #9

The world is full of Java. Chances are pretty good if you walk into a corporate IT department you'll find Java. So, what do we as Ruby developers do when forced to work with Java? We turn to JRuby and it's Java integration. Your assignment, should you choose to accept it, is to use JRuby to wrap an existing Java library into a new Ruby gem. You can choose any Java library you like. However, if there already existing a functional and active gem, you should look at wrapping a different library unless you plan on taking a different route. Either way, please have Greg or Shane approve your chosen library before starting work in earnest.

Oh, and one more thing. We don't just want this to be a straight API copy of the existing library. Abstract things away from the programmer so that working with your gem is easier than working directly with the library via JRuby. The code below is an example of what not to do.

session   = CrystalEnterprise.getSessionManager.logon(user, password, cms, authtype)
infostore = session.getService('', 'InfoStore')

With a little bit of effort, this interaction could be made to feel a lot more natural to a native Rubyist. The code shown below is much closer to what you should be aiming for.

session   = Enterprise.connect(user: "shane", password: "password")
infostore = session.infostore

For a more complete example, see Shane's bosdk wrapper.

Exercise Summary

  • You should create a gem using JRuby that wraps an existing Java library.
  • Your gem should work with a Java library that doesn't already have a good wrapper.
  • You should make the API for your library look and feel like Ruby, not Java.

Submission Guidelines

If you plan to work on this exercise, you should fork this repository and push code early and often during the course. The course guidelines PDF explains the submission process in detail, but please contact an instructor if you have any questions.

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