Exploiting JRuby: Building Domain-Specific Languages for the Java Virtual Machine
TS-9294

With the increased interest in dynamic languages such as Ruby and Groovy, many developers are left wondering how best to utilize the features in these languages without losing out on the power of the Java platform. Perhaps, the most beneficial way to start with dynamic languages in Java technology is to focus on building Domain-Specific Languages, that build on existing infrastructure reducing risk but increasing productivity.

This session presents an in-depth tutorial on domain-specific languages, the motivations for them, how to build them, and where to steer clear. Starting with a discussion of the different kinds of DSLs and where they fit in typical enterprise organizations, the presentation gives you a clear roadmap of how you can start to exploit the power of dynamic languages.

The bulk of this session focuses on the main metaprogramming techniques needed to build a successful dynamic language:

• Operator overloading
• Duck typing
• Symbols, hashes, and blocks
• Method missing
• Dynamic type extension

Accompanying the discussion of each of these techniques is an in-depth analysis of a variety of different DSLs you can use as starting points for your own work.

Rake, the Ruby make tool, is an excellent example of building a general-purpose DSL and of typical DSL techniques. In this session, you see a full breakdown of the Rake syntax and learn how the Rake build files map to the basic DSL techniques.

MScript, a DSL created by the presenter for accessing and manipulating objects exposed with Java Management Extensions (JMX), is a poster-child example of the flexibility of combining Ruby syntax with the power of the Java platform, using JRuby. You see a step-by-step breakdown of the MScript syntax, again with mapping back to the basic set of techniques.

CAScript, a business-area-specific DSL for defining entitlement rules for corporate actions, illustrates the use of DSLs in a vertical market: investment banking, in this case. The basics of corporate actions are easy to grasp for anyone who is not already familiar with them, and you find out how DSLs can provide power mapping between concepts in the business domain and in the code.

The attendees should have a thorough grasp of the Java platform, and familiarity with Ruby syntax would be beneficial.

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