4 posts tagged with "JVM"

Introduction​

Java applications often choose to use an embedded scripting language for reasons including the following:

• to provide a powerful customisation mechanism for users
• to be able to change runtime behaviour without rebuilding/redeploying the application
• for providing business rules/logic
• per-tenant configuration for multi-tenant applications
• rapid prototyping for new features

When selecting a JVM scripting language there are many options to choose from including Jactl, Groovy, Jython (Python), JRuby (Ruby), JavaScript, and Lua. Out of these, Groovy is probably the most widely used scripting language for Java applications. This article compares Jactl and Groovy in order to show their strengths and weaknesses and when you might choose to use one over the other.

Jactl 1.3.0 introduces the ability to checkpoint the current execution state of a script and have it restored and resumed elsewhere after a failure. In order to test this new feature, I implemented a proof-of-concept project that simulates a payment processing system that accepts payment requests, performs some operations by interacting with multiple external systems and then returns a response.

I am often asked what the point is in having yet another language for the JVM. Apart from the fun of writing a compiler and being able to run actual programs using my own language, I wanted a language where the execution state could be captured and persisted such that if the server where the application is running fails, the execution state can be restored and resumed on another machine.

Jactl is a new programming language for JVM based applications. It provides a secure way for application developers to provide customisation and extension capabilities to their users but can also be used for commandline scripts. An interactive REPL is provided for testing out code snippets.