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For those who regularly follow my blog, I like Groovy as a way of scripting given its portability, proximity to Java, its use of the JVM means its really easy to work with. With the extra language features it makes it easy to work with without needing to setup Maven builds to manage dependencies for something simple. As a result, the utils I’ve produced to support Oracle API Platform CS (here) for example are written with Groovy.

However, not everyone is such a fan, or sees Groovy as niche and, to be honest in the last few years Python has made huge in roads in the scripting space. So I can appreciate the preference for Python to be used. This was really brought home to me by a peer review comments for my latest book project. This got me to thinking what options do I have to remove Groovy from the equation, without resulting in needing to mess with maven POM files. The options as I saw it are:

  • Replace any use of Groovy extensions with Java libraries
  • Switch to using Java 11 and the shebang feature (more in a minute)
  • Compile code with Groovyc and package the jars manually including dependencies.

From Java 11, the ability for a single Java file to be executed without compiling etc was introduced – known as shebang (more here). The issue here is a lot of applications have been certified against Java 8, and in an Enterprise environment this is important. Which means either installing Java 11 locally without changing environment variables, or you need to add code to switch Java versions as necessary. The upside being that you can run your code as a script, and then if necessary build it into a jar to distribute. Aside from the need to switch between JDK versions, Java’s language gets ever richer, but Groovy has a nice set of extensions that make JSON object navigation really nice, and these aren’t necessarily in core Java.

Groovy provides a tool to compile Groovy to bytecode for the JVM (i.e. create class files). From which we can create a JAR file with using the javac command. But this doesn’t bundle the Groovy dependencies necessary to run the jar, as a result Groovy still needs to be installed. You could do this through the use of a maven, Gradle or other build tools. But we’re back to creating a POM file or equivalent., and to be honest creating a POM file from scratch is slow going unless everything lines up neatly with file structures, which it won’t because when you produce a script you’re not expecting to need to worry about packages and associated folder structures.

In looking to see if someone had simplified the process I came across this excellent tool scriptjar (more here). Script jar takes the location of the class files, creates a jar file and loads it with the Groovy jar dependencies, and assembles the manifest file etc. Net result, a jar file created in 2 lines that has no Groovy deployment dependencies to use, and will work with older Java versions such as Java 8.

I started out referring to the API tools, but the same mechanism can be applied to the LogSimulator tool I’ve created that allows you to generate or replay existing logs in real-time or faster than real-time, making it easy to test log monitoring setups from a monitored source all the way through (today it only handles log file replaying or the use of the Java native logging).