This is a minimal implementation of a Java delegate for the Cantaloupe image server (version 5.0).

The idea is to use Gradle to build a JAR file that declares an implementation of Cantaloupe's e.i.l.c.delegate.JavaDelegate service. So you must have Gradle installed, but that is the only dependency. Of course, you could also use Maven, or some other tool, or no tool--this is just an example.

1. Edit build.gradle and change the paths in the dependencies section as commented.
2. ./gradlew build

Your JAR file is now ready and waiting in the build/libs directory. Copy it somewhere and add it to the classpath of your Cantaloupe invocation:

java -cp cantaloupe-5.0.jar:/path/to/MyJavaDelegate.jar \
    -Dcantaloupe.config=/path/to/cantaloupe.properties \
    edu.illinois.library.cantaloupe.StandaloneEntry

There is no need for any configuration. Cantaloupe will check for it automatically and only fall back to the Ruby delegate script if necessary.

When developing a Java delegate, keep in mind that almost all of Cantaloupe's Java API (everything outside of the e.i.l.c.delegate package, and even most of the classes within it) is considered private.