Extension loading from classpath

[616c]

My Goal

I'm looking for a way to automatically load an extension that is provided as a simple jar in the classpath.

The extension can be successfully loaded if this is entered into a cell:

(new my.path.MyExtension()).install(getKernelInstance())

Problem

Maybe I'm missing something. I would have expected that since JJAVA_LOAD_EXTENSIONS per default is enabled, my extension is found during startup, but it isn't. The service specification in META-INF is provided, I triple-checked this.

As I understand the jjava code, the setup only takes place automatically if the jar is added via %maven magics.

I tried to use JJAVA_STARTUP_SCRIPT, but here getKernelInstance() is not available and org.dflib.jjava.JJava.getKernelInstance() returns null.

Alternatively, if this is intentionally not happening at load time, it would be an option if the kernel instance is available in startup scripts.

[andrus]

I know for sure an extension is loaded when added as an explict notebook dependency, e.g. as %maven my:lib:1.0. Need to doublecheck the behavior when it is already on the classpath...

[616c]

Yes it is. As I see it, in MavenResolver constructor there is an instance of extensionLoader = new ExtensionLoader(); created. But it seems to be the only place where it's used, so it looks like it applies only for %maven magics.