Native image and SPI extensibility

[Stwissel]

In our enterprise apps we have an SPI pattern roughly like this:

interface someInterface {
  UnaryOperator<SomeObject> process(...);
Predicate<SomeContext> pickMe(..);
int priority();
}

We deliver a bunch of classes implementing it to be picked by SPI.
In most deployments clients have some more of them. So they throw a jar with them on the classpath and the SPI picks them up.

We love Native Image and wonder what's the equivalent pattern for extensibility

[dmlloyd]

For native image, you generally have to have everything included at build time. You can usually use the same SPI pattern, but it won't work at run time unless you build in the JARs at the time you build the image.

Basically you (or your client) will need a new native image for each combination of extension JARs, as things stand today.

[Stwissel]

So there isn't a substitute for a classpath. Got it. Thx.

The alternative we are thinking of, luckily deployment is container only, is to run a small jar in the background listening on the EventBus for requests from the native binary. We haven't figured out the exact configuration yet