I apologize for attempting this monstrosity, but... It is forced on me.
I have a .jar implementing logic that I receive prebuilt. This .jar exports some API you can use (... in Java...) to request information about file-system items you hand in as paths.
This .jar is compatible with Java 11, and runs with the "Zulu" Java VM.
I need to "wrap" it in some way that will behave like a global daemon, launched and managed by launchd, available to other components (apps, user-agents and global-daemons) in our product.
Running it as a global daemon is a breeze - simply place a .plist in /Library/LaunchDaemons/myMonster.plist and have the java -jar <path to my .jar> arguments, throw in a 'keep alive' option, and it runs.
Now... It makes sense for other components to pass it "queries" and receive "results" via XPC connection. First, because this way I could deny connection to unknown components, I could have a secure connection, and also integrate nicely from the other components ObjC code.
However... XPC isn't something available in JDK, and the actual executable launched is the Zulu java command binary of course, that I can't modify.
So... I tried to use JNA (Java Native Access) and (with much tears and sweat) get my java code to create an xpc connection (as client! not "service") to another XPC Service already running.
Also, I was only able to do it via xpc.h (the old C API. not ObjC NSXPCConnection as of yet).
The documentation on old C-style XPC Services is very thin, almost nothing... and the only thing about Creating an XPC Service of this style says:
// If you are writing a low-level (C-based) XPC service, implement a minimal main function to register your event handler, as shown in the following code listing. Replace my_event_handler with the name of your event handler function.
int main(int argc, const char *argv[]) {
xpc_main(my_event_handler);
// The xpc_main() function never returns.
exit(EXIT_FAILURE);
}
Which of course, I can't do! I don't control the process 'main()' entry point (it's java...) and I can't block anything.
So here's my question:
- Where in the lifecycle of a Java program can I call on my native code to set up The XPC Service?
- Is there a non-blocking alternative to xpc_main(my_event_handler) I can use to start my service?
I know this calls for multi-disciplinary knowledge but any hint or idea will be greatly appreciated.
Thanks!
