Is there a good opensource service/subscription manager engine that contains things like service dependencies (i.e. if I choose service A, I also need Service B and Service C), subscription types, start and termination etc...
I'm building a site that sells various services and subscriptions and would prefer not to have to write that code as I'm pretty sure it's been done many times over (e.g. in e-commerce sw), but I'd prefer a small library / egine instead of having to integrate with an e-shop.
If your "Service" is just Java classes/package/modules then you can use Spring or any other DI container that supports lifecycle hookups.
If by "Service" you mean something big/bloated/enterprise you can also look into OSGI.
But for a small/library engine I suggest you look at plexus and picocontainer.