Add Lifecycle hooks

[pith]

Currently start() and stop() methods comes from the Plugin interface. It can be a good idea to move then to a new Lifecycle interface. The AbstractPlugin should extends this new interface for compatibility.

It will allow application developers to easily start/stop resources without creating a Plugin. Lifecycle implementations can be scanned during the init phase so there will be no need for ServiceLoader here.

[ejemba]

I think it is a good idea !
Let us think what can be the downside of this.
Why do not create a plugin that will do this exact thing ?
Will the Resource be injected ? or Injectable ? both ?
I imagine having this can be great.
Does plugin and resource really need to share this interface ?

[pith]

Yes they should be injectable. Exactly like plugins currently.

And Yes, I think it should be the same interface. It's frequent that plugins don't implement lifecycle methods. So I think these methods could be extracted as a separate concern.

The kernel will start/stop all the Lifecycle implementations whether they are plugins or not. And not all the plugins have to implements Lifecycle.

[ejemba]

@pith you're right. This is a must for the 1.0 milestone.

I wonder If we might or not fullfill the JSR 250 which purpose is Resource Management.
https://en.wikipedia.org/wiki/JSR_250

We have to be carefull that when we scan for Lifecycle we do not reach plugin themselves.

[ejemba]

I think the JSR 250 is also a must have but in another issue.
Adding jsr250 annotations on injected pojo might also be a good addition to the kernel.
I create the issue.