Restarting Apache Felix - java-8

Question

I am doing a self updating application using Apache Felix and I can't seem to forcibly restart Felix after update. I did some tricks to simulate the restart process by using some kind of application State.
public class LauncherActivator implements BundleActivator {
public static LauncherState State;
#Override
public void start(BundleContext context) throws Exception {
...
LauncherApplication.State = LauncherState.READY;
Platform.runLater(() -> {
try {
new LauncherApplication().start();
} catch (Exception ex) {
Logger.getLogger(LauncherActivator.class.getName()).log(Level.SEVERE, null, ex);
}
});
}
}
If there are updates detected I would just change the global state to LauncherAppliation.State = LauncherState.RESTART; if the application detects the change in State I will just simply call BUNDLE_MAP.get('application.activator').update();, BUNDLE_MAP is some kind of a HashMap that stores all running bundles on start.
I tested it and it worked, I can see in the logs that the activator bundle is being updated and the simple restart mechanism reruns the activator bundle but there are times that it doesn't rerun the activator bundle and the bundle state is already ACTIVE.
So what would be the right way to restart Apache Felix using the activator bundle or any bundle in general?

Answer 1

It is all in the documentation all this time!
Starting the Framework Instance
The start() method is used to start the framework instance. If the init() method was not invoked prior to calling start(), then it is invoked by start(). The two methods result in two different framework state transitions:
init() results in the framework instance in the Bundle.STARTING state.
start() results in the framework instance in the Bundle.ACTIVE state.
The init() method is necessary since the framework does not have a BundleContext when it is first created, so a transition to the Bundle.STARTING state is required to acquire its context (via Bundle.getBundleContext()) for performing various tasks, such as installing bundles. Note that the Felix framework also provides the felix.systembundle.activators property that serves a similar purpose, but is not standard. After the init() method completes, the follow actions have been performed:
Event handling is enabled.
The security manager is installed if it is enabled.
The framework is set to start level 0.
All bundles in the bundle caches are reified and their state is set to Bundle.INSTALLED.
The framework gets a valid BundleContext.
All framework-provided services are made available (e.g., PackageAdmin, StartLevel, etc.).
The framework enters the Bundle.STARTING state.
A call to start() is necessary to start the framework instance, if the init() method is invoked manually. Invoking init() or start() on an already started framework as no effect.
Stopping the Framework Instance
To stop the framework instance, invoke the stop() method, which will asynchronously stop the framework. To know when the framework has finished its shutdown sequence, use the waitForStop() method to wait until it is complete. A stopped framework will be in the Bundle.RESOLVED state. It is possible to restart the framework, using the normal combination of init()/start() methods as previously described.
Launching a Framework
Launching a framework is fairly simple and involves only four steps:
Define some configuration properties.
Obtain framework factory.
Use factory to create framework with the configuration properties.
Invoke the Framework.start() method.
In reality, the first step is optional, since all properties will have reasonable defaults, but if you are creating a launcher you will generally want to more than that, such as automatically installing and starting bundles when you start the framework instance. The default Felix launcher defines reusable functionality to automatically install and/or start bundles upon framework startup.