org.dspace.kernel.Activator Maven / Gradle / Ivy
/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.kernel;
/**
* An activator is a special type which allows a provider to be plugged into the system by dropping a jar file
* in with the kernel and adding in a hook in the configuration file. Activators are started after the
* initial classes and the service manager have already been started. All classes which implement this
* must have a public empty constructor (takes no parameters) (e.g.
* {@code public MyClass() {}} )
*
* If you want the system to execute your class then you must list it in
* the DSpace configuration with the fully qualified classpath
* (NOTE that the xxx can be anything as long as it is unique):
* {@code activator.xxx = org.dspace.MyClass}
*
*
* {@link #start(ServiceManager)} will be called after the class is created during kernel startup.
* Developers should create their providers/plugins/etc. in this method and
* use the registration methods in the {@link ServiceManager} to register them.
* {@link #stop(ServiceManager)} will be called when the kernel shuts down. Perform any cleanup/shutdown actions
* you like during this phase (unregistering your services here is a good idea).
*
* This is modeled after the OSGi {@code BundleActivator}.
*
* There is another type of activator used in DSpace but it is
* configured via the configuration service only. The class activator
* is configured by creating a config property like this
* (NOTE that the xxx can be anything as long as it is unique):
* {@code activator.class.xxx = org.dspace.MyClass;org.dspace.MyServiceName;constructor}
* Unlike the normal activators, these are started up when the kernel
* core services start and thus can actually be accessed from the
* service manager and referenced in providers and plugins.
*
*
* @author Aaron Zeckoski (azeckoski @ gmail.com)
*/
public interface Activator {
/**
* This is called when the service manager is starting this activator.
* It is only called once.
* It will be called after the core services are started. The ClassLoader used will be the one
* that this class is associated with to ensure all dependencies are available.
*
* This method should be used to startup and register services in most cases but it can be used
* to simply perform some system startup actions if desired.
*
* Exceptions thrown out of this method will not cause the system startup to fail.
*
* @param serviceManager the current system service manager
*/
public void start(ServiceManager serviceManager);
/**
* This is called when the service manager is shutting down this
* activator. It is only called once.
* It will be called before the core services are stopped. The ClassLoader used will be the one
* that this class is associated with to ensure all dependencies are available.
*
* This method should be used to shutdown and unregister services in most cases but it can be used
* to simply perform some system shutdown actions if desired.
*
* Exceptions thrown out of this method will not cause the system shutdown to fail.
*
* WARNING: this can hang the shutdown by performing operations that
* take a long long time or are deadlocked. The developer is
* expected to ensure this does not happen.
*
* @param serviceManager the current system service manager
*/
public void stop(ServiceManager serviceManager);
}