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package org.glassfish.jersey.server.monitoring;
import javax.ws.rs.ConstrainedTo;
import javax.ws.rs.RuntimeType;
import org.glassfish.jersey.spi.Contract;
/**
* Jersey specific provider that listens to {@link ApplicationEvent application events}.
* The implementation of this interface will be called for two kind of events:
* application events and {@link RequestEvent request events}. This interface will listen to
* all {@link org.glassfish.jersey.server.monitoring.ApplicationEvent.Type application event types}
* but only to first request event which is the {@link RequestEvent.Type#START}. On this event the
* application event listener can decide whether it will listen to the request and return {@link RequestEventListener
* request event listener} for listening to further request events.
* }
* <p/>
* The implementation of this interface can be registered as a standard Jersey/JAX-RS provider
* by annotating with {@link javax.ws.rs.ext.Provider @Provider} annotation in the case of
* class path scanning, by registering as a provider using {@link org.glassfish.jersey.server.ResourceConfig}
* or by returning from {@link javax.ws.rs.core.Application#getClasses()}
* or {@link javax.ws.rs.core.Application#getSingletons()}}. The provider can be registered only on the server
* side.
* <p/>
* Application event listener can read data of events but must not modify them in any way. The implementation
* must be thread safe (the methods might be called from different threads).
*
* @author Miroslav Fuksa
*/
@Contract
@ConstrainedTo(RuntimeType.SERVER)
public interface ApplicationEventListener {
/**
* Process the application {@code event}. This method is called when new event occurs.
*
* @param event Application event.
*/
public void onEvent(ApplicationEvent event);
/**
* Process a new request and return a {@link RequestEventListener request event listener} if
* listening to {@link RequestEvent request events} is required. The method is called once for
* each new incoming request. If listening to the request is required then request event must be returned
* from the method. Such a request event listener will receive all request events that one request. If listening
* to request event for the request is not required then {@code null} must be returned
* from the method (do not return empty mock listener in these
* cases as it will have negative performance impact).
*
* @param requestEvent Event of type {@link RequestEvent.Type#START}.
* @return Request event listener that will monitor the events of the request
* connected with {@code requestEvent}; null otherwise.
*/
public RequestEventListener onRequest(RequestEvent requestEvent);
}