001// Copyright 2004, 2005 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007//     http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.hivemind.service;
016
017import org.apache.hivemind.Location;
018
019/**
020 * Service used to link two other services together using event notifications. The service producer
021 * will have the consumer registered as a listener.
022 * 
023 * @author Howard Lewis Ship
024 */
025public interface EventLinker
026{
027    /**
028     * Adds the consumer as a listener of events published by the producer. Typically, the producer
029     * is a service, and the consumer is some other service's core implementation.
030     * 
031     * @param producer
032     *            the object which will be publishing the events.
033     * @param eventSetName
034     *            the name of an event set; the consumer will only be registered for that set of
035     *            events.
036     * @param consumer
037     *            the object which will be added as a listener.
038     * @param location
039     *            used when reporting errors, may be null
040     * @return true on success, false if there was any failure (which may mean only partial
041     *         registration).
042     */
043    public void addEventListener(Object producer, String eventSetName, Object consumer,
044            Location location);
045}