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/*
 * Copyright 2014. Vladislav Dolgikh
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.elusive_code.newsboy;


/**
 * This interface represents event source, e.g. object that produces events to which others may subscribe
 * 
 *     To receive events object must have public method with zero or one argument
 *     marked with {@link com.elusive_code.newsboy.Subscribe} annotation.

 *     This object should be passed to {@link com.elusive_code.newsboy.EventService#subscribe(Object)}.

 * 
 * 
 *     If event handling method has one argument,
 *     listener will be notified of the events that fit the type of that argument.
 *     If event handling method has no arguments,
 *     listener will notified of the events that fit {@link Subscribe#eventType()}
 * 
 *
 * @see com.elusive_code.newsboy.Subscribe com.elusive_code.newsboy.EventService
 * @see AsyncEventService
 * @author Vladislav Dolgikh
 */
public interface EventSource {

    /**
     * Subscribe for events from this EventService.
     *
     * Subscriber should have method or methods marked with
     * {@link com.elusive_code.newsboy.Subscribe}
     * annotation.

     * If annotated method has no arguments, it still will be subscribed and notified
     * of the events of type specified in annotation parameter.
     * 
     *
     * @param listener listener to receive events
     * @see com.elusive_code.newsboy.Subscribe
     */
    void subscribe(Object listener);

    /**
     * Unsubscribe listener from events from this EventService
     * @param listener listener to
     */
    void unsubscribe(Object listener);
}