| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.twill.discovery; |
| |
| import org.apache.twill.common.Cancellable; |
| |
| import java.util.concurrent.Executor; |
| |
| /** |
| * Represents the result of service discovery. It extends from |
| * {@link Iterable} that gives set of latest {@link Discoverable} every time when |
| * {@link #iterator()} is invoked. |
| */ |
| public interface ServiceDiscovered extends Iterable<Discoverable> { |
| |
| /** |
| * Represents a callback for watching changes in the discovery list. |
| * |
| * @see #watchChanges(ServiceDiscovered.ChangeListener, java.util.concurrent.Executor) |
| */ |
| interface ChangeListener { |
| |
| /** |
| * This method will be invoked when the discovery list changed. |
| * |
| * @param serviceDiscovered The {@link ServiceDiscovered} that this listener is attached to. |
| */ |
| void onChange(ServiceDiscovered serviceDiscovered); |
| } |
| |
| /** |
| * Returns the name of the service being discovered. |
| * |
| * @return Name of the service. |
| */ |
| String getName(); |
| |
| /** |
| * Registers a {@link ChangeListener} to watch for changes in the discovery list. |
| * The {@link ChangeListener#onChange(ServiceDiscovered)} method will be triggered when start watching, |
| * and on every subsequent changes in the discovery list. |
| * |
| * @param listener A {@link ChangeListener} to watch for changes. |
| * @param executor A {@link Executor} for issuing call to the given listener. |
| * @return A {@link Cancellable} to cancel the watch. |
| */ |
| Cancellable watchChanges(ChangeListener listener, Executor executor); |
| |
| /** |
| * Checks if the given discoverable contains in the current discovery list. |
| * |
| * @param discoverable The {@link Discoverable} to check for. |
| * @return {@code true} if it exists, {@code false} otherwise. |
| */ |
| boolean contains(Discoverable discoverable); |
| } |