001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.spi;
018
019import java.util.List;
020
021/**
022 * Allows SPIs to implement custom server list strategies for the Service Call EIP.
023 *
024 * @see ServiceCallLoadBalancer
025 * @see ServiceCallServer
026 */
027public interface ServiceCallServerListStrategy<T extends ServiceCallServer> {
028
029    /**
030     * Gets the initial list of servers.
031     * <p/>
032     * This method may return <tt>null</tt> or an empty list.
033     *
034     * @param name the service name
035     */
036    List<T> getInitialListOfServers(String name);
037
038    /**
039     * Gets the updated list of servers.
040     * <p/>
041     * This method can either be called on-demand prior to a service call, or have
042     * a background job that is scheduled to update the list, or a watcher
043     * that triggers when the list of servers changes.
044     *
045     * @param name the service name
046     */
047    List<T> getUpdatedListOfServers(String name);
048
049}