/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * 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.alibaba.dubbo.rpc.cluster;

import java.util.List;

import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.rpc.Invocation;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.RpcException;

/**
 * Router. (SPI, Prototype, ThreadSafe)
 * 
 * <a href="http://en.wikipedia.org/wiki/Routing">Routing</a>
 * 
 * @see com.alibaba.dubbo.rpc.cluster.Cluster#join(Directory)
 * @see com.alibaba.dubbo.rpc.cluster.Directory#list(Invocation)
 * @author chao.liuc
 */
public interface Router extends Comparable<Router> {

    /**
     * get the router url.
     * 
     * @return url
     */
    URL getUrl();

    /**
     * route.
     * 
     * @param invokers
     * @param url refer url
     * @param invocation
     * @return routed invokers
     * @throws RpcException
     */
	<T> List<Invoker<T>> route(List<Invoker<T>> invokers, URL url, Invocation invocation) throws RpcException;

}