/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/conn/routing/HttpRoutePlanner.java $
 * $Revision: 613654 $
 * $Date: 2008-01-20 11:00:19 -0800 (Sun, 20 Jan 2008) $
 *
 * ====================================================================
 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.conn.routing;

import org.apache.http.HttpException;
import org.apache.http.HttpHost;
import org.apache.http.HttpRequest;
import org.apache.http.protocol.HttpContext;


/**
 * Encapsulates logic to compute a {@link HttpRoute} to a target host.
 * Implementations may for example be based on parameters, or on the
 * standard Java system properties.
 */
public interface HttpRoutePlanner {
    
    /**
     * Determines the route for a request.
     *
     * @param target    the target host for the request.
     *                  Implementations may accept <code>null</code>
     *                  if they can still determine a route, for example
     *                  to a default target or by inspecting the request.
     * @param request   the request to execute
     * @param context   the context to use for the subsequent execution.
     *                  Implementations may accept <code>null</code>.
     *
     * @return  the route that the request should take
     *
     * @throws HttpException    in case of a problem
     */        
    public HttpRoute determineRoute(HttpHost target,
                                    HttpRequest request,
                                    HttpContext context)
        throws HttpException
        ;
    
}