/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/client/RequestDirector.java $
 * $Revision: 676020 $
 * $Date: 2008-07-11 09:38:49 -0700 (Fri, 11 Jul 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.client;

import java.io.IOException;

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

/**
 * A client-side request director.
 * The director decides which steps are necessary to execute a request.
 * It establishes connections and optionally processes redirects and
 * authentication challenges. The director may therefore generate and
 * send a sequence of requests in order to execute one initial request.
 *
 * <br/><b>Note:</b>
 * It is most likely that implementations of this interface will
 * allocate connections, and return responses that depend on those
 * connections for reading the response entity. Such connections
 * MUST be released, but that is out of the scope of a request director.
 *
 * @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
 *
 *
 * <!-- empty lines to avoid svn diff problems -->
 * @version $Revision: 676020 $
 *
 * @since 4.0
 */
public interface RequestDirector {


    /**
     * Executes a request.
     * <br/><b>Note:</b>
     * For the time being, a new director is instantiated for each request.
     * This is the same behavior as for <code>HttpMethodDirector</code>
     * in HttpClient 3.
     *
     * @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 for executing the request
     *
     * @return  the final response to the request.
     *          This is never an intermediate response with status code 1xx.
     *
     * @throws HttpException            in case of a problem
     * @throws IOException              in case of an IO problem
     *                                     or if the connection was aborted
     */
    HttpResponse execute(HttpHost target, HttpRequest request,
                         HttpContext context)
        throws HttpException, IOException
        ;

} // class ClientRequestDirector