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 * 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

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 */



package org.apache.http.conn.routing;



/**

 * Provides directions on establishing a route.

 * Implementations of this interface compare a planned route with

 * a tracked route and indicate the next step required.

 *

 * @since 4.0

 */

public interface HttpRouteDirector {



    /** Indicates that the route can not be established at all. */

    public final static int UNREACHABLE = -1;



    /** Indicates that the route is complete. */

    public final static int COMPLETE = 0;



    /** Step: open connection to target. */

    public final static int CONNECT_TARGET = 1;



    /** Step: open connection to proxy. */

    public final static int CONNECT_PROXY = 2;



    /** Step: tunnel through proxy to target. */

    public final static int TUNNEL_TARGET = 3;



    /** Step: tunnel through proxy to other proxy. */

    public final static int TUNNEL_PROXY = 4;



    /** Step: layer protocol (over tunnel). */

    public final static int LAYER_PROTOCOL = 5;





    /**

     * Provides the next step.

     *

     * @param plan      the planned route

     * @param fact      the currently established route, or

     *                  <code>null</code> if nothing is established

     *

     * @return  one of the constants defined in this interface, indicating

     *          either the next step to perform, or success, or failure.

     *          0 is for success, a negative value for failure.

     */

    public int nextStep(RouteInfo plan, RouteInfo fact);



}