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    1   /*
    2    * Copyright 2012 The Netty Project
    3    *
    4    * The Netty Project licenses this file to you under the Apache License,
    5    * version 2.0 (the "License"); you may not use this file except in compliance
    6    * with the License. You may obtain a copy of the License at:
    7    *
    8    *   http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
    12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    13   * License for the specific language governing permissions and limitations
    14   * under the License.
    15   */
    16  package org.jboss.netty.channel;
    17
    18  import java.util.concurrent.Executor;
    19
    20  import org.jboss.netty.channel.group.ChannelGroup;
    21  import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
    22  import org.jboss.netty.util.ExternalResourceReleasable;
    23
    24
    25  /**
    26   * The main interface to a transport that creates a {@link Channel} associated
    27   * with a certain communication entity such as a network socket.  For example,
    28   * the {@link NioServerSocketChannelFactory} creates a channel which has a
    29   * NIO-based server socket as its underlying communication entity.
    30   * <p>
    31   * Once a new {@link Channel} is created, the {@link ChannelPipeline} which
    32   * was specified as a parameter in the {@link #newChannel(ChannelPipeline)}
    33   * is attached to the new {@link Channel}, and starts to handle all associated
    34   * {@link ChannelEvent}s.
    35   *
    36   * <h3>Graceful shutdown</h3>
    37   * <p>
    38   * To shut down a network application service which is managed by a factory.
    39   * you should follow the following steps:
    40   * <ol>
    41   * <li>close all channels created by the factory and their child channels
    42   *     usually using {@link ChannelGroup#close()}, and</li>
    43   * <li>call {@link #releaseExternalResources()}.</li>
    44   * </ol>
    45   * <p>
    46   * For detailed transport-specific information on shutting down a factory,
    47   * please refer to the Javadoc of {@link ChannelFactory}'s subtypes, such as
    48   * {@link NioServerSocketChannelFactory}.
    49   *
    50   * @apiviz.landmark
    51   * @apiviz.has        org.jboss.netty.channel.Channel oneway - - creates
    52   *
    53   * @apiviz.exclude ^org\.jboss\.netty\.channel\.([a-z]+\.)+.*ChannelFactory$
    54   */
    55  public interface ChannelFactory extends ExternalResourceReleasable {
    56
    57      /**
    58       * Creates and opens a new {@link Channel} and attaches the specified
    59       * {@link ChannelPipeline} to the new {@link Channel}.
    60       *
    61       * @param pipeline the {@link ChannelPipeline} which is going to be
    62       *                 attached to the new {@link Channel}
    63       *
    64       * @return the newly open channel
    65       *
    66       * @throws ChannelException if failed to create and open a new channel
    67       */
    68      Channel newChannel(ChannelPipeline pipeline);
    69
    70      /**
    71       * Releases the external resources that this factory depends on to function.
    72       * An external resource is a resource that this factory didn't create by
    73       * itself.  For example, {@link Executor}s that you specified in the factory
    74       * constructor are external resources.  You can call this method to release
    75       * all external resources conveniently when the resources are not used by
    76       * this factory or any other part of your application.  An unexpected
    77       * behavior will be resulted in if the resources are released when there's
    78       * an open channel which is managed by this factory.
    79       */
    80      void releaseExternalResources();
    81  }