83 lines
3.6 KiB
Java
83 lines
3.6 KiB
Java
/*
|
|
* JBoss, Home of Professional Open Source
|
|
*
|
|
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
|
|
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
|
|
* full listing of individual contributors.
|
|
*
|
|
* This is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU Lesser General Public License as
|
|
* published by the Free Software Foundation; either version 2.1 of
|
|
* the License, or (at your option) any later version.
|
|
*
|
|
* This software is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with this software; if not, write to the Free
|
|
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
|
|
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
|
|
*/
|
|
package org.jboss.netty.channel;
|
|
|
|
/**
|
|
* An I/O event or I/O request associated with a {@link Channel}.
|
|
* <p>
|
|
* A {@link ChannelEvent} is supposed to be handled by the
|
|
* {@link ChannelPipeline} which is owned by the {@link Channel} that
|
|
* the event belongs to. Once an event is sent to a {@link ChannelPipeline},
|
|
* it is handled by a list of {@link ChannelHandler}s.
|
|
*
|
|
* <h3>Upstream events and downstream events, and their interpretation</h3>
|
|
* <p>
|
|
* Every event can be either an upstream event or a downstream event.
|
|
* If an event flows from the first handler to the last handler in a
|
|
* {@link ChannelPipeline}, we call it an upstream event and say <strong>"an
|
|
* event goes upstream."</strong> If an event flows from the last handler to
|
|
* the first handler in a {@link ChannelPipeline}, we call it a downstream
|
|
* event and say <strong>"an event goes downstream."</strong> (Please refer
|
|
* to the diagram in {@link ChannelPipeline} for more explanation.)
|
|
* <p>
|
|
* A {@link ChannelEvent} is interpreted differently by a {@link ChannelHandler}
|
|
* depending on whether the event is an upstream event or a downstream event.
|
|
* An upstream event represents the notification of what happened in the past.
|
|
* By contrast, a downstream event represents the request of what should happen
|
|
* in the future. For example, a {@link MessageEvent} represents the
|
|
* notification of a received message when it goes upstream, while it
|
|
* represents the request of writing a message when it goes downstream.
|
|
*
|
|
* <h4>Additional resources worth reading</h4>
|
|
* <p>
|
|
* Please refer to the documentation of {@link ChannelHandler} and its sub-types
|
|
* ({@link ChannelUpstreamHandler} for upstream events and
|
|
* {@link ChannelDownstreamHandler} for downstream events) to find out how
|
|
* a {@link ChannelEvent} is interpreted depending on the type of the handler
|
|
* more in detail.
|
|
*
|
|
* @author The Netty Project (netty-dev@lists.jboss.org)
|
|
* @author Trustin Lee (tlee@redhat.com)
|
|
*
|
|
* @version $Rev$, $Date$
|
|
*
|
|
* @apiviz.landmark
|
|
* @apiviz.composedOf org.jboss.netty.channel.ChannelFuture
|
|
*/
|
|
public interface ChannelEvent {
|
|
|
|
/**
|
|
* Returns the {@link Channel} which is associated with this event.
|
|
*/
|
|
Channel getChannel();
|
|
|
|
/**
|
|
* Returns the {@link ChannelFuture} which is associated with this event.
|
|
* If this event is an upstream event, this method will always return a
|
|
* {@link SucceededChannelFuture} because the event has occurred already.
|
|
* If this event is a downstream event (i.e. I/O request), the returned
|
|
* future will be notified when the I/O request succeeds or fails.
|
|
*/
|
|
ChannelFuture getFuture();
|
|
}
|