andreacavalli/netty5
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Added documentation on how to implement protocol multiplexer

Browse Source
This commit is contained in:
Trustin Lee 2009-07-23 07:10:30 +00:00
parent c4449a170d
commit 338a5cba4a
2 changed files with 78 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
src/main/java/org/jboss/netty/handler/codec/frame/FrameDecoder.java
View File

@ -28,7 +28,9 @@ import java.util.concurrent.atomic.AtomicReference;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandler;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ChannelUpstreamHandler;
@ -36,6 +38,7 @@ import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.handler.codec.replay.ReplayingDecoder;
/**
* Decodes the received {@link ChannelBuffer}s into a meaningful frame object.
@ -137,6 +140,43 @@ import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
* {@link ChannelUpstreamHandler} receives a {@link MessageEvent} which
* contains a POJO rather than a {@link ChannelBuffer}.
*
* <h3>Replacing a decoder with another decoder in a pipeline</h3>
* <p>
* If you are going to write a protocol multiplexer, you will probably want to
* replace a {@link FrameDecoder} (protocol detector) with another
* {@link FrameDecoder} or {@link ReplayingDecoder} (actual protocol decoder).
* It is not possible to achieve this simply by calling
* {@link ChannelPipeline#replace(ChannelHandler, String, ChannelHandler)}, but
* some additional steps are required:
* <pre>
* public class FirstDecoder extends FrameDecoder {
*
* public FirstDecoder() {
* super(true); // Enable unfold
* }
*
* protected Object decode(ChannelHandlerContext ctx, Channel ch, ChannelBuffer buf) {
* ...
* // Decode the first message
* Object firstMessage = ...;
*
* // Add the second decoder
* ctx.getPipeline().addLast("second", new SecondDecoder());
*
* // Remove the first decoder (me)
* ctx.getPipeline().remove(this);
*
* if (buf.readable()) {
* // Hand off the remaining data to the second decoder
* return new Object[] { firstMessage, buf.readBytes(buf.readableBytes()) };
* } else {
* // Nothing to hand off
* return firstMessage;
* }
* }
* }
* </pre>
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*

38
src/main/java/org/jboss/netty/handler/codec/replay/ReplayingDecoder.java
View File

@ -28,7 +28,9 @@ import java.util.concurrent.atomic.AtomicReference;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBufferFactory;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandler;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.Channels;
@ -241,6 +243,42 @@ import org.jboss.netty.handler.codec.frame.FrameDecoder;
* }
* </pre>
*
* <h3>Replacing a decoder with another decoder in a pipeline</h3>
* <p>
* If you are going to write a protocol multiplexer, you will probably want to
* replace a {@link ReplayingDecoder} (protocol detector) with another
* {@link ReplayingDecoder} or {@link FrameDecoder} (actual protocol decoder).
* It is not possible to achieve this simply by calling
* {@link ChannelPipeline#replace(ChannelHandler, String, ChannelHandler)}, but
* some additional steps are required:
* <pre>
* public class FirstDecoder extends ReplayingDecoder&lt;VoidEnum&gt; {
*
* public FirstDecoder() {
* super(true); // Enable unfold
* }
*
* protected Object decode(ChannelHandlerContext ctx, Channel ch, ChannelBuffer buf, VoidEnum state) {
* ...
* // Decode the first message
* Object firstMessage = ...;
*
* // Add the second decoder
* ctx.getPipeline().addLast("second", new SecondDecoder());
*
* // Remove the first decoder (me)
* ctx.getPipeline().remove(this);
*
* if (buf.readable()) {
* // Hand off the remaining data to the second decoder
* return new Object[] { firstMessage, buf.readBytes(<b>super.actualReadableBytes()</b>) };
* } else {
* // Nothing to hand off
* return firstMessage;
* }
* }
* </pre>
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*