Class HttpMessageDecoder

  extended by
      extended by org.jboss.netty.handler.codec.replay.ReplayingDecoder<HttpMessageDecoder.State>
          extended by org.jboss.netty.handler.codec.http.HttpMessageDecoder
All Implemented Interfaces:
ChannelHandler, ChannelUpstreamHandler
Direct Known Subclasses:
HttpRequestDecoder, HttpResponseDecoder, RtspMessageDecoder

public abstract class HttpMessageDecoder
extends ReplayingDecoder<HttpMessageDecoder.State>

Decodes ChannelBuffers into HttpMessages and HttpChunks.

Parameters that prevents excessive memory consumption

maxInitialLineLength The maximum length of the initial line (e.g. "GET / HTTP/1.0" or "HTTP/1.0 200 OK") If the length of the initial line exceeds this value, a TooLongFrameException will be raised.
maxHeaderSize The maximum length of all headers. If the sum of the length of each header exceeds this value, a TooLongFrameException will be raised.
maxChunkSize The maximum length of the content or each chunk. If the content length (or the length of each chunk) exceeds this value, the content or chunk will be split into multiple HttpChunks whose length is maxChunkSize at maximum.

Chunked Content

If the content of an HTTP message is greater than maxChunkSize or the transfer encoding of the HTTP message is 'chunked', this decoder generates one HttpMessage instance and its following HttpChunks per single HTTP message to avoid excessive memory consumption. For example, the following HTTP message:
 GET / HTTP/1.1
 Transfer-Encoding: chunked

 Content-MD5: ...
 [blank line]
triggers HttpRequestDecoder to generate 4 objects:
  1. An HttpRequest whose chunked property is true,
  2. The first HttpChunk whose content is 'abcdefghijklmnopqrstuvwxyz',
  3. The second HttpChunk whose content is '1234567890abcdef', and
  4. An HttpChunkTrailer which marks the end of the content.
If you prefer not to handle HttpChunks by yourself for your convenience, insert HttpChunkAggregator after this decoder in the ChannelPipeline. However, please note that your server might not be as memory efficient as without the aggregator.


Please note that this decoder is designed to be extended to implement a protocol derived from HTTP, such as RTSP and ICAP. To implement the decoder of such a derived protocol, extend this class and implement all abstract methods properly.

$Rev: 2370 $, $Date: 2010-10-19 14:40:44 +0900 (Tue, 19 Oct 2010) $
The Netty Project, Andy Taylor (, Trustin Lee

Nested Class Summary
protected static class HttpMessageDecoder.State
          The internal state of HttpMessageDecoder.
Nested classes/interfaces inherited from interface
Constructor Summary
protected HttpMessageDecoder()
          Creates a new instance with the default maxInitialLineLength (4096}, maxHeaderSize (8192), and maxChunkSize (8192).
protected HttpMessageDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize)
          Creates a new instance with the specified parameters.
Method Summary
protected abstract  HttpMessage createMessage(String[] initialLine)
protected  Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, HttpMessageDecoder.State state)
          Decodes the received packets so far into a frame.
protected  boolean isContentAlwaysEmpty(HttpMessage msg)
protected abstract  boolean isDecodingRequest()
Methods inherited from class org.jboss.netty.handler.codec.replay.ReplayingDecoder
actualReadableBytes, channelClosed, channelDisconnected, checkpoint, checkpoint, decodeLast, exceptionCaught, getState, internalBuffer, messageReceived, setState
Methods inherited from class
channelBound, channelConnected, channelInterestChanged, channelOpen, channelUnbound, childChannelClosed, childChannelOpen, handleUpstream, writeComplete
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail


protected HttpMessageDecoder()
Creates a new instance with the default maxInitialLineLength (4096}, maxHeaderSize (8192), and maxChunkSize (8192).


protected HttpMessageDecoder(int maxInitialLineLength,
                             int maxHeaderSize,
                             int maxChunkSize)
Creates a new instance with the specified parameters.

Method Detail


protected Object decode(ChannelHandlerContext ctx,
                        Channel channel,
                        ChannelBuffer buffer,
                        HttpMessageDecoder.State state)
                 throws Exception
Description copied from class: ReplayingDecoder
Decodes the received packets so far into a frame.

Specified by:
decode in class ReplayingDecoder<HttpMessageDecoder.State>
ctx - the context of this handler
channel - the current channel
buffer - the cumulative buffer of received packets so far. Note that the buffer might be empty, which means you should not make an assumption that the buffer contains at least one byte in your decoder implementation.
state - the current decoder state (null if unused)
the decoded frame


protected boolean isContentAlwaysEmpty(HttpMessage msg)


protected abstract boolean isDecodingRequest()


protected abstract HttpMessage createMessage(String[] initialLine)
                                      throws Exception

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