org.jboss.netty.handler.codec.http

Class HttpMessageDecoder

java.lang.Object

org.jboss.netty.channel.SimpleChannelUpstreamHandler

org.jboss.netty.handler.codec.frame.FrameDecoder

org.jboss.netty.handler.codec.replay.ReplayingDecoder<HttpMessageDecoder.State>

org.jboss.netty.handler.codec.http.HttpMessageDecoder

All Implemented Interfaces:

ChannelHandler, ChannelUpstreamHandler, LifeCycleAwareChannelHandler

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

Name	Meaning
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

 1a
 abcdefghijklmnopqrstuvwxyz
 10
 1234567890abcdef
 0
 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.

Extensibility

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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	HttpMessageDecoder.State The internal state of HttpMessageDecoder.

Nested classes/interfaces inherited from interface org.jboss.netty.channel.ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
private long	chunkSize
private ChannelBuffer	content
private int	contentRead
private int	headerSize
private int	maxChunkSize
private int	maxHeaderSize
private int	maxInitialLineLength
private HttpMessage	message

Fields inherited from class org.jboss.netty.handler.codec.frame.FrameDecoder

cumulation, DEFAULT_MAX_COMPOSITEBUFFER_COMPONENTS

Constructor Summary

Constructors

Modifier	Constructor and Description
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

Modifier and Type	Method and Description
protected abstract HttpMessage	createMessage(java.lang.String[] initialLine)
protected java.lang.Object	decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, HttpMessageDecoder.State state) Decodes the received packets so far into a frame.
private static int	findEndOfString(java.lang.String sb)
private static int	findNonWhitespace(java.lang.String sb, int offset)
private static int	findWhitespace(java.lang.String sb, int offset)
private static int	getChunkSize(java.lang.String hex)
protected boolean	isContentAlwaysEmpty(HttpMessage msg)
protected abstract boolean	isDecodingRequest()
private java.lang.Object	readFixedLengthContent(ChannelBuffer buffer)
private java.lang.String	readHeader(ChannelBuffer buffer)
private HttpMessageDecoder.State	readHeaders(ChannelBuffer buffer)
private static java.lang.String	readLine(ChannelBuffer buffer, int maxLineLength)
private HttpChunkTrailer	readTrailingHeaders(ChannelBuffer buffer)
private java.lang.Object	reset()
private void	resetState()
private static void	skipControlCharacters(ChannelBuffer buffer)
private static java.lang.String[]	splitHeader(java.lang.String sb)
private static java.lang.String[]	splitInitialLine(java.lang.String sb)

Methods inherited from class org.jboss.netty.handler.codec.replay.ReplayingDecoder

checkpoint, checkpoint, cleanup, decode, decodeLast, decodeLast, getState, internalBuffer, messageReceived, setState

Methods inherited from class org.jboss.netty.handler.codec.frame.FrameDecoder

actualReadableBytes, afterAdd, afterRemove, appendToCumulation, beforeAdd, beforeRemove, channelClosed, channelDisconnected, exceptionCaught, extractFrame, getMaxCumulationBufferCapacity, getMaxCumulationBufferComponents, isUnfold, newCumulationBuffer, replace, setMaxCumulationBufferCapacity, setMaxCumulationBufferComponents, setUnfold, unfoldAndFireMessageReceived, updateCumulation

Methods inherited from class org.jboss.netty.channel.SimpleChannelUpstreamHandler

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

Field Detail

maxInitialLineLength

private final int maxInitialLineLength

maxHeaderSize

private final int maxHeaderSize

maxChunkSize

private final int maxChunkSize

message

private HttpMessage message

content

private ChannelBuffer content

chunkSize

private long chunkSize

headerSize

private int headerSize

contentRead

private int contentRead

Constructor Detail

HttpMessageDecoder

protected HttpMessageDecoder()

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

HttpMessageDecoder

protected HttpMessageDecoder(int maxInitialLineLength,
                             int maxHeaderSize,
                             int maxChunkSize)

Creates a new instance with the specified parameters.

Method Detail

decode

protected java.lang.Object decode(ChannelHandlerContext ctx,
                                  Channel channel,
                                  ChannelBuffer buffer,
                                  HttpMessageDecoder.State state)
                           throws java.lang.Exception

Description copied from class: ReplayingDecoder

Decodes the received packets so far into a frame.

Specified by:

decode in class ReplayingDecoder<HttpMessageDecoder.State>

Parameters:

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)

Returns:

the decoded frame

Throws:

java.lang.Exception

isContentAlwaysEmpty

protected boolean isContentAlwaysEmpty(HttpMessage msg)

reset

private java.lang.Object reset()

resetState

private void resetState()

skipControlCharacters

private static void skipControlCharacters(ChannelBuffer buffer)

readFixedLengthContent

private java.lang.Object readFixedLengthContent(ChannelBuffer buffer)

readHeaders

private HttpMessageDecoder.State readHeaders(ChannelBuffer buffer)
                                      throws TooLongFrameException

Throws:

TooLongFrameException

readTrailingHeaders

private HttpChunkTrailer readTrailingHeaders(ChannelBuffer buffer)
                                      throws TooLongFrameException

Throws:

TooLongFrameException

readHeader

private java.lang.String readHeader(ChannelBuffer buffer)
                             throws TooLongFrameException

Throws:

TooLongFrameException

isDecodingRequest

protected abstract boolean isDecodingRequest()

createMessage

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

Throws:

java.lang.Exception

getChunkSize

private static int getChunkSize(java.lang.String hex)

readLine

private static java.lang.String readLine(ChannelBuffer buffer,
                                         int maxLineLength)
                                  throws TooLongFrameException

Throws:

TooLongFrameException

splitInitialLine

private static java.lang.String[] splitInitialLine(java.lang.String sb)

splitHeader

private static java.lang.String[] splitHeader(java.lang.String sb)

findNonWhitespace

private static int findNonWhitespace(java.lang.String sb,
                                     int offset)

findWhitespace

private static int findWhitespace(java.lang.String sb,
                                  int offset)

findEndOfString

private static int findEndOfString(java.lang.String sb)