io.netty.handler.codec.http2

Class Http2MultiplexCodec

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.http2.Http2ConnectionHandler

io.netty.handler.codec.http2.Http2FrameCodec

io.netty.handler.codec.http2.Http2MultiplexCodec

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler, Http2LifecycleManager

@UnstableApi
public class Http2MultiplexCodec
extends Http2FrameCodec

An HTTP/2 handler that creates child channels for each stream.

When a new stream is created, a new Channel is created for it. Applications send and receive Http2StreamFrames on the created channel. ByteBufs cannot be processed by the channel; all writes that reach the head of the pipeline must be an instance of Http2StreamFrame. Writes that reach the head of the pipeline are processed directly by this handler and cannot be intercepted.

The child channel will be notified of user events that impact the stream, such as Http2GoAwayFrame and Http2ResetFrame, as soon as they occur. Although Http2GoAwayFrame and Http2ResetFrame signify that the remote is ignoring further communication, closing of the channel is delayed until any inbound queue is drained with Channel.read(), which follows the default behavior of channels in Netty. Applications are free to close the channel in response to such events if they don't have use for any queued messages.

Outbound streams are supported via the Http2StreamChannelBootstrap.

ChannelConfig.setMaxMessagesPerRead(int) and ChannelConfig.setAutoRead(boolean) are supported.

Reference Counting

Some Http2StreamFrames implement the ReferenceCounted interface, as they carry reference counted objects (e.g. ByteBufs). The multiplex codec will call ReferenceCounted.retain() before propagating a reference counted object through the pipeline, and thus an application handler needs to release such an object after having consumed it. For more information on reference counting take a look at http://netty.io/wiki/reference-counted-objects.html

Channel Events

A child channel becomes active as soon as it is registered to an EventLoop. Therefore, an active channel does not map to an active HTTP/2 stream immediately. Only once a Http2HeadersFrame has been successfully sent or received, does the channel map to an active HTTP/2 stream. In case it is not possible to open a new HTTP/2 stream (i.e. due to the maximum number of active streams being exceeded), the child channel receives an exception indicating the cause and is closed immediately thereafter.

Writability and Flow Control

A child channel observes outbound/remote flow control via the channel's writability. A channel only becomes writable when it maps to an active HTTP/2 stream and the stream's flow control window is greater than zero. A child channel does not know about the connection-level flow control window. ChannelHandlers are free to ignore the channel's writability, in which case the excessive writes will be buffered by the parent channel. It's important to note that only Http2DataFrames are subject to HTTP/2 flow control.

Nested Class Summary

Nested classes/interfaces inherited from class io.netty.handler.codec.ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields inherited from class io.netty.handler.codec.ByteToMessageDecoder

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Method Summary

Modifier and Type	Method and Description
void	channelReadComplete(ChannelHandlerContext ctx) Notifies any child streams of the read completion.
void	flush(ChannelHandlerContext ctx) Called once a flush operation is made.
void	handlerAdded0(ChannelHandlerContext ctx)
void	handlerRemoved0(ChannelHandlerContext ctx) Gets called after the ByteToMessageDecoder was removed from the actual context and it doesn't handle events anymore.

Methods inherited from class io.netty.handler.codec.http2.Http2FrameCodec

handlerAdded, isGracefulShutdownComplete, onConnectionError, onStreamError, userEventTriggered, write

Methods inherited from class io.netty.handler.codec.http2.Http2ConnectionHandler

bind, channelActive, channelInactive, channelWritabilityChanged, close, closeStream, closeStreamLocal, closeStreamRemote, connect, connection, decode, decoder, deregister, disconnect, encoder, exceptionCaught, frameWriter, goAway, gracefulShutdownTimeoutMillis, gracefulShutdownTimeoutMillis, handleServerHeaderDecodeSizeError, onError, onHttpClientUpgrade, onHttpServerUpgrade, read, resetStream

Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder

actualReadableBytes, callDecode, channelRead, decodeLast, discardSomeReadBytes, handlerRemoved, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelRegistered, channelUnregistered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, isSharable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.channel.ChannelHandler

handlerRemoved

Method Detail

handlerAdded0

public final void handlerAdded0(ChannelHandlerContext ctx)
                         throws Exception

Throws:

Exception

handlerRemoved0

public final void handlerRemoved0(ChannelHandlerContext ctx)
                           throws Exception

Description copied from class: ByteToMessageDecoder

Gets called after the ByteToMessageDecoder was removed from the actual context and it doesn't handle events anymore.

Overrides:

handlerRemoved0 in class Http2ConnectionHandler

Throws:

Exception

channelReadComplete

public final void channelReadComplete(ChannelHandlerContext ctx)
                               throws Exception

Notifies any child streams of the read completion.

Specified by:

channelReadComplete in interface ChannelInboundHandler

Overrides:

channelReadComplete in class Http2ConnectionHandler

Throws:

Exception

flush

public final void flush(ChannelHandlerContext ctx)

Description copied from interface: ChannelOutboundHandler

Called once a flush operation is made. The flush operation will try to flush out all previous written messages that are pending.

Specified by:

flush in interface ChannelOutboundHandler

Overrides:

flush in class Http2ConnectionHandler

Parameters:

ctx - the ChannelHandlerContext for which the flush operation is made