Interface ChannelUpstreamHandler
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- All Superinterfaces:
ChannelHandler
- All Known Implementing Classes:
AbstractCodecEmbedder.EmbeddedChannelSink
,AbstractTrafficShapingHandler
,AutobahnServerHandler
,Base64Decoder
,BigIntegerDecoder
,BlockingReadHandler
,BufferedWriteHandler
,ChannelTrafficShapingHandler
,ChunkedWriteHandler
,CompatibleMarshallingDecoder
,DelimiterBasedFrameDecoder
,DiscardClientHandler
,DiscardServerHandler
,EchoClientHandler
,EchoServerHandler
,ExecutionHandler
,FactorialClientHandler
,FactorialServerHandler
,FixedLengthFrameDecoder
,FrameDecoder
,GlobalChannelTrafficShapingHandler
,GlobalTrafficShapingHandler
,HexDumpProxyInboundHandler
,HexDumpProxyInboundHandler.OutboundHandler
,HttpChunkAggregator
,HttpClientCodec
,HttpClientCodec.Decoder
,HttpContentCompressor
,HttpContentDecoder
,HttpContentDecompressor
,HttpContentEncoder
,HttpHelloWorldServerHandler
,HttpMessageDecoder
,HttpRequestDecoder
,HttpResponseDecoder
,HttpServerCodec
,HttpSnoopClientHandler
,HttpSnoopServerHandler
,HttpStaticFileServerHandler
,HttpTunnelingClientSocketChannel.ServletChannelHandler
,HttpTunnelingServlet.OutboundConnectionHandler
,HttpUploadClientHandler
,HttpUploadServerHandler
,IdleStateAwareChannelHandler
,IdleStateAwareChannelUpstreamHandler
,IdleStateHandler
,IpFilteringHandlerImpl
,IpFilterRuleHandler
,LengthFieldBasedFrameDecoder
,LineBasedFrameDecoder
,LocalTimeClientHandler
,LocalTimeServerHandler
,LoggingHandler
,MarshallingDecoder
,ObjectDecoder
,ObjectEchoClientHandler
,ObjectEchoServerHandler
,OneIpFilterHandler
,OneToOneDecoder
,PortUnificationServerHandler
,ProtobufDecoder
,ProtobufVarint32FrameDecoder
,QuoteOfTheMomentClientHandler
,QuoteOfTheMomentServerHandler
,ReadTimeoutHandler
,ReplayingDecoder
,RtspMessageDecoder
,RtspRequestDecoder
,RtspResponseDecoder
,SecureChatClientHandler
,SecureChatServerHandler
,ServerBootstrap.Binder
,SimpleChannelHandler
,SimpleChannelUpstreamHandler
,SocksAuthRequestDecoder
,SocksAuthResponseDecoder
,SocksCmdRequestDecoder
,SocksCmdResponseDecoder
,SocksInitRequestDecoder
,SocksInitResponseDecoder
,SpdyFrameCodec
,SpdyHttpCodec
,SpdyHttpDecoder
,SpdyHttpResponseStreamIdHandler
,SpdyOrHttpChooser
,SpdySessionHandler
,SslHandler
,StringDecoder
,TelnetClientHandler
,TelnetServerHandler
,UptimeClientHandler
,WebSocket00FrameDecoder
,WebSocket07FrameDecoder
,WebSocket08FrameDecoder
,WebSocket13FrameDecoder
,WebSocketClientHandler
,WebSocketFrameAggregator
,WebSocketServerHandler
,WebSocketServerProtocolHandler
,WebSocketServerProtocolHandshakeHandler
,ZlibDecoder
public interface ChannelUpstreamHandler extends ChannelHandler
Handles or intercepts an upstreamChannelEvent
, and sends aChannelEvent
to the next handler in aChannelPipeline
.The most common use case of this interface is to intercept an I/O event generated by I/O workers to transform the received messages or execute the relevant business logic.
SimpleChannelUpstreamHandler
In most cases, you will get to use a
SimpleChannelUpstreamHandler
to implement an upstream handler because it provides an individual handler method for each event type. You might want to implement this interface directly though if you want to handle various types of events in more generic way.Firing an event to the next handler
You can forward the received event upstream or downstream. In most cases,
ChannelUpstreamHandler
will send the event upstream (i.e. inbound) although it is legal to send the event downstream (i.e. outbound):// Sending the event upstream (inbound) void handleUpstream(
ChannelHandlerContext
ctx,ChannelEvent
e) throws Exception { ... ctx.sendUpstream(e); ... } // Sending the event downstream (outbound) void handleDownstream(ChannelHandlerContext
ctx,ChannelEvent
e) throws Exception { ... ctx.sendDownstream(newDownstreamMessageEvent
(...)); ... }Using the helper class to send an event
You will also find various helper methods in
Channels
to be useful to generate and send an artificial or manipulated event.State management
Please refer toChannelHandler
.Thread safety
handleUpstream
will be invoked sequentially by the same thread (i.e. an I/O thread) and therefore a handler does not need to worry about being invoked with a new upstream event before the previous upstream event is finished.This does not necessarily mean that there's a dedicated thread per
Channel
; the I/O thread of some transport can serve more than oneChannel
(e.g. NIO transport), while the I/O thread of other transports can serve only one (e.g. OIO transport).However, if you add an
ExecutionHandler
to aChannelPipeline
, this behavior changes depending on whatExecutor
was employed to dispatch the events. Please refer toExecutionHandler
for more information.
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Nested Class Summary
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Nested classes/interfaces inherited from interface org.jboss.netty.channel.ChannelHandler
ChannelHandler.Sharable
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
handleUpstream(ChannelHandlerContext ctx, ChannelEvent e)
Handles the specified upstream event.
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Method Detail
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handleUpstream
void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e) throws java.lang.Exception
Handles the specified upstream event.- Parameters:
ctx
- the context object for this handlere
- the upstream event to process or intercept- Throws:
java.lang.Exception
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