Interface Channel
-
- All Superinterfaces:
AttributeMap,ChannelOutboundInvoker,java.lang.Comparable<Channel>
- All Known Subinterfaces:
DatagramChannel,DomainDatagramChannel,DomainSocketChannel,DuplexChannel,Http2StreamChannel,QuicChannel,QuicStreamChannel,SctpChannel,SctpServerChannel,ServerChannel,ServerDomainSocketChannel,ServerSocketChannel,SocketChannel,UdtChannel,UdtServerChannel,UnixChannel
- All Known Implementing Classes:
AbstractChannel,AbstractEpollServerChannel,AbstractEpollStreamChannel,AbstractKQueueServerChannel,AbstractKQueueStreamChannel,AbstractNioByteChannel,AbstractNioChannel,AbstractNioMessageChannel,AbstractOioByteChannel,AbstractOioChannel,AbstractOioMessageChannel,AbstractServerChannel,EmbeddedChannel,EpollDatagramChannel,EpollDomainDatagramChannel,EpollDomainSocketChannel,EpollServerDomainSocketChannel,EpollServerSocketChannel,EpollSocketChannel,IoUringDatagramChannel,IoUringDomainSocketChannel,IoUringServerDomainSocketChannel,IoUringServerSocketChannel,IoUringSocketChannel,KQueueDatagramChannel,KQueueDomainDatagramChannel,KQueueDomainSocketChannel,KQueueServerDomainSocketChannel,KQueueServerSocketChannel,KQueueSocketChannel,LocalChannel,LocalServerChannel,NioDatagramChannel,NioDomainSocketChannel,NioSctpChannel,NioSctpServerChannel,NioServerDomainSocketChannel,NioServerSocketChannel,NioSocketChannel,NioUdtAcceptorChannel,NioUdtByteAcceptorChannel,NioUdtByteConnectorChannel,NioUdtByteRendezvousChannel,NioUdtMessageAcceptorChannel,NioUdtMessageConnectorChannel,NioUdtMessageRendezvousChannel,OioByteStreamChannel,OioDatagramChannel,OioSctpChannel,OioSctpServerChannel,OioServerSocketChannel,OioSocketChannel,RxtxChannel
public interface Channel extends AttributeMap, ChannelOutboundInvoker, java.lang.Comparable<Channel>
A nexus to a network socket or a component which is capable of I/O operations such as read, write, connect, and bind.A channel provides a user:
- the current state of the channel (e.g. is it open? is it connected?),
- the configuration parameters of the channel (e.g. receive buffer size),
- the I/O operations that the channel supports (e.g. read, write, connect, and bind), and
- the
ChannelPipelinewhich handles all I/O events and requests associated with the channel.
All I/O operations are asynchronous.
All I/O operations in Netty are asynchronous. It means any I/O calls will return immediately with no guarantee that the requested I/O operation has been completed at the end of the call. Instead, you will be returned with a
ChannelFutureinstance which will notify you when the requested I/O operation has succeeded, failed, or canceled.Channels are hierarchical
A
Channelcan have a parent depending on how it was created. For instance, aSocketChannel, that was accepted byServerSocketChannel, will return theServerSocketChannelas its parent onparent().The semantics of the hierarchical structure depends on the transport implementation where the
Channelbelongs to. For example, you could write a newChannelimplementation that creates the sub-channels that share one socket connection, as BEEP and SSH do.Downcast to access transport-specific operations
Some transports exposes additional operations that is specific to the transport. Down-cast the
Channelto sub-type to invoke such operations. For example, with the old I/O datagram transport, multicast join / leave operations are provided byDatagramChannel.Release resources
It is important to call
close()orclose(ChannelPromise)to release all resources once you are done with theChannel. This ensures all resources are released in a proper way, i.e. filehandles.
-
-
Nested Class Summary
Nested Classes Modifier and Type Interface Description static interfaceChannel.UnsafeUnsafe operations that should never be called from user-code.
-
Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description default ByteBufAllocatoralloc()Return the assignedByteBufAllocatorwhich will be used to allocateByteBufs.default ChannelFuturebind(java.net.SocketAddress localAddress)Request to bind to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFuturebind(java.net.SocketAddress localAddress, ChannelPromise promise)Request to bind to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default longbytesBeforeUnwritable()Get how many bytes can be written untilisWritable()returnsfalse.default longbytesBeforeWritable()Get how many bytes must be drained from underlying buffers untilisWritable()returnstrue.default ChannelFutureclose()Request to close theChanneland notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFutureclose(ChannelPromise promise)Request to close theChanneland notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.ChannelFuturecloseFuture()Returns theChannelFuturewhich will be notified when this channel is closed.ChannelConfigconfig()Returns the configuration of this channel.default ChannelFutureconnect(java.net.SocketAddress remoteAddress)Request to connect to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFutureconnect(java.net.SocketAddress remoteAddress, ChannelPromise promise)Request to connect to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFutureconnect(java.net.SocketAddress remoteAddress, java.net.SocketAddress localAddress)Request to connect to the givenSocketAddresswhile bind to the localAddress and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFutureconnect(java.net.SocketAddress remoteAddress, java.net.SocketAddress localAddress, ChannelPromise promise)Request to connect to the givenSocketAddresswhile bind to the localAddress and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFuturederegister()Request to deregister from the previous assignedEventExecutorand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFuturederegister(ChannelPromise promise)Request to deregister from the previous assignedEventExecutorand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFuturedisconnect()Request to disconnect from the remote peer and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.default ChannelFuturedisconnect(ChannelPromise promise)Request to disconnect from the remote peer and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.EventLoopeventLoop()default Channelflush()Request to flush all pending messages via this ChannelOutboundInvoker.default <T> TgetOption(ChannelOption<T> option)Return the value of the givenChannelOptionChannelIdid()Returns the globally unique identifier of thisChannel.booleanisActive()Returntrueif theChannelis active and so connected.booleanisOpen()Returnstrueif theChannelis open and may get active laterbooleanisRegistered()default booleanisWritable()Returnstrueif and only if the I/O thread will perform the requested write operation immediately.java.net.SocketAddresslocalAddress()Returns the local address where this channel is bound to.ChannelMetadatametadata()default ChannelFuturenewFailedFuture(java.lang.Throwable cause)Create a newChannelFuturewhich is marked as failed already.default ChannelProgressivePromisenewProgressivePromise()Return an newChannelProgressivePromisedefault ChannelPromisenewPromise()Return a newChannelPromise.default ChannelFuturenewSucceededFuture()Create a newChannelFuturewhich is marked as succeeded already.Channelparent()Returns the parent of this channel.ChannelPipelinepipeline()Return the assignedChannelPipeline.default Channelread()Request to Read data from theChannelinto the first inbound buffer, triggers anChannelInboundHandler.channelRead(ChannelHandlerContext, Object)event if data was read, and triggers achannelReadCompleteevent so the handler can decide to continue reading.java.net.SocketAddressremoteAddress()Returns the remote address where this channel is connected to.default <T> booleansetOption(ChannelOption<T> option, T value)Sets a configuration property with the specified name and value.Channel.Unsafeunsafe()Returns an internal-use-only object that provides unsafe operations.default ChannelPromisevoidPromise()Return a special ChannelPromise which can be reused for different operations.default ChannelFuturewrite(java.lang.Object msg)Request to write a message via thisChannelHandlerContextthrough theChannelPipeline.default ChannelFuturewrite(java.lang.Object msg, ChannelPromise promise)Request to write a message via thisChannelHandlerContextthrough theChannelPipeline.default ChannelFuturewriteAndFlush(java.lang.Object msg)Shortcut for callChannelOutboundInvoker.write(Object)andChannelOutboundInvoker.flush().default ChannelFuturewriteAndFlush(java.lang.Object msg, ChannelPromise promise)Shortcut for callChannelOutboundInvoker.write(Object, ChannelPromise)andChannelOutboundInvoker.flush().-
Methods inherited from interface io.netty.util.AttributeMap
attr, hasAttr
-
-
-
-
Method Detail
-
eventLoop
EventLoop eventLoop()
-
parent
Channel parent()
Returns the parent of this channel.- Returns:
- the parent channel.
nullif this channel does not have a parent channel.
-
config
ChannelConfig config()
Returns the configuration of this channel.
-
isOpen
boolean isOpen()
Returnstrueif theChannelis open and may get active later
-
isRegistered
boolean isRegistered()
-
isActive
boolean isActive()
Returntrueif theChannelis active and so connected.
-
metadata
ChannelMetadata metadata()
-
localAddress
java.net.SocketAddress localAddress()
Returns the local address where this channel is bound to. The returnedSocketAddressis supposed to be down-cast into more concrete type such asInetSocketAddressto retrieve the detailed information.- Returns:
- the local address of this channel.
nullif this channel is not bound.
-
remoteAddress
java.net.SocketAddress remoteAddress()
Returns the remote address where this channel is connected to. The returnedSocketAddressis supposed to be down-cast into more concrete type such asInetSocketAddressto retrieve the detailed information.- Returns:
- the remote address of this channel.
nullif this channel is not connected. If this channel is not connected but it can receive messages from arbitrary remote addresses (e.g.DatagramChannel, useDefaultAddressedEnvelope.recipient()to determine the origination of the received message as this method will returnnull.
-
closeFuture
ChannelFuture closeFuture()
Returns theChannelFuturewhich will be notified when this channel is closed. This method always returns the same future instance.
-
isWritable
default boolean isWritable()
Returnstrueif and only if the I/O thread will perform the requested write operation immediately. Any write requests made when this method returnsfalseare queued until the I/O thread is ready to process the queued write requests.WriteBufferWaterMarkcan be used to configure on which condition the write buffer would cause this channel to change writability.
-
bytesBeforeUnwritable
default long bytesBeforeUnwritable()
Get how many bytes can be written untilisWritable()returnsfalse. This quantity will always be non-negative. IfisWritable()isfalsethen 0.WriteBufferWaterMarkcan be used to define writability settings.
-
bytesBeforeWritable
default long bytesBeforeWritable()
Get how many bytes must be drained from underlying buffers untilisWritable()returnstrue. This quantity will always be non-negative. IfisWritable()istruethen 0.WriteBufferWaterMarkcan be used to define writability settings.
-
unsafe
Channel.Unsafe unsafe()
Returns an internal-use-only object that provides unsafe operations.
-
pipeline
ChannelPipeline pipeline()
Return the assignedChannelPipeline.
-
alloc
default ByteBufAllocator alloc()
Return the assignedByteBufAllocatorwhich will be used to allocateByteBufs.
-
getOption
default <T> T getOption(ChannelOption<T> option)
Return the value of the givenChannelOption
-
setOption
default <T> boolean setOption(ChannelOption<T> option, T value)
Sets a configuration property with the specified name and value. To override this method properly, you must call the super class:public boolean setOption(ChannelOption<T> option, T value) { if (super.setOption(option, value)) { return true; } if (option.equals(additionalOption)) { .... return true; } return false; }- Returns:
trueif and only if the property has been set
-
read
default Channel read()
Description copied from interface:ChannelOutboundInvokerRequest to Read data from theChannelinto the first inbound buffer, triggers anChannelInboundHandler.channelRead(ChannelHandlerContext, Object)event if data was read, and triggers achannelReadCompleteevent so the handler can decide to continue reading. If there's a pending read operation already, this method does nothing.This will result in having the
ChannelOutboundHandler.read(ChannelHandlerContext)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
readin interfaceChannelOutboundInvoker
-
flush
default Channel flush()
Description copied from interface:ChannelOutboundInvokerRequest to flush all pending messages via this ChannelOutboundInvoker.- Specified by:
flushin interfaceChannelOutboundInvoker
-
writeAndFlush
default ChannelFuture writeAndFlush(java.lang.Object msg)
Description copied from interface:ChannelOutboundInvokerShortcut for callChannelOutboundInvoker.write(Object)andChannelOutboundInvoker.flush().- Specified by:
writeAndFlushin interfaceChannelOutboundInvoker
-
writeAndFlush
default ChannelFuture writeAndFlush(java.lang.Object msg, ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerShortcut for callChannelOutboundInvoker.write(Object, ChannelPromise)andChannelOutboundInvoker.flush().- Specified by:
writeAndFlushin interfaceChannelOutboundInvoker
-
write
default ChannelFuture write(java.lang.Object msg, ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to write a message via thisChannelHandlerContextthrough theChannelPipeline. This method will not request to actual flush, so be sure to callChannelOutboundInvoker.flush()once you want to request to flush all pending data to the actual transport.- Specified by:
writein interfaceChannelOutboundInvoker
-
write
default ChannelFuture write(java.lang.Object msg)
Description copied from interface:ChannelOutboundInvokerRequest to write a message via thisChannelHandlerContextthrough theChannelPipeline. This method will not request to actual flush, so be sure to callChannelOutboundInvoker.flush()once you want to request to flush all pending data to the actual transport.- Specified by:
writein interfaceChannelOutboundInvoker
-
deregister
default ChannelFuture deregister(ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to deregister from the previous assignedEventExecutorand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. The givenChannelPromisewill be notified.This will result in having the
ChannelOutboundHandler.deregister(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
deregisterin interfaceChannelOutboundInvoker
-
close
default ChannelFuture close(ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to close theChanneland notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. After it is closed it is not possible to reuse it again. The givenChannelPromisewill be notified.This will result in having the
ChannelOutboundHandler.close(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
closein interfaceChannelOutboundInvoker
-
disconnect
default ChannelFuture disconnect(ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to disconnect from the remote peer and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. The givenChannelPromisewill be notified.This will result in having the
ChannelOutboundHandler.disconnect(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
disconnectin interfaceChannelOutboundInvoker
-
connect
default ChannelFuture connect(java.net.SocketAddress remoteAddress, java.net.SocketAddress localAddress, ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to connect to the givenSocketAddresswhile bind to the localAddress and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. The givenChannelPromisewill be notified and also returned.This will result in having the
ChannelOutboundHandler.connect(ChannelHandlerContext, SocketAddress, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
connectin interfaceChannelOutboundInvoker
-
connect
default ChannelFuture connect(java.net.SocketAddress remoteAddress, ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to connect to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. The givenChannelFuturewill be notified.If the connection fails because of a connection timeout, the
ChannelFuturewill get failed with aConnectTimeoutException. If it fails because of connection refused aConnectExceptionwill be used.This will result in having the
ChannelOutboundHandler.connect(ChannelHandlerContext, SocketAddress, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
connectin interfaceChannelOutboundInvoker
-
bind
default ChannelFuture bind(java.net.SocketAddress localAddress, ChannelPromise promise)
Description copied from interface:ChannelOutboundInvokerRequest to bind to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. The givenChannelPromisewill be notified.This will result in having the
ChannelOutboundHandler.bind(ChannelHandlerContext, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
bindin interfaceChannelOutboundInvoker
-
deregister
default ChannelFuture deregister()
Description copied from interface:ChannelOutboundInvokerRequest to deregister from the previous assignedEventExecutorand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.This will result in having the
ChannelOutboundHandler.deregister(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
deregisterin interfaceChannelOutboundInvoker
-
close
default ChannelFuture close()
Description copied from interface:ChannelOutboundInvokerRequest to close theChanneland notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error. After it is closed it is not possible to reuse it again.This will result in having the
ChannelOutboundHandler.close(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
closein interfaceChannelOutboundInvoker
-
disconnect
default ChannelFuture disconnect()
Description copied from interface:ChannelOutboundInvokerRequest to disconnect from the remote peer and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.This will result in having the
ChannelOutboundHandler.disconnect(ChannelHandlerContext, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
disconnectin interfaceChannelOutboundInvoker
-
connect
default ChannelFuture connect(java.net.SocketAddress remoteAddress, java.net.SocketAddress localAddress)
Description copied from interface:ChannelOutboundInvokerRequest to connect to the givenSocketAddresswhile bind to the localAddress and notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.This will result in having the
ChannelOutboundHandler.connect(ChannelHandlerContext, SocketAddress, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
connectin interfaceChannelOutboundInvoker
-
connect
default ChannelFuture connect(java.net.SocketAddress remoteAddress)
Description copied from interface:ChannelOutboundInvokerRequest to connect to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.If the connection fails because of a connection timeout, the
ChannelFuturewill get failed with aConnectTimeoutException. If it fails because of connection refused aConnectExceptionwill be used.This will result in having the
ChannelOutboundHandler.connect(ChannelHandlerContext, SocketAddress, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
connectin interfaceChannelOutboundInvoker
-
bind
default ChannelFuture bind(java.net.SocketAddress localAddress)
Description copied from interface:ChannelOutboundInvokerRequest to bind to the givenSocketAddressand notify theChannelFutureonce the operation completes, either because the operation was successful or because of an error.This will result in having the
ChannelOutboundHandler.bind(ChannelHandlerContext, SocketAddress, ChannelPromise)method called of the nextChannelOutboundHandlercontained in theChannelPipelineof theChannel.- Specified by:
bindin interfaceChannelOutboundInvoker
-
newPromise
default ChannelPromise newPromise()
Description copied from interface:ChannelOutboundInvokerReturn a newChannelPromise.- Specified by:
newPromisein interfaceChannelOutboundInvoker
-
newProgressivePromise
default ChannelProgressivePromise newProgressivePromise()
Description copied from interface:ChannelOutboundInvokerReturn an newChannelProgressivePromise- Specified by:
newProgressivePromisein interfaceChannelOutboundInvoker
-
newSucceededFuture
default ChannelFuture newSucceededFuture()
Description copied from interface:ChannelOutboundInvokerCreate a newChannelFuturewhich is marked as succeeded already. SoFuture.isSuccess()will returntrue. AllFutureListeneradded to it will be notified directly. Also every call of blocking methods will just return without blocking.- Specified by:
newSucceededFuturein interfaceChannelOutboundInvoker
-
newFailedFuture
default ChannelFuture newFailedFuture(java.lang.Throwable cause)
Description copied from interface:ChannelOutboundInvokerCreate a newChannelFuturewhich is marked as failed already. SoFuture.isSuccess()will returnfalse. AllFutureListeneradded to it will be notified directly. Also every call of blocking methods will just return without blocking.- Specified by:
newFailedFuturein interfaceChannelOutboundInvoker
-
voidPromise
default ChannelPromise voidPromise()
Description copied from interface:ChannelOutboundInvokerReturn a special ChannelPromise which can be reused for different operations.It's only supported to use it for
ChannelOutboundInvoker.write(Object, ChannelPromise).Be aware that the returned
Be aware this is an expert feature and should be used with care!ChannelPromisewill not support most operations and should only be used if you want to save an object allocation for every write operation. You will not be able to detect if the operation was complete, only if it failed as the implementation will callChannelPipeline.fireExceptionCaught(Throwable)in this case.- Specified by:
voidPromisein interfaceChannelOutboundInvoker
-
-