com.hazelcast.internal.networking

Interface ChannelInboundHandler

All Known Implementing Classes:

ChannelInboundHandlerWithCounters, ClientMessageChannelInboundHandler, MemberChannelInboundHandler, TextChannelInboundHandler

public interface ChannelInboundHandler

The ChannelInboundHandler provides control when data is received and needs to be processed. For example data has received on the socket and needs to be decoded into a Packet. ChannelInboundHandler are not expected to be thread-safe; each channel will gets its own instance(s). A ChannelInboundHandler is constructed through a ChannelInitializer.

Pipelining & Encryption

The ChannelInboundHandler/ChannelOutboundHandler can also form a pipeline. For example for SSL there could be a initial ChannelInboundHandler that decryption the ByteBuffer and passes the decrypted ByteBuffer to the next ChannelInboundHandler; which could be a MemberChannelInboundHandler that reads out any Packet from the decrypted ByteBuffer. Using this approach encryption can easily be added to any type of communication, not only member 2 member communication. Currently security is added by using a Channel, but this is not needed if the handlers form a pipeline. Netty follows a similar approach with pipelining and adding encryption. There is no explicit support for setting up a 'pipeline' of ChannelInboundHandler/WriterHandlers but t can easily be realized by setting up the chain and let a handler explicitly forward to the next. Since it isn't a common practice for the handler so far, isn't needed to add additional complexity to the system; just set up a chain manually. pseudo code:

     public class DecryptingReadHandler implements ChannelInboundHandler {
         private final ChannelInboundHandler next;

         public DecryptingReadHandler(ChannelInboundHandler next) {
             this.next = next;
         }

         public void onRead(ByteBuffer src) {
             decrypt(src, decryptedSrc);
             next.onRead(decryptedSrc)
         }
     }
 

The next ChannelInboundHandler is the next item in the pipeline. For encryption is similar approach can be followed where the DecryptingWriteHandler is the last ChannelOutboundHandler in the pipeline.

See Also:

ChannelOutboundHandler, EventLoopGroup, ChannelInitializer, ChannelErrorHandler, Channel

Method Summary

Modifier and Type	Method and Description
void	onRead(ByteBuffer src) A callback to indicate that data is available in the src ByteBuffer to be processed.

Method Detail

onRead

void onRead(ByteBuffer src)
     throws Exception

A callback to indicate that data is available in the src ByteBuffer to be processed.

Parameters:

src - the ByteBuffer containing the data to read. The ByteBuffer is already in reading mode and when completed, should not be converted to write-mode using clear/compact.

Throws:

Exception - if something fails while reading data from the ByteBuffer or processing the data (e.g. when a Packet fails to get processed). When an exception is thrown, the ChannelErrorHandler is called.