com.hazelcast.internal.networking

Interface ReadHandler

All Known Implementing Classes:

ClientMessageReadHandler, ClientReadHandler, MemberReadHandler, TextReadHandler

public interface ReadHandler

Reads content from a ByteBuffer and processes it. The ReadHandler is invoked by the SocketReader after it has read data from the socket. A typical example is that Packet instances are created from the buffered data and handing them over the the PacketDispatcher. See MemberReadHandler for more information. Each SocketReader will have its own ReadHandler instance. Therefor it doesn't need to be thread-safe.

Pipelining & Encryption

The ReadHandler/WriteHandler can also form a pipeline. For example for SSL there could be a initial ReadHandler that decryption the ByteBuffer and passes the decrypted ByteBuffer to the next ReadHandler; which could be a MemberReadHandler 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 SocketChannelWrapper, 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 ReadHandler/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 ReadHandler {
         private final ReadHandler next;

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

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

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

See Also:

WriteHandler, SocketReader, TcpIpConnection, IOThreadingModel

Method Summary

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

Method Detail

onRead

void onRead(ByteBuffer src)
     throws Exception

A callback to indicate that data is available in the 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. That is a task of the SocketReader.

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 TcpIpConnection is closed. There is no point continuing with a potentially corrupted stream.