Dubbo network communication source code reading notes

Analysis of dubbo network communication layer protocol.

It starts with com.alibaba.dubbo.remoting.transport.netty.NettyServer listening to tcp

Then dubbo encapsulates the ByteBuffer into a subclass of ChannelBufferInputStream  InputStream

com.alibaba.dubbo.rpc.protocol.dubbo.DubboCodec#decodeBody

Start protocol parsing

int readable = buffer.readableBytes();
byte[] header = new byte[Math.min(readable, HEADER_LENGTH)];
buffer.readBytes(header);

The first 16 bytes are header information

if (readable > 0 && header[0] != MAGIC_HIGH 
|| readable > 1 && header[1] != MAGIC_LOW)

int len = Bytes.bytes2int(header, 12);

long id = Bytes.bytes2long(header, 4);

byte flag = header[2], proto = (byte) (flag & SERIALIZATION_MASK);
Serialization s = CodecSupport.getSerialization(channel.getUrl(), proto);

 The flag is used to determine the protocol, and choose which serialization to use

dubbo is serialized with Hessian2Serialization

status is used to identify success or failure

 

finally to

com.alibaba.dubbo.rpc.protocol.dubbo.DecodeableRpcInvocation#decode(com.alibaba.dubbo.remoting.Channel, java.io.InputStream) to specifically parse the object

setAttachment(Constants.DUBBO_VERSION_KEY, in.readUTF());
setAttachment(Constants.PATH_KEY, in.readUTF());
setAttachment(Constants.VERSION_KEY, in.readUTF());

Set the relevant value

 

com.alibaba.com.caucho.hessian.io.Hessian2Input # readObject ()

This method can see how dubbo parses a specific object from the bytes.

 

 

There will be time for a more in-depth analysis later.