different modes of inter process communication

[B. X.]

greetings,

   Is there a summary somewhere regarding the different APIs used
between JVM processes in Hadoop to communicate with each other?  I
found at least the following:
-  using SocketChannel with apache/hadoop/ipc/[Server|Client] apis;
-  using IO streams customized in
apache/hadoop/hdfs/server/datanode/Block[Sender|Receiver];

Thanks,
-Bin