Hadoop IPC

ODep Monitor uses Hadoop IPC (why? because it's faster and simpler than Java RMI!)

Java RMI (please look at my post on Java RMI)

The problem with Java RMI is permissions, Sun in order to make RMI secure, requires you to grant permissions to the application using 

Below is an interview of Doug Cutting (the creator of Hadoop regarding why they chose to build a custom RPC mechanism instead of choosing RMI)

Also here is a performance comparison between different RPC mechanisms (now you know why I hate XML)

(TO BE POSTED!)

Suggestion: If you are thinking about doing XML RPC, think again, think about Google Protocol Buffers (my post on Google's Protocol Buffer and its performance)