Erlang Mantra

Origin: Making Reliable Distributed Systems in the Presence of Software Errors

• Everything is a process.
• Processes are strongly isolated.
• Process creation and destruction is a lightweight operation.
• Message passing is the only way for processes to interact.
• Processes have unique names.
• If you know the name of a process you can send it a message.
• Processes share no resources.
• Error handling is non-local.
• Processes do what they are supposed to do or fail.

...The statement about error handling is perhaps less obvious. When we make a fault-tolerant system we need at least two physically separated computers. Using a single computer will not work, if it crashes, all is lost. The simplest fault-tolerant system we can imagine has exactly two computers, if one computer crashes, then the other computer should take over what the first computer was doing. In this simple situation even the sodware for fault-recovery must be non-local; the error occurs on the first machine, but is corrected by sodware running on the second machine.