Are processes and messages different?

Yesterday I described the “happened-before” relation. I showed this typical “interaction diagram” illustrating “processes” interacting with “messages”:

message-passing processes

This model of the world proposes two fundamentally different things: “processes” and “messages”. But it’s interesting to try to unify them. Processes in the diagram just look like very slow messages! We could also draw the world this way:

processes and messages

Here, “sending a message” is like “splitting the atom”: what was one becomes many, and the many go their separate ways. “Receiving a message” is like atomic fusion: what were two become one again. There is no distinction in this model between “processes” and “messages”; there are only atoms.

On physical grounds, we could add a “big bang” to this diagram. There’s a clear computing analogy here: process forking! What was one process becomes many, and they follow their own timelines.

processes and messages with big bang

Tagged #concurrency, #computer-science.

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