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:rex process

As explained in Elixir in Action, Third Edition

:rex is a locally registered Erlang kernel process that receives and executes remote procedure call requests.

:rex is a locally registered Erlang kernel process that underpins remote procedure calls. An RPC request sends an MFA tuple to the target node’s :rex process; :rex invokes apply/3 and returns the result. section 12.1.5

This makes message passing the core distribution primitive: services such as :rpc communicate with processes registered locally on remote nodes rather than requiring a separate transport abstraction. section 12.1.5

iex(node1@localhost)1> :rpc.call(:node2@localhost, Kernel, :abs, [-1])
1

Observe a remote Kernel.abs/1 call through the :rpc interface. section 12.1.5

How Elixir in Action, Third Edition covers it

How deep it goes
Traces RPC from message delivery to apply/3 and response, while deferring implementation details in rpc.erl.
Examples
Demonstrates :rpc.call/4 invoking Kernel.abs/1 on a remote node.
What it assumes
Assumes connected Erlang nodes and familiarity with MFA tuples, registered processes, and message passing.
What you can do after
Evaluate remote functions through :rpc.call/4 across connected Erlang nodes.
How it connects
Connects Erlang distribution, RPC, message passing, local process registration, MFA, and apply/3.
Cover of Elixir in Action, Third Edition
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This explainer was generated by Manning's knowledge graph from the text of Elixir in Action, Third Edition. The section links point to the parts of the book it draws on.