Erlang / Erlang Advanced Interview questions

What is rpc:call/4 and how does it work across distributed nodes?

rpc:call(Node, Module, Function, Args) lets one node synchronously invoke a function on another connected node and get the result back, wrapping the underlying message-passing machinery so it looks like an ordinary function call.

Result = rpc:call('nodeb@host', lists, sort, [[3,1,2]]).
%% Result = [1,2,3], computed on nodeb and returned to the caller

Under the hood, the local rpc server sends a request to its counterpart on the remote node, which spawns a process to execute Module:Function(Args) there and sends the result back; the caller blocks (with an optional timeout) waiting for that reply, similar in spirit to gen_server:call but targeting an arbitrary function rather than a specific process's callback. Because it executes arbitrary code on the remote node, it inherits the same trust model as the rest of distributed Erlang — any connected, cookie-authenticated node can run arbitrary functions on any other.

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What does rpc:call(Node, Mod, Fun, Args) let you do? Only send an asynchronous message to Node

✗ Not quite. Try again.

Synchronously invoke Mod:Fun(Args) on a remote node and get the result back

✓ Correct! Well done.

✗ Not quite. Try again.

What trust assumption does rpc:call rely on? It requires no trust since it only reads data

✗ Not quite. Try again.

The same cookie-based trust model as the rest of distributed Erlang, since it executes arbitrary remote code

✓ Correct! Well done.

It only works between nodes on the same physical machine

✗ Not quite. Try again.

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Erlang / Erlang Advanced Interview questions

What is rpc:call/4 and how does it work across distributed nodes?

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