Integrating Node Js and Rust for a long running monitor application

This is a proof of concept to see how a NodeJS parent application could pipe an infinite stream of data from a Rust process which pretends to be a conduit for data from a serial device.

Requirements

• The solution must work on Windows and Unix OSes.
• The child process must continuously stream data to the parent until signaled to stop.
• The parent process must not block it's main thread while data is being received.
• The parent process must be able to signal the child process to stop, cleanly.

Solution

Everything can be achieved using stdio streams, and piping between parent and child.

Using NodeJS's child_process.spawn allows for streaming of data from the child asynchronously. The main thread does not get blocked.

Signaling the child process to stop can be done trivially by closing the child process's stdin stream within the parent (child.stdin.end()).

After starting up a thread streaming data back to the parent, the child process blocks on a read to it's stdin. When the stream receives the EOF (End Of File) marker, it shuts down. When the parent process closes the stream this sends EOF to the child, triggering a clean shutdown procedure.

Running

• Install Rust 1.25 or later
• Install NodeJS 10+

Then:

$ cargo build && node main.js

Example output:

(parent: main thread ended)
from child: "Pretend serial output 0"
from child: "Pretend serial output 1"
from child: "Pretend serial output 2"
from child: "Pretend serial output 3"
from child: "Pretend serial output 4"
from child: "Pretend serial output 5"
from child: "Pretend serial output 6"
from child: "Pretend serial output 7"
from child: "Pretend serial output 8"
from child: "Pretend serial output 9"
(parent: closing child process stdin)
from child: "(rust: Got EOF)
(rust: sending stop message)
(rust: waiting for service stop ...)"
child process exited with code 0