Node.js 和 Java 之间的 IPC 通信

Question

I'm looking to communicate between Node.js and a Java sub-process via IPC. I'm looking for recommendations that do not require opening a port.

const { spawn } = require('child_process')

// Java App is within args
const args = []

const javaProcess = spawn('java', args, { cwd: __dirname })

javaProcess.on('message', (m) => {
  console.log('PARENT got message:', m)
})

// Sends { 'hello': 'world' } to the Java process
javaProcess.send({ hello: 'world' })

I understand that the Node layer can send messages to a sub-process, I just don't know how I'd go about listening for messages in the Java layer and sending messages back.

Any help is greatly appreciated, thanks!

Answer 1

I ended up solving this with inspiration from Erwin Bolwidt's Comment .

const { spawn } = require('child_process')

// Java App is within args
const args = []

const javaProcess = spawn('java', args, { cwd: __dirname })

javaProcess.stdout.on('data', (m) => {
  console.log('PARENT got message:', m)
})

// Sends message to the Java process
javaProcess.stdin.write('Hello there java!');

The java process can wait for a message with a Scanner on System.in then print output to System.out .

In summary you're just rerouting the process's stdin/stdout. https://nodejs.org/api/child_process.html#subprocessstdout

Answer 2

I solved this issue by using named pipes...

On Node I used the Net API https://nodejs.org/api/net.html#net_ipc_support

On Java I used RandomAccessFile https://docs.oracle.com/javase/7/docs/api/java/io/RandomAccessFile.html