Let's say I have 2 web servers. Both of them just installed Node.js and is running a website (using Express). Pretty basic stuff.

How can Server-A tell Server-B to execute a function? (inside node.js)

Preferably...is there a npm module for this that makes it really easy for me?

Let's say I have 2 web servers. Both of them just installed Node.js and is running a website (using Express). Pretty basic stuff.

How can Server-A tell Server-B to execute a function? (inside node.js)

Preferably...is there a npm module for this that makes it really easy for me?

• javascript
• node.js
• ipc
• rpc

4 Answers 4

How can Server-A tell Server-B to execute a function?

You can use one of the RPC modules, for example dnode.

Check out Wildcard API, it's an RPC implementation for JavaScript.

It works between the browser and a Node.js server and also works between multiple Node.js processes:

// Node.js process 1

const express = require('express');
const wildcardMiddleware = require('@wildcard-api/server/express');
const {endpoints} = require('@wildcard-api/server');

endpoints.hello = async function() {
  const msg = 'Hello from process 1';
  return msg;
};

const app = express();
app.use(wildcardMiddleware());

app.listen(3000);

// Node.js process 2

const wildcard = require('@wildcard-api/client');
const {endpoints} = require('@wildcard-api/client');

wildcard.serverUrl = 'http://localhost:3000';

(async () => {
  const msg = await endpoints.hello();
  console.log(msg); // Prints "Hello from process 1"
})();

You can browse the code of the example here.

You most likely want something like a JSON-RPC module for Node. After some quick searching, here is a JSON-RPC middleware module for Connect that would be perfect to use with Express.

Also, this one looks promising too.

Update : The library I've made & linked below, isn't maintained currently. Please check out the other answers on this thread.

What you need is called RPC. It is possible to build your own, but depending on the features you need, it can be time consuming.

Given the amount of time I had to invest, I'd recommend finding a decent library that suits your purpose, instead of hand rolling. My usecase required additional complex features like selective RPC calls, for which I couldn't find anything lightweight enough, so had to roll my own.

Here it is https://github.com/DhavalW/octopus.