Domains Module Example

domains.js

var fs = require('fs'), domain = require('domain')
console.log("\n\n\n\n\n\nHello, welcome to a domain example\n")
// We create three domains, two of which have their own error handler
var d1 = domain.create(), d2 = domain.create(), d3 = domain.create();
[d1,d2].forEach(function(domain, i){
	domain.i = i
	domain.on('error', function(err) {
		console.error("Domain "+err.domain.i+" has a problem!:\n ", err.message)
		console.error("We've dealt with the problem\n")
}) })
// Toss a ENOENT to d1
fs.readFile("does-not-exist.txt", "utf8", d1.intercept(function(data){
	console.log("We read a file") // except it didn't exist
}))
// Toss an Error to d2
var interval = setInterval(function(){
	throw new Error("Interval error")
}, 600)
d2.add(interval);
// All domains throw an error- the third fails!
[d1, d2, d3].forEach(function(domain, i){
	domain.run(function(){
		setTimeout(function(){
			throw new Error("Domain"+(i+1)+" misbehaves")
		}, 1000*(i+1))
}) })

output.txt

Hello, welcome to a domain example

Domain 1 has a problem!:
  ENOENT, open 'does-not-exist.txt'
We've dealt with the problem

Domain 2 has a problem!:
  Interval error
We've dealt with the problem

Domain 1 has a problem!:
  Domain1 misbehaves
We've dealt with the problem

Domain 2 has a problem!:
  Domain2 misbehaves
We've dealt with the problem


/Users/Guest/sample.js:26
			throw new Error("Domain"+(i+1)+" misbehaves")
			      ^
Error: Domain3 misbehaves
    at null._onTimeout (/Users/Guest/sample.js:26:10)
    at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)