Create NodeJS standalone process

Question

I'm working on something, using NodeJS, that's intended to run as a service that I can connect with.

Let's say I'm working on a Calculator npm module.

I will need to run it within my repo as following:

./node_modules/.bin/calculator start

And I want to keep it running forever , and i can connect it somehow (on port maybe?)

So, I can send/receive messages with the calculator using another node module, let's say 'calculator-connector', for example as following:

var calcConnector = require('calculator-connector'),
    calc = calcConnector.connect();

calc.add(1, 2);

Any idea how can achieve this design?

Answer 1

I'd make it like this:

Calculator by itself shouldn't be opinionated, where and when it will run. I'd just create it in the moment I need it:

var calculator = require('calculator');
calculator.listen('localhost', 8000); // create the service listening on port 8000
// create client capable of submitting the tasks
calcClient = createCalculatorClient('localhost', 8000) 
calcClient.add(1,2)

I believe that such setup is optimal for quick development and debugging.

When you'll need the things to be really separated (say, calculator itself will run on a separate server), you can do simple node script which'll run the calculator (basically, it's first 2 lines of the snippet above) and then create simple upstart job (in case of debianish server, or some alternative on other platforms), that'll keep the script alive.

PS: check out how express works, it's beautifully designed: http://expressjs.com/

read more about upstart: http://upstart.ubuntu.com/getting-started.html

Answer 2

To run calculator forever, you should use PM2 or Forever .

PM2 allows you to keep applications alive forever, to reload them without downtime and to facilitate common system admin tasks.

For connection, you could create a http or TCP server.