zmq-json-pub.js

A node.js module for publishing JSON messages via 0MQ (ZeroMQ)

Install 0MQ

On a Mac:

$ brew install zmq

To verify the installation

$ man zmq

See zeromq.org

Install zmq-json-pub in your project

$ npm init
$ npm install zmq-json-pub --save

Usage

The complete project can be found in the examples/demo folder.

This example shows how to create a simple app that publishes a heartbeat JSON message every 3 seconds. The example JSON is completely arbitrary. You can specify your own JSON format.

File: examples/demo/config.js

var config = {};
config.endpoint = "tcp://*:5431";
config.interval = 3000;    // micro seconds
module.exports = config;

File: examples/demo/index.js

"use strict";

var ZmqJsonPub = require('zmq-json-pub'),
	config = require('./config'),
	pub = new ZmqJsonPub();

pub.publish(config.endpoint);

let data = {
	type: "heartbeat",
	status: "OK",
	message: 'service is running',
	timestamp: Date.now()
}

function heartbeat() {
	data.timestamp = Date.now();
	console.log("sending heartbeat at " + new Date(data.timestamp));
	pub.send(data, function(err) {
    	if (err) {
        	console.log(err);
        	return;
    	}
	}); 
	setTimeout(heartbeat, config.interval); 
}

console.log("Sending heartbeat every " + config.interval / 1000 + " seconds")

setTimeout(heartbeat, config.interval);

/*
	Handle termination can close pub.
*/

//  terminator === the termination handler.
function terminator(sig) {
	if (typeof sig === "string") {
		console.log('%s: Received %s - terminating Node server ...',
        	Date(Date.now()), sig);
  		console.log("Closing publisher before exit");
  		pub.close();
  		process.exit(1);
	}
	console.log('%s: Node server stopped.', Date(Date.now()) );
}

//  Process on exit and signals.
process.on('exit', function() { terminator(); });

['SIGHUP', 'SIGINT', 'SIGQUIT', 'SIGILL', 'SIGTRAP', 'SIGABRT', 'SIGBUS',
 'SIGFPE', 'SIGUSR1', 'SIGSEGV', 'SIGUSR2', 'SIGPIPE', 'SIGTERM'
].forEach(function(element, index, array) {
	process.on(element, function() { terminator(element); });
});

To run:

$ node index.js

To stop press Ctrl-C.

Tests

Tests assume that mocha has been installed globally. If not execute the following:

$ npm install -g mocha

Run the tests from the projects root folder in one of the following ways:

$ mocha --recursive --timeout 20000

Or

$ npm test

Or if you feel like kickin' it old skool:

make test

Testing by Version

To run the tests for each version (currently there is only one version (v0001)):

$ mocha --timeout 5000 --recursive test/v0001/*test.js

The tests generate log files in a logs/ folder under the projects root folder.

Repo(s)

• bitbucket.org/mitchallen/zmq-json-pub.git

Contributing

In lieu of a formal style guide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.

Version History

Version 0.1.2 release notes

• Wrapped send call in setTimeout
• Added sendDelay property (in micro seconds)

Version 0.1.1 release notes

• Updated example to use published module

Version 0.1.0 release notes

• Initial release