Gallop

Gallop polls REST APIs at particular intervals to listen for changes.

Installation

Gallop is available on the NPM registry.

npm install gallop

Usage

var gallop = require('gallop')({
  interval: 10
});

// Add a target.
gallop.subscribe('//api-endpoint.provider.com/api', null, function(err, result, httpResponse){
  if(err){
    return console.error(err);
  }
  console.log(result);
})

// Start listening.
gallop.start();

Documentation

Gallop

Requiring Gallop exposes a Gallop constructor. This object serves as a daemon which listens to requests in the background. Arguments:

• options -- An optional options object with keys:
  • interval -- The polling interval in milliseconds. Defaults to 1 minute.

var Gallop = require('gallop');

var daemon = new Gallop({
  interval: 500
});

Creating targets

A Gallop daemon subscribes to targets, which are composed of a REST API URL, an options object for the request, and a callback that fires whenever the response from that API endpoint changes. Arguments:

• url -- A string endpoint URL
• options -- An options object for the request -- see documentation for Restler's options
• callback -- A callback that takes err, result, and httpResponse to be called whenever the data changes

daemon.subscribe('//api-endpoint.provider.com/api', {
  method: 'GET',
  query: {
    api_key: 'some API key',
    some_field: 'some data for the field'
    // ...
  }
}, function(err, result, httpResponse) {
  if (err) {
    return console.error(err);
  }
  console.log(result);
});

subscribe returns a target ID, which can be passed to unsubscribe to remove the target.

// Save the target ID.
var id = daemon.subscribe( /* ... */ );

// Unsubscribe from the target.
daemon.unsubscribe(id);

Listening for changes

The Gallop daemon can start and stop; stopping in the middle of the polling cycle will complete the current cycle.

daemon.start();

// Some time later...
daemon.stop();

License

© 2013 Lehao Zhang. Released under the terms of the MIT license.