Scout

Class: Scout

This is a class you inherit from when writing custom device drivers. Scouts are used to search for devices with external node modules, or protocols. It's used by require('zetta-scout'). You must inherit from the Scout class when building custom Zetta modules.

var util = require('util');
var Scout = require('zetta-scout');

function DeviceScout(){
  Scout.call(this);
}
util.inherits(DeviceScout, Scout);

Method: Scout#init(next)

• next Function

This method should be implemented by you. This allows you to initialize any resources like bluetooth access, serial ports, or vendor modules needed to look for devices. The argument next is provided, and must be called after scouting has started. This notifies Zetta that the scouting process is done, and can move on to another scout if needed.

DeviceScout.prototype.init = function(next) {
  var connection = Serial.connect(function(){
  });

  connection.on('start', function(){
    next();
  });
};

Method: Scout#discover(constructor, [arguments])

• constructor Subclass of Device
• arguments List of Objects

This method is called by you when you've found your device. The constructor argument should be a subclass of Device, and the second argument is a list of objects to be used by the constructor.

DeviceScout.prototype.init = function(next) {
  this.discover(DeviceDriver, foo, bar, 'baz');
};

Method: Scout#provision(deviceObject, constructor)

• deviceObject Object
• constructor Subclass of Device

Zetta will persist device data to an internal registry. Using an object retrieved from this registry you can initialize a device that Zetta already knows about. The first argument deviceObject is just data on the object from Zetta. The constructor argument is what will be created by Zetta.

DeviceScout.prototype.init = function(next) {
  var deviceObject = {
    name:'testObject',
    id: '123',
    foo: 'bar'
  };
  this.provision(deviceObject, DeviceDriver);
};

Property: Scout#server

This gives access to the zetta runtime. Here you can issue queries and lookup devices that Zetta already knows about.

DeviceScout.prototype.init = function(next) {
  var self = this;

  // query registry for any device that has type led and an id that we know of.
  var query = this.server.where({ type: 'lcd', id: 'some-id' });
  this.server.find(query, function(err, results) {
    if (results.length > 0) {
      // found in registry, tell zetta it came online
      self.provision(results[0], DeviceDriver, foo, bar, 'baz');
    } else {
      // does not exist in registry, discover a new one.
      self.discover(DeviceDriver, foo, bar, 'baz');
    }
  });
};