Module: core/loggers

• always logs each new value when those are emitted/communicated by the address driver.
• on_update logs new values only if the new value is not equal to the previous value known by the system. Typically in KNX, it is possible that a device periodically writes a group address with the same value.
• every x milliseconds. The system logs the last known value cyclically. It may be used for example to log values every 15 minutes.

{	
	'1':{
		id: 1,
		name: 'mysql usb',
		description: 'logs mysql',
		driver: 'mysql.js', //link to the Javascript driver file used to log values.
		active: 1,
		state: 'connected',  //The state can be "disconnected", "connecting", or "connected"
		json: {  // logger driver parameters
			storage: 'usb' 
		},
		private_json: {}  // can be used by applications to store custom information
	}, ...
} 

var query = {
	// query datetime interval : 
	
	'start' :  new Date(), // Javascript date object, or timestamp in milliseconds (epoch time)
	'end'	: ...		,  // Javascript date object, or timestamp in milliseconds (epoch time)
	
	// gateways
	
	'address' 	:  ['14/7/5', '14/7/3'], //one address identifier (address id, name, or alias), or an array of address identifiers.
	
	
	// optional parameters. it defines if the values should be aggregateed over a time period.
	// The computed aggregates are the average, min, max.
	
	'aggregate' :  '15m' 	// defines the time period. It is an integer suffixed with its time unit. 
							// s => seconds 
							// m => minutes 
							// h => hours 
							// d => day 
							// w => week 
							// o => month
							// y => year
	
	// optional pack parameters. It specifies if rows are packed or not before calling the streamCallback.
	
	'pack' : 100  //here the streamCallback (e.g. function(err,rows){...}) would return rows by packs of maximum 100 rows.	
	
}

//example of executing a query : 

loggers.query({  // returns 15 minutes aggregates(min, max, and average) for KNX address 4/7/25 
	address : '4/7/25',
	start   : new Date(), // now, 
	end	    : new Date(new Date().setDate(new Date().getDate()-1)), //yesterday
	aggregate : '15m'
}, function(err, row){
	// is called multiple times. returns each rows.
	// when the streaming has end, err 'end' is sent.
	
	if(err == 'end'){
		
	}else{
		console.log(row) // where row contains the address, timestamp, and the value or aggregated values.
	}	
})

//for gateways : 

loggers.on('loggerInserted',function(newLogger){ ... })
loggers.on('loggerUpdated',function(updatedLogger, oldLogger){ ... })
loggers.on('loggerDeleted',function(deletedLogger){ ... })
loggers.on('loggerState',function(loggerId, state){ 
	// logger numerical id
	// where state equal to 'connecting', 'connected', or 'disconnected' 
})