logness v0.0.2

Logness

A wrapper for the Mac OS X syslog log message viewer.

If you just initialize a Logness without a filtering function the Logness will emit on every log item that goes into the system syslog.

A Logness that would grep all incoming log messages and display their sender and error level could be written as:

var Logness = require('logness');
var logs = new Logness();

logs.on('message', function(data) {
    console.log([data.sender, data.level].join(' '));
});

Filtering

If you pass in a function when you initialize a Logness, you can filter the messages it will react to.

var Logness = require('logness');
var mail = new Logness(function() {
    /* grep everything send to mail with an error level above 3 */
    return this.sender === 'Mail' && this.level > 3;
});

mail.on('message', function(data) {
    console.log(data.time, data.message);
});

The function passed to Logness should return a Boolean value; true if the Logness instance should react on the message, and false if it should be ignore it. If no function is passed it will get passed a 'catch all'-function that return true for every message, in other words; the Logness instance will get every message.

Inside the filtering function this refers to the message data.

Message format

The message should have the following data attached to it:

• sender {string} The name of the program that send the message

• pid {number} process id of the sender

• message {string} what happened

• time {date} the time it happened

• level {number} error level

• host {string} the name of the machine where the log occurred

Todo

• Make this work for BSD, Linux and other operating systems. Perhaps make a plugin system, that enables Logness to understand other log formats.

• Fix the way the obejcts get notified about messages. I don't know if I like the way it is currently implemented.