Log implementation and configuration

[sebez]

On CI-T, I added log4javascript for client logging :

It uses log4j-like configuration and API with named loggers, appenders, level, layout, etc.
Available appenders include : console appender, DOM appender, popup appender, Server API appender. Adding new appender (for instance a localStorage appender) seems uncomplicated.

Currently, Focus is logging using a hard-coded reference to a generic unnamed hand-made unconfigurable logger, or uses directly the console object.

It would be nice :

• to use log4javascript loggers instead,
• to use an injection mecanism that would allow to configure the named loggers (appender / level) outside Focus in the application.

Here is how it's done on CI-T :

Setup

Logger directory

In the application root, I added a loggers directory :

• app
  • loggers
    • index.js
    • Spa.Application.js
    • Spa.View.js

Declaration

Each logger is declared in its own module as a singleton :

var log = log4javascript.getLogger("Spa.Application");

module.exports = log;

Configuration

The main index.js script sets up the configuration of the loggers.

/* Chargement des singletons de logger */
var logSpaApplication = require('./Spa.Application');
var logSpaView = require('./Spa.View');

/* Définition des appenders */
var consoleAppender = new log4javascript.BrowserConsoleAppender();
consoleAppender.setLayout(new log4javascript.PatternLayout("%d{HH:mm:ss,SSS} %c %p %m"));

/* Configuration des loggers */
logSpaApplication.addAppender(consoleAppender);
logSpaView.addAppender(consoleAppender);

Initialization

In the application intialize script, the first thing to do is to call the loggers main script :

var initialize = {
    init: function init(params) {
        return $(function () {

            /* Init loggers. */
            require('./loggers/index');            

            /* ... */

            /* Initialize application. */
            application.initialize();
        });
    }
};

module.exports = initialize;

Usage

var log = require('./loggers/Spa.Application');
log.info("Démarrage SPA...");

Result in Chrome console :