How Orchard CMS does the logging?

Question

I'm working with Orchard CMS and it is better CMS for me. I want to understand how it does the logging and whether I can add my own logging or not. I saw that Orchard uses NullLogger class and it does no work. I've opened the App_Data.Logs folder and have seen that there are the log files. But how? I searched in code where is the trick that replaces NullLogger with log4net (I guess this is log4net, because the log format and the formatting for log4net.config are very similar) but I haven't found this. Can somebody answer me:

1. How Orchard does the logging?
2. Whether I can add my own logger and if yes what best practices exist to do this?

Thanks, Andrey.

Answer 1

An Autofac module (Orchard.Logging.LoggerModule to be precise) handles that. Basically - it scans each dependency and fills all properties of type ILogger with a reference to appropriate logger instance. Each dependency gets its own logger with name equal to full type name (including namespace) of a containing class.

The NullLogger is just a placeholder so accessing the property would not throw NullReferenceExceptions before the property is being set by Autofac.

Extending the default logging is a rather complicated task as it would involve doing three things:

• create a custom implementation of ILoggerFactory (just like the default Orchard.Logging.CastleLoggerFactory) and
• create an Autofac module that registers that implementation in the container (like the mentioned LoggerModule does)
• suppress the current default logging module by decorating your new one with [OrchardSuppressDependency("Orchard.Logging.LoggingModule")]

UPDATE

Just realized I haven't addressed the most important part of the question here:) Yes, Orchard uses log4net so you may alter the default settings via Config/log4net.config file.