Logging Facility

The logging facility provides a seamless way to add logging capabilities to your application. There are two levels of integration.

• Allow your classes to receive an ILogger instance for logging support
• Allow you to ask for an ILoggerFactory instance to provide logging support to classes that are not managed by Windsor.

:information_source: Logger abstraction: Castle Project does not contain its own logging framework. There are already excellent frameworks out there. Instead ILogger and ILoggerFactory are abstractions Windsor uses to decouple itself from the framework you decide to use.

Loggers

Castle Core provides many logger abstraction implementations, however you can also create your own.

Registering the facility

In code

The recommended way of configuring the facility is using code. When specifying custom ILoggerFactory or IExtendedLoggerFactory you use the following generic overload:

container.AddFacility<LoggingFacility>(f => f.LogUsing<CustomLoggerFactory>());

For example, using the log4net logger factory with configuration stored in a log4net.xml file, the code would look like this:

container.AddFacility<LoggingFacility>(f => f.LogUsing<Log4netFactory>().WithConfig("log4net.xml"));

Built-in logging factories

There are a few helper methods for built-in logging factories:

// Null Logger
container.AddFacility<LoggingFacility>(f => f.LogUsingNullLogger());

// Console Logger
container.AddFacility<LoggingFacility>(f => f.LogUsingConsoleLogger());

// Diagnostics Logger
container.AddFacility<LoggingFacility>(f => f.LogUsingDiagnosticsLogger());

// Trace Logger
container.AddFacility<LoggingFacility>(f => f.LogUsingTraceLogger());

Via XML Configuration

It is also possible to configure the facility via XML. For example the same configuration for log4net as above:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
   <facility
      type="Castle.Facilities.Logging.LoggingFacility, Castle.Facilities.Logging"
      customLoggerFactory="Castle.Services.Logging.Log4netIntegration.Log4netFactory, Castle.Services.Logging.Log4netIntegration"
      configFile="log4net.xml" />
</configuration>

The full list of configuraation attributes is shown in the following example:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
   <facility
      type="Castle.Facilities.Logging.LoggingFacility, Castle.Facilities.Logging"
      customLoggerFactory="<type of factory>"
      configFile="<path to configuration file (optional attribute)>"
      loggerLevel="<the loggerLevel (optional attribute)>"
      configuredExternally="<boolean value (optional attribute)>" "/>
</configuration>

Best practices

We recommend that you make logging optional on your components/services. This way you maximize the reusability. For example:

using Castle.Core.Logging;

public class CustomerService
{
   public CustomerService()
   {
   }

   public ILogger Logger { get; set; } = NullLogger.Instance;

   // ...
}

With the approach above, the logger field will never be null. Also, if the logging facility was registered on the container, it will be able to supply a logger instance using the Logger property.

Required Assemblies

• Castle.Facilities.Logging.dll (bundled with Windsor)
• Castle.Core.dll (contains the ILogger and ILoggerFactory interfaces; included as a dependency in the Windsor NuGet package)