Extending the Logging Application Block

The Logging Application Block is designed to suit a variety of applications and to supply the most commonly used logging functions. Additionally, with extension points, you can adapt the application block to suit the needs of any particular application. You can extend the capabilities of the application block by adding custom trace listeners, filters, and formatters.

To extend the Logging Application Block

1. Create a new custom class and add it to your project.
2. Make sure that the class implements the required interfaces, constructors, and methods.
3. Create the custom object in the Enterprise Library Configuration Console.
4. Specify your custom class as the type name.
5. Specify any custom configuration properties by modifying the attributes of the object.

To create a custom formatter

1. Create a new class, and then add it to your project.

2. (Optional) To use elements without fully qualifying the element reference, you can add the following using statement (C#) or Imports statement (Visual Basic) to the top of your source code file.

   using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;
   using Microsoft.Practices.EnterpriseLibrary.Logging;
   using Microsoft.Practices.EnterpriseLibrary.Logging.Configuration;
   

   'Usage
   Imports Microsoft.Practices.EnterpriseLibrary.Common.Configuration
   Imports Microsoft.Practices.EnterpriseLibrary.Logging
   Imports Microsoft.Practices.EnterpriseLibrary.Logging.Configuration
   

   Note

   For Visual Basic projects, you can also use the References page of the Project Designer to manage references and imported namespaces. To access the References page, select a project node in Solution Explorer, then on the Project menu, click Properties. When the Project Designer appears, click the References tab.

3. Specify that the class implements ILogFormatter.

4. Add the class attribute ConfigurationElementType. Specify the type CustomFormatterData as the attribute parameter.

   [ConfigurationElementType(typeof(CustomFormatterData))]
   public class MyFormatter : ILogFormatter
   

   'Usage
   <ConfigurationElementType(GetType(CustomFormatterData))> _
   Public Class MyFormatter: Implements ILogFormatter
   

5. Add a constructor that has parameter of type NameValueCollection.

   public MyFormatter (NameValueCollection attributes)
   {
   }
   

   'Usage
   Public Sub New(ByVal attributes As NameValueCollection)
   
   End Sub
   

6. Add the Format method to your class, and then implement the required behavior.

   public string Format(LogEntry log)
   {
   } 
   

   'Usage
   Public Function Format(ByVal log As LogEntry) As String End Function
   

For more details about how to extend the Logging Application Block, with an example that shows how to create a custom event sink, see Creating a Custom Trace Listener.