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Populating a Log Message with Additional Context Information

  • Artikkeli

The LogEntry class defines properties to hold information common to typical logging scenarios. Developers often need to add context information to log entries. The same type of context information can be required for multiple log entries in the same application or in multiple applications. Because context information can be expensive to gather, certain types of information are not automatically collected. The ExtraInformation providers gather context information that is useful but not always necessary because it is expensive to collect. Examples are stack trace information and COM+ information.

Typical Goals

In this scenario, you want to add a collection of related properties to a log entry. The values of the properties are determined by the specific context of the application at the time the log entry is created. For example, you want to add security-related properties such as the Windows identity and authentication status of the current user.

Solution

Use the application block classes that implement IExtraInformationProvider to populate a collection of properties. Use the ExtendedProperties property of the LogEntry class to pass the collection of properties to the Write method of the LogWriter class.

The Logging Application Block includes the following classes that derive from IExtraInformationProvider:

  • ComPlusInformationProvider. This class populates the collection with the following commonly needed COM+ diagnostic information:
    • Activity ID
    • Application ID
    • Transaction ID
    • Direct caller account name
    • Original caller account name
  • DebugInformationProvider. This class populates the collection with a property containing the current stack trace information.
  • ManagedSecurityContextInformationProvider. This class populates the collection with the following commonly needed security-related information from the managed runtime:
    • Authentication type
    • Current identity name
    • Authentication status
  • UnmanagedSecurityContextInformationProvider. This class populates the collection with the following commonly needed unmanaged security-related information:
    • Current user
    • Process account name

Populating a Dictionary with Context Information

The following code shows how to use the ManagedSecurityContextInformationProvider class to populate a dictionary with security-related information.

Dictionary<string, object> dictionary = new Dictionary<string, object>();
ManagedSecurityContextInformationProvider informationHelper 
  = new ManagedSecurityContextInformationProvider();    
informationHelper.PopulateDictionary(dictionary);

'Usage
Dim dictionary As New Dictionary(Of String, Object)()
Dim informationHelper As New ManagedSecurityContextInformationProvider()
informationHelper.PopulateDictionary(dictionary)

You can also add custom properties to the dictionary. The following code shows how to add the current screen resolution to the collection of properties declared in the previous example.

int width = Screen.PrimaryScreen.Bounds.Width;
int height = Screen.PrimaryScreen.Bounds.Height;
string resolution = String.Format("{0}x{1}", width, height);
dictionary.Add("Screen resolution", resolution);

'Usage
Dim width As Integer = Screen.PrimaryScreen.Bounds.Width
Dim height As Integer = Screen.PrimaryScreen.Bounds.Height
Dim resolution As String = String.Format("{0}x{1}", width, height)
dictionary.Add("Screen resolution", resolution)

The following code shows how to add the collection of properties to a LogEntry object stored in the variable named myLogEntry.

myLogEntry.ExtendedProperties = dictionary;

'Usage
myLogEntry.ExtendedProperties = dictionary