<add> Element for <listeners>

Article
10/23/2006

Adds a listener to the Listeners collection.

<add name="name" 
     type="trace listener class name, Version, Culture, PublicKeyToken"
     initializeData="data"/>

Required Attributes

Attribute	Description
type	Specifies the type of the listener. You must use a string that meets the requirements specified in Specifying Fully Qualified Type Names.

Optional Attributes

Attribute	Description
initializeData	The string passed to the constructor for the specified class.
name	Specifies the name of the listener.

Remarks

The Debug and Trace classes share the same Listeners collection. If you add a listener object to the collection in one of these classes, the other class uses the same listener. The listener classes shipped with the .NET Framework SDK derive from the TraceListener class.

The value for the initializeData attribute depends on the type of listener you create. Not all trace listeners require you to specify initializeData. The following table shows the trace listeners that ship with the .NET Framework SDK and describes the value of their initializeData attributes.

Trace listener class	initializeData attribute value
System.Diagnostics.EventLogTraceListener	The name of the event log trace listener.
System.Diagnostics.TextWriterTraceListener	The name of the file that the TextWriterTraceListener writes to.

Example

The following example shows how to use <add> elements to add the listeners MyListener and MyEventListener to the Listeners collection. MyListener creates a file called MyListener.log and writes the output to the file. MyEventListener creates an entry in the event log.

<configuration>
   <system.diagnostics>
      <trace autoflush="true" indentsize="0">
         <listeners>
            <add name="MyListener"
                 type="System.Diagnostics.TextWriterTraceListener, Version, Culture, PublicKeyToken" 
                 initializeData="MyListener.log"/>
            <add name="MyEventListener"
                 type="System.Diagnostics.EventLogTraceListener, Version, Culture, PublicKeyToken" 
                 initializeData="MyConfigEventLog"/>
         </listeners>
      </trace>
   </system.diagnostics>
</configuration>

Configuration File

This element can be used in the machine configuration file (Machine.config) and the application configuration file.