How to define custom TraceListener in app.config

Question

I have implemented a custom trace listener (derived from TextWriteTraceListener) and now I would like to set my application to use it instead of standard TextWriteTraceListener.

First I added default TextWriteTraceListener in order to make sure it works ok and it does. Here's my app.config:

<configuration>     <system.diagnostics>         <trace autoflush="true" indentsize="4">             <listeners>                 <add name="TextListener"  type="System.Diagnostics.TextWriterTraceListener" initializeData="trace.log" />             <remove name="Default" />             </listeners>         </trace>     </system.diagnostics> </configuration> 

Now my trace listener is defined in MyApp.Utils namespace and it's called FormattedTextWriterTraceListener. So I changed the type in the config above to MyApp.Utils.FormattedTextWriterTraceListener and it currently looks like that:

<configuration>     <system.diagnostics>         <trace autoflush="true" indentsize="4">             <listeners>                 <add name="MyTextListener" type="MyApp.Utils.FormattedTextWriterTraceListener" initializeData="trace.log" />             <remove name="Default" />             </listeners>         </trace>     </system.diagnostics> </configuration> 

However now when I try to log something I'm getting a ConfigurationErrorsException with the message:

Couldn't find type for class MyApp.Utils.FormattedTextWriterTraceListener.

Does anyone knows how can I set up this custom listener in config and if it's even possible?

Answer 1

Try specifying an assembly too, like so:

<configuration>     <system.diagnostics>         <trace autoflush="true" indentsize="4">             <listeners>                 <add name="TextListener"                      type="MyApp.Utils.FormattedTextWriterTraceListener, MyApp"                     initializeData="trace.log" />             <remove name="Default" />             </listeners>         </trace>     </system.diagnostics> </configuration> 

Answer 2

I've been struggling with this recently and just in case it helps anyone...

I knew my type existed so I wrote the following:

Assembly assembly = System.Reflection.Assembly.GetAssembly(typeof("yourclassname")); Type myClassType = assembly.GetType("yournamespace.yourclassname"); 

In my case, myClassType.AssemblyQualifiedName contained the string I needed in my app.config file in the type attribute.

For example:

<system.diagnostics>     <sources>       <source name="System.ServiceModel" switchValue="Information,ActivityTracing" propagateActivity="true">         <listeners>           <add name="CircularTraceListener" />         </listeners>       </source>     </sources>     <sharedListeners>       <add name="CircularTraceListener" type="Microsoft.Samples.ServiceModel.CircularTraceListener, CircularTraceListener, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null"            initializeData="C:\MyWebService\APILog\CircularTracing-service.svclog" maxFileSizeKB="1000" />     </sharedListeners>     <trace autoflush="true" />   </system.diagnostics>