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Thursday, June 7, 2012

4 simple steps to enable tracing in WCF

Tracing mechanism in Windows Communication Foundation is based on the classes that resides in System.Diagnostic namespace.Important classes are Trace, TraceSource and TraceListener. For better understanding we will follow step by step approach in this WCF Tutorial.

Following are the steps to enable tracing in WCF:

1. Configuring WCF to emit tracing information/Define Trace Source, we have the following options:
  • System.ServiceModel 
  • System.ServiceModel.MessageLogging 
  • System.ServiceModel.IdentityModel
  • System.ServiceModel.Activation 
  • System.Runtime.Serialization 
  • System.IO.Log
  • Cardspace
      In configuration file, we will define a source to enable this configuration as follows:
      <source name="System.ServiceModel.MessageLogging">

2. Setting Tracing Level, we have the following available options, we need to set this tracing level to available options other than default "Off":
  • Off
  • Critical
  • Error
  • Warning
  • Information
  • Verbose
  • ActivityTracing
  • All
      In configuration file, we can choose above values for switchValue attribute as follows:
      <source name="System.ServiceModel.MessageLogging"

3. Configuring a trace listener
    For configuring a trace listener, we will add following to config file.
                 <add name="messages"
                 initializeData="d:\logs\messages.svclog" />

4. Enabling message logging
logEntireMessage: By default, only the message header is logged but if we set it to true, entire message including message header as well as body will be logged.
logMalformedMessages: this option log messages those are rejected by WCF stack at any stage are known as malformed messages.
logMessagesAtServiceLevel: messages those are about to enter or leave user code.
logMessagesAtTransportLevel: messages those are about to encode or decode.
maxMessagesToLog: maximum quota for messages. Default value is 10000.
maxSizeOfMessageToLog: message size in bytes.

Putting all this together, configuration file will appear like this.
      <source name="System.ServiceModel.MessageLogging">
          <add name="messagelistener"
               type="System.Diagnostics.XmlWriterTraceListener" initializeData="d:\logs\myMessages.svclog"></add>
        <messageLogging logEntireMessage="true"
Note: In this case, information will be buffered and not published to file automatically, So, we can set the autoflush property of the trace under sources as follows:
<trace autoflush ="true" />

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By Imran Abdul Ghani
Software Developer (Senior)
United Arab Emirates
Imran Abdul Ghani is working as Software Developer(Senior) with extensive knowledge in Web development technologies especially C#, ASP.NET, MVC, WCF, Web API, ADO.NET Entity Framework, jQuery etc. He has several years of experience in designing/developing enterprise level applications. He is Microsoft Certified Solution Developer for .NET (MCSD.NET) since 2005. You can reach his blogging at www.webdevelopmenthelp.net & www.topwcftutorials.net.


  1. Thanks, this certainly helps alot. :-)

  2. where to put this? client app or wcf app?

    1. Dear, put this on wcf service configuration file.

  3. It seems to me that one also needs to make sure the identity that the AppPool executes under must have write permisisons to the log file location.