Tracing in WCF: Understanding basic steps

Theory behind WCF Tracing is not an exception of classical definition of Tracing. Through Tracing an application provides information about itself. Information may vary from internal state of object to passed input parameter to method. This information should be logged, persisted or saved somewhere.

WCF Tracing can be used for the instrumentation of the WCF Service.

There are essentially four steps involved in WCF Tracing

Emitting Trace information from Service

To emit trace information WCF provides different sources. However you have choice to create trace source using TraceSource class as well. You can choose any of WCF Assembly level trace source to emit the tracing information.

WCF Assembly level Trace Sources are as below,

System.ServiceModel
System.ServiceModel.MessageLogging
System.ServiceModel.IdentityModel
System.ServiceModel.Activation
System.Runtime.Serilization
System.IO.Log

Setting the Trace level

You can define the level of messages you want to trace. If you are tracing all level of messages then size of message generated for tracing would be very bulky and it may affect application negatively.

WCF supports below tracing levels

Trace level information is set by using the switchValue attribute for trace source.

Configuring the listener

You need to configure a listener to persist the messages at any desired location. There must be at least one listener configured for WCF tracing.

Listener can be configured either

Through code
Or in configuration file.

You can configure listener directly in source element of the configuration.

Note: In further post, I will discuss in detail on configuring the listener.

Enabling Message logging

Last step you need to perform is to enable message logging in configuration. WCF logs message at two levels.

Different attributes of Message loggings are as below,

Enough of theory Smile Now let us go ahead and capture basic trace in WCF service.

Create a basic WCF Service
Consume service in a client. I am assuming that you are consuming service in a console client.
Open App.config of console client

Emit Trace Information

Add a source in System.Diagostics

Set the Trace Level

We are setting here trace level to Information and Activity tracing

Configure the Listener

We are using listener System.Diagnostics.XmlWriterTraceListener. Trace information would be find at Traces.svclog file under bin/debug folder .

Trace information gets buffered, so to make it visible you need to flush it using below configuration

After performing above three steps your System.Diagnostics should look like below,

Enable Message Logging

Last step you need to perform is enabling Message logging. Add below diagnostic in System.ServiceModel.

Eventually client side App.Config should look more or less like below, Smile


<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.serviceModel>
      <diagnostics>
        <messageLogging logEntireMessage="true"
                        logMalformedMessages="false"
                        logMessagesAtServiceLevel="false"
                        logMessagesAtTransportLevel="true"
                        maxMessagesToLog="3000"
                        maxSizeOfMessageToLog="2000"/>
      </diagnostics>
        <bindings>
            <wsHttpBinding>
                <binding name="WSHttpBinding_IService1" closeTimeout="00:01:00"
                    openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
                    bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard"
                    maxBufferPoolSize="524288" maxReceivedMessageSize="65536"
                    messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true"
                    allowCookies="false">
                    <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384"
                        maxBytesPerRead="4096" maxNameTableCharCount="16384" />
                    <reliableSession ordered="true" inactivityTimeout="00:10:00"
                        enabled="false" />
                    <security mode="Message">
                        <transport clientCredentialType="Windows" proxyCredentialType="None"
                            realm="" />
                        <message clientCredentialType="Windows" negotiateServiceCredential="true"
                            algorithmSuite="Default" establishSecurityContext="true" />
                    </security>
                </binding>
            </wsHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://localhost:2934/Service1.svc" binding="wsHttpBinding"
                bindingConfiguration="WSHttpBinding_IService1" contract="ServiceReference1.IService1"
                name="WSHttpBinding_IService1">
                <identity>
                    <dns value="localhost" />
                </identity>
            </endpoint>
        </client>
    </system.serviceModel>
  <system.diagnostics>
    <sources>
      <source name="System.ServiceModel.MessageLogging"
              switchValue="Information, ActivityTracing">
        <listeners>
          <add name="log"
               type="System.Diagnostics.XmlWriterTraceListener"
               initializeData="Traces.svclog"/>
        </listeners>
      </source>
    </sources>
    <trace autoflush ="true"/>
  </system.diagnostics>
</configuration>

After configuring as said above when you run client application you will get a file in

Bin\debug\Traces.svclog

Open above file to view the trace Smile I hope this post was useful. In further post I will take you to dipper in tracing. Thanks for reading Smile

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