Tracing - (WCF)

Tracing is an important aspect of developing and debugging Windows Communication Foundation (WCF) services. Tracing allows you to log messages about the internal workings of your service, such as when requests are received, when responses are sent, and when errors occur. This can be very helpful when trying to diagnose problems with your service.

Syntax

To enable tracing in a WCF service, you can configure tracing settings in the configuration file. Here is an example of how to enable tracing in a WCF service:

<configuration>
  <system.diagnostics>
    <sources>
      <source name="System.ServiceModel" 
              switchValue="Information, ActivityTracing"
              propagateActivity="true">
        <listeners>
          <add name="traceListener" />
        </listeners>
      </source>
    </sources>
    <sharedListeners>
      <add name="traceListener"
           type="System.Diagnostics.XmlWriterTraceListener"
           initializeData="c:\logs\trace.log" />
    </sharedListeners>
  </system.diagnostics>
  ...
</configuration>

Example

Here is an example of how to use tracing in a WCF service:

using System;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Description;

namespace MyNamespace
{
  [ServiceContract]
  public interface IMyService
  {
    [OperationContract]
    string MyMethod(string input);
  }

  public class MyService : IMyService
  {
    public string MyMethod(string input)
    {
      // Log a message
      System.Diagnostics.Trace.TraceInformation("MyMethod called with input: " + input);

      // Do some work
      var output = input.ToUpper();

      // Log a message
      System.Diagnostics.Trace.TraceInformation("MyMethod returned output: " + output);

      // Return the output
      return output;
    }
  }

  class Program
  {
    static void Main(string[] args)
    {
      // Create a new instance of the service
      var service = new MyService();

      // Create a new ServiceHost for the service
      var host = new ServiceHost(service, new Uri[] { new Uri("http://localhost:8000") });

      // Enable tracing
      var config = host.Description.Behaviors.Find<ServiceDebugBehavior>();
      if (config == null)
      {
        config = new ServiceDebugBehavior() { IncludeExceptionDetailInFaults = true };
        host.Description.Behaviors.Add(config);
      }
      else
      {
        config.IncludeExceptionDetailInFaults = true;
      }

      // Open the ServiceHost
      host.Open();

      // Wait for the user to press a key
      Console.WriteLine("Press any key to stop the service...");
      Console.ReadKey();

      // Close the ServiceHost
      host.Close();
    }
  }
}

Output

When you run the WCF service that has tracing enabled, you should see log messages in the trace file that look something like this:

<TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Information">
  <TraceIdentifier>http://msdn.microsoft.com/en-US/library/System.ServiceModel.Diagnostics.TraceOperationVerbose.aspx</TraceIdentifier>
  <Description>Activity boundary</Description>
  <AppDomain>MyService.exe</AppDomain>
  <ExtendedData xmlns="http://schemas.microsoft.com/2006/08/ServiceModel/DictionaryTraceRecord">
    <ActivityName>MyMethod</ActivityName>
    <ActivityType>http://schemas.microsoft.com/2004/09/ServiceModel/WebServiceTraceRecord/Verbose</ActivityType>
    <Arguments xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/Arrays">
      <a:anyType xmlns="">[input value]</a:anyType>
    </Arguments>
  </ExtendedData>
</TraceRecord>

Explanation

In the example code, we define a simple WCF service that has one method (MyMethod) that logs messages using the System.Diagnostics.Trace class. The Main method of the console application creates an instance of the service and opens a ServiceHost to host the service. We then configure tracing in the WCF service by adding a ServiceDebugBehavior to the service host description, which enables tracing of exception details in faults and routes the tracing messages to a specific file location. We then open the ServiceHost and wait for the user to stop the service.

Use

Tracing is an important tool for diagnosing problems with your WCF service. By enabling tracing and logging messages about the internal workings of your service, you can gain insight into what is happening when errors occur.

Important Points

• Tracing can be used to log messages about the internal workings of your WCF service, such as when requests are received, when responses are sent, and when errors occur.
• Tracing can be configured in the configuration file for your WCF service.
• The System.Diagnostics.Trace class can be used to log messages in WCF service methods.

Summary

In this page, we discussed how to use tracing in a WCF service. We covered the syntax, example, output, explanation, use, important points, and summary of using tracing with a WCF service. Tracing is an important tool for diagnosing problems with your WCF service, and can be configured in the configuration file for your service. By logging messages about the internal workings of your service, you can gain insight into what is happening when problems occur.