How Do I...? Common Tasks QuickStart Tutorial

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Diagnostics

Write to an event log

Read from an event log

Monitor an event log

Read from a performance counter

Count rate of change

Work with tracing

Use trace switches and listeners

Instrument a small application with tracing

How Do I...Use tracing switches and listeners?

Trace instrumentation allows developers and administrators to monitor the health of applications running in real-life settings (as opposed to running in a debugger). Sometimes using a debugger can hide bugs and obscure some performance and threading problems. Tracing is a very important monitoring and debugging tool for distributed, multitier applications. Such applications often contain problems that you can only observe when the application is under a heavy load, and in the inherent randomness of a real-life environment.

This sample illustrates the basics of using the trace and Boolean switches. A switch provides an efficient mechanism for enabling and disabling code paths at runtime using external settings. After running it, take a look at the source code. You will see how easy it is to add simple tracing to your applications. You can then go to the config file and modify the settings of the switches and then run the sample again. You will possibly get a completely different output.

Set value property of the Boolean switch to one of the following: 0 (false) or 1 (true)

Set value property of the trace switch to one of the following: 0 (off), 1 (error), 2 (warning), 3 (info), or 4 (verbose):

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
	<system.diagnostics>
		<switches>
			<add name="ABooleanSwitch" value="1" />
			<add name="ATraceSwitch" value="4" />
		</switches>
	    <trace autoflush="false" indentsize="4" />
    </system.diagnostics>
</configuration>

For more information about switches, please refer to the SDK documentation.

You have to compile your instrumented applications with trace or debug compiler directives enabled. Otherwise, all calls to Trace or Debug (respectively) are ignored during compilation.

Before running the application, open a command line window and run the Debug Monitor utility (DBMon.exe). You will be able to see all debug and trace messages coming from any application running on your system.

Creating new event log sources requires administrative rights. Since this sample creates "SwitchesDemo" source, you need to run it under an administrative account.

Note: DBMon.exe is available from the Windows Platform SDK on the Microsoft Developer Network website.

Example

C# Switches.exe

[This sample can be found at M:\web\users\sites\AspnetQuickStart\v2.0\QuickStart\howto\samples\Services\Tracing\Switches\
To build this sample, open the SDK command prompt and navigate to the above path. Build the sample using the build tool msbuild passing the solution file as the first parameter: msbuild mySample.sln. The compiled executable will be found in the sub directory \bin directory.]