13.6. Writing Trace Data to the Event Log with Controllable Levels
You want your application to output trace information to the event log and, at the same time, control what level of information is output.
Modify web.config to:
In the classes you want to output trace information, create a
TraceSwitch object using the name of the
TraceSwitch you added to the web.config file, and use the
WriteLineIf methods of the
Trace class to output the required messages, as we demonstrate in our sample application shown in Examples 13-19, 13-20 through 13-21.
The technique we advocate for writing trace information to the event log involves adding the
EventLogTraceListener to the listener collection in web.config to write the trace information to the event log. We find it useful to control the level of messages output to the event log, such as outputting only error messages or outputting error and warning messages. Controlling the level of messages that are output involves the use of switches (more about this in a minute).
As discussed in Recipe 13.5, you can add additional listeners to the
TraceListeners collection via the web.config file. When a
Trace.WriteLine is executed, all listeners in the
TraceListeners collection receive and process their output.
The support that ...