ASP.NET Trace
ASP.NET introduces tracing functionality which allows one to view diagnostic information about a single request for an ASP.NET page simply by enabling it for your page or application.
Page Tracing Steps
Add trace directive at top of page
<%@ Page Trace=“True” %>
Add trace calls throughout page
Trace.Write(“Button Event Clicked”)
Trace.Warn(“Data Value: “ + checkValue)
Access page from browser
Trace Information generated :
Enabling Application-Level Tracing
To enable application level tracing add following line in Web.config :
<configuration>
<system.web>
<trace enabled=”true” localonly=”false” requestlimit=”40″>
</system.web>
</configuration>
Error Handling
ASP.NET also provides declarative application custom error handling
- Enable programmatic logging of problems
- Automatically redirect users to error page when unhandled exceptions occur
Application_Error
Application_error is global applicaion event raised if unhandled exception occurs.This provides access to Current Request object. Also , provides access to Exception object. This enables developers to log and track errors.
One can use EventLog class to write custom logs in Application_Error event. Also one can use SmtpMail class to send mails to administrators.
NT Event Log
Dim LogName As String = “MyAppLog”
Sub Application_Start(Sender as Object, E as EventArgs)
If (Not EventLog.SourceExists(LogName)) Then
EventLog.CreateEventSource(LogName, LogName)
End if
End Sub
Sub Application_Error(Sender as Object, E as EventArgs)
Dim Message As String = “Url ” & Request.Path & ” Error: ” & Me.Error.ToString()
Dim Log as New EventLog
Log.Source = LogName
Log.WriteEntry(Message, EventLogEntryType.Error)
End Sub
Sending SMTP Mail
Sub Application_Error(Sender as Object, E as EventArgs)
Dim MyMessage as New MailMessage
MyMessage.To = “contactus@alltechnicalfaqs.com”
MyMessage.From = “MyAppServer”
MyMessage.Subject = “Unhandled Error”
MyMessage.BodyFormat = MailFormat.Html
MyMessage.Body = Request.Path + Me.Error.ToString();
SmtpMail.Send(MyMessage)
End Sub