This document discusses ASP.NET Health Monitoring. It provides examples of bad exception handling practices and explains why trying again is a bad idea. It then discusses how Health Monitoring can be used to be notified of errors and application events. Notifications can be sent to the Windows Event Log, SQL Server, email, or other providers. Profiles like Default and Critical can be used to define notification rules. Health Monitoring provides a convenient way to monitor application errors and keep track of issues.

1. ASP.NET Health Monitoring
Milan Negovan

2. MILAN
NEGOVAN
ROASTS ASP.NET WITH WEB STANDARDS
ASP.NET CONSULTING SERVICES
http://aspnetresources.com
milan@aspnetresources.com

5. 9 times of out 10
there’s
nothing
you can
do

6. But…
You must
know
about it

7. Exception handling
“greatest hits”

8. Why I think “trying
again” is a bad idea.

9. catch (Exception ex)
{
string txt = ex.Message;
}
Exhibit A: a meaningless assignment

10. catch (Exception XXX)
{
string txt = XXX.Message;
}
Exhibit B: an adult version of the same

11. catch (Exception ex)
{
return false;
}
Exhibit C: a “magic” return value

12. catch (Exception ex)
{
res = -1;
}
Exhibit D: C++ blues

13. catch (Exception ex)
{
}
Exhibit E: horrible exception swallowing

14. catch { }
Exhibit F: same

15. catch (Exception Ex)
{
int i;
i=0;
}
Exhibit G: spinning one’s wheels

16. catch (Exception ex)
{
throw ex;
}
Exhibit H: you gain what again?

17. public static bool SendEmail (
string To,
string From,
string Subject,
string Body,
bool HtmlFormatted,
out Exception error)
{
//...
}
Exhibit I: catch me if you can

18. Why so averse to
exceptions?

19. Set up a custom error page
<customErrors
defaultRedirect="~/errors/GenericError.aspx"
mode="RemoteOnly" />

20. Save yourself embarrassment

21. So what is Health
Monitoring about?

23. The “what”
What do you want to be notified about?

25. Preconfigured event mappings:
•All events. Anything and everything that happens on
your site.
•Application Lifetime Events. Application compilation,
start-up and shutdown.
•All Errors. Any and all errors on the site.
•Infrastructure Errors. Compilation, configuration, parse,
etc, errors.
•Request Processing Errors. View state and validation
errors, as well as all unhandled exceptions.

26. Demo
Custom events

27. The “how”
How do you want them delivered?

28. ASP.NET 2.0 ships with the
following providers:
• Windows Event Log
• SQL Server
• E-mail
• WMI
• Diagnostics Tracing

30. Custom providers
Look it up ;)

32. Profiles: default and critical
<profiles>
<add
name="Default"
minInstances="1"
maxLimit="Infinite"
minInterval="00:01:00" />
<add
name="Critical"
minInstances="1"
maxLimit="Infinite"
minInterval="00:00:00" />
</profiles>

33. Buffering
Look it up ;)

34. By default all errors are logged in the
system event log
<rules>
<add
name="All Errors Default"
eventName="All Errors"
provider="EventLogProvider"
profile="Default"
minInstances="1"
maxLimit="Infinite"
minInterval="00:01:00" />
…
</rules>

35. Demo
A simple exception thrown and
written to the system event log.

36. Tip
Remember to deploy with debug
symbols.

37. Health Monitoring as a
convenient way to keep
track of whose fault it is.

38. Questions

39. Goodies
 Keeping Pulse on Your Site With ASP.NET 2.0
Health Monitoring
 Why So Averse To Exceptions?
 How To: Instrument ASP.NET 2.0 Applications for
Security
 How to: Send E-mail for Health Monitoring
Notifications
 Raising Custom ASP.NET Health Monitoring
Events Example