A good rule of thumb about exceptions is that if you can't do something
with the exception (i.e. handle it gracefully or recover from it) then
you shouldn't be catching it. I usually catch exceptions at higher
levels (my user interface or business layer) and let lower levels such
as my data level simple bubble the exceptions up.
What items are are you pushing onto the NDC?
When you talk about the NDC and catch blocks, are you doing this:
using(NDC.Push("test1"))
{
try
{
generateApplicationException("Oh no!");
}
catch (Exception ex)
{
log.Error("Unexpected error. Cause: " + ex.Message, ex);
}
}
Are you loosing the NDC inside of the catch block? Are you aware of the
other context objects:
http://logging.apache.org/log4net/release/manual/contexts.html
If you want to keep the contents of the NDC seperate from the logging
message itself, have you thought about creating a simple XML layout
that does that (the log4j schema may or may not already do this):
<log>
<message>Unexpected error. Cause: Oh no!</message>
<exception>
... ApplicationException ...
</exception>
<ndc>
<item level="0">test1</item>
<ndc>
</log>
Does that help any?
--- Duncan Woods <[EMAIL PROTECTED]> wrote:
> Hi all,
>
> I don't think I have grasped something basic about using error
> handling
> as I am having trouble integrating exceptions with logging. The goal
> of
> my logging is at high levels to be comprehensible to a non software
> engineer and provide sufficient information to fix any problem that
> has
> occurred. Exceptions are the default error handling of .Net and
> almost
> every object can throw them in some situation. Catch handlers around
> every call is not realistic but the level of detail I add to the NDC
> is
> sufficient.
>
> The problem is that if I log an exception message at the catch
> handler,
> I have lost the context of the NDC and the resultant log message is
> unhelpful. What are the other options? What design guidelines do you
> set
> down?
>
> i) Log the exception's call stack
>
> This does not give presentable messages
>
> ii) Log and throw at the same time
>
> This can cause the same message to be logged repeatedly through
> the
> hierarchy as the error ripples up to the top level. Ugly and harms
> admin's ability to use log4net to trigger actions based on trace
> message
> contents.
>
> c) Append the NDC to an exception message
>
> Suffers from both the previous problems - its not nice that the
> NDC
> becomes part of them message and rethrowing an exception will cause
> multiple copies of the NDC.
>
>
> Thanks in advance for your ideas,
>
> Duncan
