Hi Erich.
Nice to hear from you. While I'm fairly new to the NHibernate logging
world, it seems that it would be very useful to attach a lightweight
log monitor in a logger-independent manner. For example, regardless
of the full logging framework being used, you would be able to
register a handler that fires an event whenever it sees appropriate
log messages. This would allow code that uses information from the
logs to attach itself easily and get that information, no matter what
the user has selected for their own logging framework.
I imagine something like:
RegisterLogMonitor(CallbackFunction, LogLevel.Warn, "My.Log.Name")
A similar mechanism should be provided that works with the config
system. The name of the log to watch would be optional.
The callback function would have a signature something like:
CallbackFunction(string logName, LogLevel level, string message,
Exception exception)
Using this lightweight mechanism, programs would be able to register
watchers for certain log event types and presumably the Common.Logging
framework would have some high-performance way to pass along only the
logs that are requested and ignore others. This mechanism would
ignore any logging levels configured for other software. This would
allow somebody who needs to monitor the logs for some programmatic
reason to trust that their needs will be satisfied no matter how users
configure the primary logger.
I started on such an implementation already, but it'd be great to just
use something available in Common.Logging if you have the time to work
on it now.
Patrick Earl
On Aug 4, 7:06 am, "Erich Eichinger" <[email protected]> wrote:
> Hi all,
>
> I am one of the authors of Common.Logging. If you are missing something in
> Common.Logging, please let us know. I already had some discussions around
> Common.Logging+NHibernate with Fabio and Oren long ago, I believe there were
> some needs regarding logging context?
>
> As sourceforge is a big PITA, we recently decided to move over the project
> to github, hopefully encouraging more people to contribute. Also we will
> move the mailinglist and bugtracker, I will communicate the changes asap (by
> the end of next week).
>
> As for introducing an external dependency, I fully understand your concerns.
> 2 thoughts on this:
>
> 1) there seems to be a misconception: When using Common.Logging there is
> only a dependency on Common.Logging, but *no* compile-time dependency on
> log4net. Only if you configure Common.Logging to use log4net (by specifying
> Common.Logging.Log4Net's LoggerFactoryAdapter in App.config) you obviously
> have a *runtime* dependency on log4net.
>
> 2) As for avoiding any dependency on a logging framework at all, I'd love to
> hear any ideas out there how to allow for using a logging framework without
> introducing a compile-time dependency. My only idea would be to hijack the
> existing System.Diagnostics.Trace API, providing TraceListeners for plugging
> in the logging framework of your choice.
>
> As for migrating from log4net to System.Diagnostics, I attached a simple
> POC demonstrating the idea for introducing a log4net-compatible logging
> infrastructure. This should make the migration pretty much a no-brainer.
>
> I plan to conduct some performance-tests as well as tests regarding the
> functional behavior - especially regarding maintaining the correct
> stacktrace in the logs - after moving the project on github to see if this
> idea makes sense. Any feedback is welcome!
>
> hth,
>
> Erich
>
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Fabio Maulo
> Sent: 04 August 2010 11:37
> To: [email protected]
> Subject: Re: [nhibernate-development] Re: Logging Abstraction
>
> We need the Log before start anything else.
>
> The discussion about CommonLogging and custom log was part of that old
> discussion.
>
> I'm inclined to say goodbye to any external reference (including Iesi...
> even if not so "external") but, at this point, for logging we will reinvent
> the wheel.
>
> If, using CommonLogging, we don't loose something important for NH then we
> can use it.
>
> On Wed, Aug 4, 2010 at 12:37 AM, Patrick Earl <[email protected]> wrote:
>
> In order to use log4net with Common.Logging, the
> Common.Logging.Log4Net assembly is required. Is it acceptable for
> users to need to add a reference to Common.Logging.Log4Net to their
> code? If this was unacceptable, the Common.Logging.Log4Net assembly
> could be embedded in the NHibernate assembly directly. It seems that
> the approach taken historically was to document the need for the extra
> assembly reference and not embed anything.
>
> I understand there is also sometimes a need to hook into the logging
> layer independent of the logging provider being used. I propose that
> there be an NHibernate LogManager class that is used all over the
> NHibernate code to get an ILog instance. Providing log interception
> at that point would be a simple matter of creating a class that
> implements ILog and delegates to the underlying Common.Logging manager
> but also throws events when messages are logged. The event mechanism
> would be the same one powering events such as IPostLoadEventListener.
> I assume some of the comments by Ayende were referring to NHProf...
> would this design cover any needs there without significant
> difficulty?
>
> For the start-up configuration, after looking at the code, my best
> interpretation of what Fabio said is that the log initialization code
> should go at the start of BuildSessionFactory (before the call to the
> proxy factory factory config). This would ensure that logging is
> properly enabled during the initialization process.
>
> I've already started re-integrating the old Common.Logging patch into
> the trunk. I will work towards the design proposed here in the mean
> time.
>
> Patrick Earl
>
> On Aug 2, 11:33 am, Fabio Maulo <[email protected]> wrote:
>
> > Solution
> > 1) add common logging
> > 2) at NH startup look for log4net.dll (start-up mean just before
> instantiate
> > the bytecode-provider)
> > 2a) where present autoconfigure common-logging/NH to work with log4net
> > 3) for other logging framework we can just relay to common-logging
> > configuration/restrictions.
>
> --
> Fabio Maulo
>
> LoggingTest.zip
> 1KViewDownload
