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From Daniel Kulp <dk...@apache.org>
Subject Re: Fwd: Logging framework
Date Tue, 18 Sep 2007 14:55:42 GMT

On Tuesday 18 September 2007, Guillaume Nodet wrote:
> On 9/18/07, Daniel Kulp <dkulp@apache.org> wrote:
> > It really IS that simple.   All of the create logger calls go
> > through LogUtils.createl7nLogger, thus, the issue of the factory is
> > irrelevant. Those methods become the factory.    In the log4j impl,
> > it creates a subclass of Logger that wraps the log4j logger and
> > forwards the log and isLoggable methods to the log4j versions.  
> > It's very simple to do. Lars had it stubbed May 2006 for Yoko.
> >
> > The "mixes concern like logging and configuration" part is
> > irrelevant from my standpoint.   The target logging platform should
> > also map those if they care about them.
>
>  It will work provided that:
>   * everybody use LogUtils.createl7nLogger() method

Which is easily enforced with Checkstyle.   Not a big deal.

>   * nobody use Logger.setLevel() in the code

Why?   Log4j certainly supports it.  You would just need to do:

public void setLevel(Level l) {
    super.setLevel(l);
    log4jLogger.setLevel(mapToL4j(l));
}

>   * nobody use Logger.addHandler()

Or the log4j wrapper can wrap the handlers with whatever it needs and do 
the right thing.    First impl could probably ignore it (or throw 
UnsupportedOperation) as I doubt it's called anywhere.


>   * the new Logger implementation has to override all the log, logp,
> logrb, entering, exiting, throwing, severe, warning, info, config,
> fine, finer, finest, addHandler methods (they all check the level
> before calling log, so you need to bypass these checks)

You probably wouldn't need to.   In the constructor, do something like:

public Log4JLogger(....) {
   super(...);
   log4jLogger = ........
   super.setLevel(mapToJUL(log4jLogger.getEffectiveLevel()));
}

so the level that they are comparing to is the appropriate one.    They 
would then only need to override the log(LogRecord) method.   


> As a class inside cxf/commons with log4j as an optional dependency ?
> But if we go this way, i would rather wrap slf4j so that a user can
> easily choose its own logging framework.

Well, slf4j has it's own issues.   It doesn't support the ResourceBundle 
stuff that we completely rely on.   It also has one less logging level, 
but not a huge deal.  


Dan



> Sounds like creating a pluggable logging framework that would use
> java.util.logging as an api ?  What a nice idea ;-)
> But if that's the way to go ...  I'll write it.
>
>
> Dan
>
> > On Tuesday 18 September 2007, Guillaume Nodet wrote:
> > > ---------- Forwarded message ----------
> > > From: Guillaume Nodet <gnodet@gmail.com>
> > > Date: Sep 18, 2007 9:14 AM
> > > Subject: Re: Logging framework
> > > To: Daniel Kulp <dkulp@apache.org>
> > >
> > > I thought about that.
> > > The only problem is that Logger is a class and its own factory
> > > (thanks for extensibility design).  It also mixes concern like
> > > logging and configuration.  Keeping the Logger class does not
> > > ensure which methods are used in the CXF code base.
> > > We can implement our own LogManager to create our derived
> > > Logger, but this is a system global variable to configure, which
> > > means it has side effect on all the VM :-(
> > > Also, it does not work because the LogManager is initialized
> > > only once when the logging system is initialized, which means
> > > that when CXF is loaded, it may already be too late to set our
> > > own LogManager.
> > > I wish your idea could work, that would be much easier...
> > >
> > > On 9/18/07, Daniel Kulp <dkulp@apache.org> wrote:
> > > > Guillaume,
> > > >
> > > > All creation of Logger      objects now go through the
> > > > LogUtils.createL7nLogger(...) calls.   Thus, IMO, you should
> > > > just update those two methods to wrapper things like Log4j with
> > > > something that implements the Logger interface and return that. 
> > > >  That would be the lowest impact on existing code, we could all
> > > > still use the j.u.l API's, etc... (except we need to make sure
> > > > to create the loggers through LogUtils, which we should anyway
> > > > for i18n reasons.)
> > > >
> > > >
> > > >
> > > > Dan
> > > >
> > > > On Monday 17 September 2007, Guillaume Nodet wrote:
> > > > > It seems CXF logging uses java.util.logging, which is fine
> > > > > for a standalone product, but not so fine when integrating CXF
> > > > > inside another product (thinking about geronimo, servicemix,
> > > > > etc...). The main problem is that lots of products uses log4j
> > > > > or another logging mechanism, and not being able to integrate
> > > > > and use the same logging mechanism is imho a real pain for
> > > > > users who want to debug and see what happens.
> > > > >
> > > > > I'm thinking about creating a interface
> > > > > org.apache.cxf.common.logging.Logger that would be used
> > > > > instead of the java.util.logging.Logger class.  The LogUtils
> > > > > helper class would reuse a default implementation using
> > > > > java.util.logging, while other products could implement their
> > > > > own version to wrap their preferred logging api.
> > > > >
> > > > > Thoughts ?
> > > >
> > > > --
> > > > J. Daniel Kulp
> > > > Principal Engineer
> > > > IONA
> > > > P: 781-902-8727    C: 508-380-7194
> > > > daniel.kulp@iona.com
> > > > http://www.dankulp.com/blog
> > >
> > > --
> > > Cheers,
> > > Guillaume Nodet
> > > ------------------------
> > > Blog: http://gnodet.blogspot.com/
> >
> > --
> > J. Daniel Kulp
> > Principal Engineer
> > IONA
> > P: 781-902-8727    C: 508-380-7194
> > daniel.kulp@iona.com
> > http://www.dankulp.com/blog



-- 
J. Daniel Kulp
Principal Engineer
IONA
P: 781-902-8727    C: 508-380-7194
daniel.kulp@iona.com
http://www.dankulp.com/blog

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