Re: Aspect questions?

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 28 Feb 2012 17:27:34 -0500
Message-ID:
<4f4d54d8$0$294$14726298@news.sunsite.dk>
On 2/28/2012 4:59 AM, Arved Sandstrom wrote:

On 12-02-27 10:12 PM, Arne Vajh?j wrote:

On 2/27/2012 1:37 PM, Novice wrote:

Lew<noone@lewscanon.com> wrote in news:jif5gv$ih$1@news.albasani.net:

Novice wrote:

Hmm. Yes, I suppose that makes sense. I need to review the whole
"inherit" aspect of logging but I've been thinking of one logger
equating to one log and that's not right, is it? See, the penny is
dropping....


A logger is an object that writes to a log. There's no essential
reason the ratio should be one to one. Au contraire, just like
everything else in Java it's reasonable to expect multiple pointers to
point to one thing and multiple writers to write to one output.

Let me ask you this. In your favorite windowing OS, don't you have
many programs each of them writing to a screen? Don't they all write
to the same screen? You don't have a separate monitor for each
program, do you?


Of course not; all programs share the same monitor. (Or would share two
if I had a double-headed setup.)

Which is why I'm surprised to see you say "no" when I asked if all of my
classes in all of my projects should write to the same log. Your analogy
suggests that the loggers should all write to the same log. But I know
you wouldn't deliberately be that self-contradictory. So there's a subtle
distinction you're making that I'm not quite seeing....


Typical:
- one logger instance per class
- one log file per app

Note that configuration of log files and other destinations for
logging should not be in the code but in the log config file.


Also typical: _several_ log files per app. The subsystems that comprise
an application may have such different audiences, log levels, log
volume, and log file treatment (rollover policies, compression etc),
among other things, that it simply makes sense to configure logging for
multiple output files. sed/grep/Splunk filtering and so forth only goes
so far; it's sensible to use the logging framework itself to do some of
the heavy lifting too.


I have not seen different log files for different audiences much.

I have seen log file for everything and some other destination for
the higher levels rather frequently.

Arne

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