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From Ralph Goers <ralph.go...@dslextreme.com>
Subject Re: approach for defining loggers
Date Wed, 09 Sep 2015 02:24:32 GMT
Can you please clarify, “If we had some way to know an event is a business event we wouldn’t
need level”?  I do not understand how you can code logger.log(BUSINESS, msg)  but you cannot
code logger.info(BUSINESS, msg).


> On Sep 8, 2015, at 6:09 PM, Nicholas Duane <nickdu@msn.com> wrote:
> I looked over that stackoverflow post and I'm still not seeing a good match as a way
for us to log our business events.
> A business event I guess is an event which extends whatever schema we come up with for
a business event.  While an instance of this schema could be logged at any level, that really
doesn't make sense in our scenario, regardless of whether some marker was supplied.  If we
had some way to know an event is a business event we wouldn't need level.  We could of course
add some property to our schema which indicates the 'category' of the event, 'business' being
one such category.  Instead we were thinking we could just use level to indicate that an event
is a business event.
> As I mentioned, we're looking to capture 'trace' level events to one store, 'info' -
'fatal' level events to another store, and 'business' events to yet another store.  For 'trace'
and 'info' - 'fatal' it seems reasonable to filter on level within the appender to get those
events to the appropriate location.  It seemed reasonable to do something similar for 'business'.
> I also looked into the EventLogger but not sure that's appropriate.  For one we lose
the granularity to control a specific piece of code from generating business events.  This
is most likely a non-issue as I have mentioned that we don't want to turn business logging
off.  The other is that we lose the name of the logger as it would be the same for everyone.
 Not sure this is that big a deal either as I guess you might be able to capture component
name, though I would rather distinguish using logger name.
> Thanks,
> Nick
>> From: ralph.goers@dslextreme.com
>> Subject: Re: approach for defining loggers
>> Date: Mon, 7 Sep 2015 20:39:11 -0700
>> To: log4j-user@logging.apache.org
>> I still don’t understand why you don’t want to use Markers. They were designed
exactly for the use case you are describing.  
>> You might set retention policies for debug vs info, error and fatal, but a BUSINESS
marker could cross-cut them all.  That is exactly why it is NOT a level. IOW, it gives you
a second dimension for filtering. Ceki invented Markers when he created SLF4J. For his point
of view see http://stackoverflow.com/questions/16813032/what-is-markers-in-java-logging-frameworks-and-that-is-a-reason-to-use-them
>> Ralph
>>> On Sep 7, 2015, at 5:54 PM, Nicholas Duane <nickdu@msn.com> wrote:
>>> If I'm attempting to control all the logging from the configuration and I don't
know the complete set of loggers in my application as there could be 100's or 1000's, wouldn't
it be hard to separate events based on loggers?  It would seem much easier to separate events
based on level.  In addition, level might be a more reasonable approach for separating.  For
example, if I want to send all events to some big-data backend I might want to separate out
traces and debug from info to fatal as traces and debug are most likely less important from
a systems management aspect.  My retention period for traces and debug might be just a couple
days.  The retention period for info to fatal could be 30 days.  Business level might be 2
years.  Any system management notifications would probably be driven off of info to fatal
events and not trace and debug events, which is another reason you might want to separate
by level.  
>>> Thanks,
>>> Nick
>>>> Subject: Re: approach for defining loggers
>>>> From: ralph.goers@dslextreme.com
>>>> Date: Mon, 31 Aug 2015 08:50:58 -0700
>>>> To: log4j-user@logging.apache.org
>>>> A logging “Level” is a level of importance. That is why there is a hierarchy.
If you want informational messages then you also would want warnings and errors.
>>>> “BUSINESS” does not convey the same meaning.  Rather, it is some sort
of category, which is what Markers are for.
>>>> Using the class name as the logger name is a convention. If you really want
the class name, method name or line number then you should be specifying that you want those
from the logging event, rather than the logger name.  Unless location information is disabled
you always have access to that information.
>>>> In short, different loggers are used primarily as a way of grouping sets
of messages - for example all org.hibernate events can be routed to a specific appender or
turned off en masse. Levels are used to filter out noise across a set of logging events. Markers
are used to categorize logging events by arbitrary attributes.
>>>> Ralph
>>>>> On Aug 31, 2015, at 8:10 AM, Nicholas Duane <nickdu@msn.com> wrote:
>>>>> Thanks for the feedback.  I will look into Markers and MDC.
>>>>> With respect to using a separate logger, it would seem I would lose the
information about what application code, eg. the class logger, is sourcing the event.  We
would like to have this information.  On top of that, it seems odd, maybe to me only, that
for this new level we have our own logger.  It seemed reasonable to me that this new event
we want to capture is just a new level.  Just like a DEBUG event is different from an INFO
event.  If I define a BUSINESS level why would that not follow the same design as the current
levels?  You wouldn't suggest having different loggers for TRACE DEBUG INFO WARN ERROR FATAL,
would you?  I think one of the reasons someone on our side is suggesting I have separate loggers
is that they think the overhead of filtering at the appender is going to have a noticeable
impact.  Our plan, at least the one I have now in my head, is that we'll have some number
of appenders in the root.  We'll then filter x < INFO events to a tracing appender, INFO
<= x <= FATAL to a logging appender, and our custom level will go to another appender.
>>>>> Thanks,
>>>>> Nick
>>>>>> Subject: Re: approach for defining loggers
>>>>>> From: ralph.goers@dslextreme.com
>>>>>> Date: Sat, 29 Aug 2015 20:59:36 -0700
>>>>>> To: log4j-user@logging.apache.org
>>>>>>> On Aug 29, 2015, at 7:44 PM, Nicholas Duane <nickdu@msn.com>
>>>>>>> I'm curious if there is a prescribed approach to defining loggers.
 Let me state what my assumption is.  I assume that normally if some piece of code wants to
log events/messages that it should create a logger for itself.  I guess a reasonable name
to use is the class name itself.  In terms of logger configuration I would expect that no
loggers are specified in the log4j configuration UNLESS is needs settings other than the default.
 The root logger would specify the default settings, eg. level and appenders.  If some piece
of code tied to a logger needs to enable tracing in order to debug an issue then you would
add that logger to the configuration and set the level less specific for that logger.  Is
this a typical and reasonable approach?
>>>>>> What you describe here is the common convention. It is a reasonable
>>>>>>> I asked because we have the need for a new type of event.  To
have this event flow to where we want it to flow the plan is to have a custom level and have
all events at that level captured by a specific appender.  My assumption was that for existing
applications we'd just need to add our appender to the root and add our custom level.  The
app would need to be modified to log our new event at the custom level.  However, someone
suggested that we could also create a separate logger for this event.  My thinking is that
while we don't ever want to turn off logging of this event, loggers represent "event sources",
e.g the code raising the events and thus having multiple different pieces of code use the
same logger wouldn't allow you to turn on/off logging from those different sections of code
independently.  I think the current configuration includes all the loggers.  Normally I would
expect there to be many, on the order of 10's or 100's, loggers within an application.  However,
in the case I was given there were only a handful because I think this handful is shared.
 So as I mentioned, this doesn't sound like an ideal design as you have less granularity on
what you can turn on/off.
>>>>>> You have a few options. Using a CustomLevel would not be the option
I would choose.  Creating a custom Logger will certainly work and makes routing the message
to the appropriate appender rather easy.  Another approach is to use Markers.  Markers are
somewhat hierarchical so you can use them for a variety of purposes.  If you look at how Log4j
handles event logging it actually does both - it specifies EventLogger as the name of the
logger to use and it uses Markers to identify the kind of event.
>>>>>> A third option is to use the MDC or Logger properties. If you do
that then you can have information included in the actual logging event that can affect how
it is routed. I also built a system that uses the RFC5424 format so that the event could have
lots of key/value pairs to identify the events.
>>>>>> Unfortunately, without knowing more details I don’t know that I
can give you a better idea on how I would implement it.
>>>>>> Ralph
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