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From Nicholas Duane <nic...@msn.com>
Subject Re: Injecting properties into LoggingEvent
Date Sun, 23 Oct 2016 14:03:25 GMT
Is there a way for me to add properties to a LoggingEvent without the user doing anything out
of the ordinary.  Maybe it's even best to assume an existing application which is using log4net.
 I would like to take this existing log4net application and without them changing any code,
configuration changes are ok, I would like to add properties to each LoggingEvent which is
created from their log statements like:


logger.Error();

logger.Info();

logger.Debug();

etc.


such that I could use the PropertyFilter filter to filter out events?  I want to set a property
based on the level of the event.  I could of course use the LevelRangeFilter but in other
cases I'm using the PropertyFilter and was figuring it might be nice to do it the same for
all events.


This other case where I'm using the PropertyFilter is for new events we've introduced.  These
are what we call "compliance" and "business" events.  We originally introduced a "compliance"
event and at that time I introduced a custom level for that.  However, I'm trying to move
away from defining custom levels and instead use a property on the event to distinguish its
"category".  For these new events which don't fit nicely into the level gradient I've introduced
a method for developers to use to log them called LogEvent().  They will pass in their logger,
the category of the event, and the event.  In this scenario it's easy for me to set properties
on the LoggingEvent.  However, for what we call the diagnostic events, those that are logged
using the methods exposed by log4net, we don't want them to have to do anything different
than they were doing.  If they want to log an error they would still use:


logger.Error("this is my error");


or a warning:


logger.Warn("this is my warning");


etc.


Ideally I would like to set the "category" on those events also so that by the time they make
it to the appender it has this "category" property.  Is there a way to do that?


Thanks,

Nick

________________________________
From: Dominik Psenner <dpsenner@gmail.com>
Sent: Sunday, October 23, 2016 9:18 AM
To: Log4NET User
Subject: Re: Injecting properties into LoggingEvent


Sorry, I cannot grasp your requirements. Please try to explain your usecase better in a way
that gives the document some kind of structure.

On 23 Oct 2016 12:02 a.m., "Nicholas Duane" <nickdu@msn.com<mailto:nickdu@msn.com>>
wrote:

Thank you for the suggestions.


We are already logging complex objects in many cases.  We have the notion of a compliance
event.  That's basically a map (IDictionary<string, object>).  We're now adding business
events.  However, even with these "complex" events I don't want the map to contain the category,
at least not at event creation time.  I see an event as just a collection of properties. 
The act of logging it at a certain level or category is what assigns the severity or category.
 For example:


logger.Warn("this is my warning message");


logger.Error("this is my error message");


logger.Info("this is my info message");


In each of those cases if we assume the event is the message itself, there is no criticality
associated with that event.  It's the act of logging that defines the event's criticality.
 I want the same to be true for the category.  I believe I have this working fine for our
"complex" events which don't fit into the Level gradient.  I expose a LogEvent() method which
logs at the Emergency level as I showed in the code I included in the previous thread.  However,
we also need to capture diagnostic events, ones that are logged via the logging framework's
methods:


logger.Error(...);

logger.Warn(...);


What I am hoping to do is hook in some of my code and generate one of our complex events each
time the logging framework logs an event and will map the level to one of our categories.
 I can imagine that this might be possible if I somehow wrap a logger, but as I mentioned
I don't want the user to have to call anything special at startup to hook up that wrapping.
 I was hoping there would be a way for me to hook myself in via configuration.  I'm ok with
giving them a configuration file they need to use but I don't want them to have to change
any existing code them may have.


By the way, we did generate a custom log level for our compliance event.  However I'm trying
to move away from that as it was point out that our events don't fit well within the level
gradient.  So the new code for logging a compliance event does not use that level.  Both the
compliance and business event would be logged at the Emergency level.  I would use the category
property to differentiate them.  Similar, I guess, to log4j2's Markers.


Thanks,

Nick


________________________________
From: Dominik Psenner <dpsenner@gmail.com<mailto:dpsenner@gmail.com>>
Sent: Saturday, October 22, 2016 1:29 PM
To: Log4NET User
Subject: Re: Injecting properties into LoggingEvent


What I am proposing here are a mere ideas that will need further investigation. I have not
tried any of these ideas. You will have to prioritize these ideas based on your requirements.

A. Implement an extension class for the ILog interface
B. Implement a custom ILog interface implementation and a LoggerFactory.
C. Define custom loglevels
D. Use thread context properties altogether with custom format layouts
E. Log "complex" classes that hold your category information and find a way to format them

There might be more things that you could do..

On 22 Oct 2016 5:31 p.m., "Nicholas Duane" <nickdu@msn.com<mailto:nickdu@msn.com>>
wrote:

Is there a way for me to inject properties into a LoggingEvent?  I'm trying to accomplish
this without the user (of log4net) doing anything special.  The only thing I could think of
was wrapping loggers, and while I'm not against doing that it would have to be done via configuration
as I don't want the user to have to do it programmatically.  Is there any way for me to inject
a logger wrapper via configuration?


The reason I'm looking to do this is that I would like to set a property on the LoggingEvent
to use for filtering.  This property would be determined based on the level property.  I could
simply use the level property for filtering, but I have other events which I generate which
are all logged at the Emergency level but have a different value for this property so for
them I'm using this property for filtering.  I don't have the same issue with these other
events because they are logged via an extension method I provided on the ILog interface:


public static class Logging

{

    public static void LogEvent(this ILog logger, Category category, IEvent evnt)

    {

        if ((category != null) && (evnt != null))

            {

            evnt.SetCategory(category.Name);

            LoggingEvent le = new LoggingEvent(null, logger.Logger.Respository,

                    logger.Logger.Name<http://logger.Logger.Name>, Level.Emergency,
evnt, null);

            le.Properties["category"] = category.Name;

            logger.Logger.Log(le);

            }

    }

}


So for instance when a user does the following:


logger.Error("this is my error message");

or

logger.Warn("this is my warning message");

or

logger.Info("this is my info message");


I would like to set the property "category" on the LoggingEvent to "criticalDiagnostic". 
When they do:


logger.Debug("this is my debug message");

or

logger.Trace("this is my trace message");


I would like to set the property "category" on the LoggingEvent to "noncriticalDiagnostic".
 Any way for me to do that automagically?


I also posted this at:


http://stackoverflow.com/questions/40187597/injecting-properties-into-log4nets-loggingevent


Thanks,

Nick

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