[slf4j-dev] Usage of Markers

[Ceki Gulcu]

If we are talking about a small number of markers, they could be
manufactured in a utility class and assigned to constants. Other
classes would simply reference those constant Marker objects. That's a
trivial problem with a trivial solution.

However, if the number of markers are too numerous to be enumerated as
constants, then we need to work a little harder.

Assume the alert data consists of two fields: alertKey and level. You
could create and use a marker as follows:

// merge fields alertKey and level
Marker m = MarkerFactory.getMarker(alertKey+","+level);
logger.info(m, "the aircondition is down);

The above is not very elegant but for a two field structure would
probably work fine. I offhandedly am assuming the the cross product of
alertKey and level is smaller than 1'000.

Also note that markers can be nested. Thus, you could also write

// merge fields alertKey and level
Marker m = MarkerFactory.getMarker(alertKey+","+level);
Marker alertkeyMarker = MarkerFactory.getMarker(alertkey);
if(!m.containts(alertkeyMarker) {
   m.add(alertkeyMarker);
}
Marker levelMarker = MarkerFactory.getMarker(level);
if(!m.containts(levelMarker) {
   m.add(levelMarker);
}
logger.info(m, "the aircondition is down);

This can be refactored as

static Marker myMarkerMaker(String alertKey, int level) {
   Marker m = MarkerFactory.getMarker(alertKey+","+level);
   Marker alertkeyMarker = MarkerFactory.getMarker(alertkey);
   if(!m.containts(alertkeyMarker) {
     m.add(alertkeyMarker);
   }
   Marker levelMarker = MarkerFactory.getMarker(level);
   if(!m.containts(levelMarker) {
     m.add(levelMarker);
   }
   return m;
}

and reduced into two lines per invocation:

Marker m = myMarkerMaker("alert.aircondition", 1);
logger.info(m, "the aircondition is down);

HTH,

Szel, Zoltan wrote:
>>  The issue is in what the benefit is in having Markers for each of the 
> various kinds of alerts
> 
> There would be only one Marker implementation which would contain any 
> information required(alertkey, level1/level2 classification etc) to send 
> an alert. This would allow the flexibility to send different alerts with 
> the same API(they can provide defaults, but it would not be enough given 
> that different infrastructure components will send alerts with different 
> properties).
> 
-- 
Ceki Gülcü
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