[Hawkular-dev] logging ID ranges

[John Mazzitelli]

I would like to make a recommendation for logging range IDs for the different components.

Right now, the default width of IDs are 6 characters (they can be more or less, but that's the default). I'm assuming we all will use HAWK as the prefix (as opposed to HAWK vs. HAWKMETRICS vs. HAWKALERTS, etc).

Through my experience integrating this logging stuff the past few days in the bus modules, I've come to appreciate the fact that we should probably give more range than just 1000 IDs to a major component. I don't know exactly how to do it, but I found it easier to split the ranges up to my subcomponents when using the full 6-characters. This allows you to create multiple MessageLogger classes (one per maven module is what I think would be typical - especially if one module doesn't depend on others) and you can break your main range up into subranges, while still having enough IDs left for actual logs.

For example, suppose metrics has four subcomponents (and I'm just making this up) - metrics-aggregator, metrics-collector, metrics-ui, metrics-purge. Now, suppose metrics was given the range 1000-1999. Each subcomponent would only have 250 IDs each if you assign them their own subrange. If you don't, if you just give them all 1000 then you will probably only have a single MessageLogger for all 4, and that will get ugly (MessageLogger would live in one module, and they all would need to depend on it, and any new log message would require all modules to recompile, even if the other modules don't need that message).

So what I say is we give metrics the ID range (e.g.) HAWK-200000 to HAWK-299999. Each subcomponent could then be given:

metrics-aggregator = 200000-200999
metrics-collector  = 201000-201999
metrics-ui         = 202000-202999
metrics-purge      = 203000-203999

So you can see each still has room for 1,000 message IDs individually with room for 100 subcomponents (that's the first three digits of the ID - 200-299).

Alerts would then be given the range HAWK-300000 to HAWK-399999 and it does the same thing.

Obviously, this can be tweeked; you can say the first two digits are the component (20-29) giving you room for 10 subcomponents, with each subcomponent now able to have 10,000 messages (e.g. 200000-209999).

Or we can give each their own prefix (HAWK vs HAWKMETRICS) giving each the full 6-digit ID range all to themselves.

In any event, if you haven't tried coding up log messages with this Jboss logging message ID stuff, I suggest you do it, and see what kinds of issues you will see crop up (mainly it deals with what ranges of IDs get assigned to what MessageLoggers and how many MessageLoggers do you create and where).

We don't want to do this wrong - it will be headaches later on in the future when we realize we handed out the IDs ranges poorly or we created MessageLoggers in the wrong places.

I'm not advocating any specific approach, but we need to think about this - this isn't one of those things where everyone can go rogue. Unless we give everyone their own id prefix (HAWK vs. HAWKMETRICS, for example) in which case, go crazy :)