I think this also reiterates the very important need for some sort of 
trace system for event processing / mapping, so we can "step through" a 
test event and our mappings / transforms. I imagine something very like 
a programming debugger or the like.
--
James Pulver
Information Technology Area Supervisor
LEPP Computer Group
Cornell University



jcurry wrote, On 9/4/2009 12:13 PM:
> I have just proved that cascading event processing did indeed arrive with 2.4 
> (strictly it's 2.4.1 that I am using).  However I cannot find any 
> documentation for how it works and certainly no examples as suggested by Matt!
> 
> There are 2 different aspects to consider; event class transforms and event 
> class mapping transforms.
> 
> Pre 2.4, I believe it was relatively simple.  Either a single class transform 
> was used (if no event mapping took place ie event generated by Zenoss 
> daemon), or an event mapping transform took place, in which case any class 
> transform for the resulting class was ignored.  If a class transform was 
> used, it was simply a single transform - no cascading hierarchy of transforms.
> 
> Now life is much more complicated.  Ignore class mapping transforms for a 
> moment.  If you have a class hierarchy /Skills/S1/S2 and each of these has a 
> transform, then, for an event of class /Skills/S1/S2 they are all applied, as 
> Matt says, starting with the Skills transform, then the S1, then the S2.  If 
> a different private field is defined in each, then an event of class 
> /Skills/S1/S2 will end up with all the private fields, a /Skills/S1 event 
> will end up with those fields from /Skills and S1 but not S2, etc.  If the 
> same private field is defined in all the transforms, then the most specific 
> wins ie. S2.
> 
> Now introduce event class mapping transforms.  In the past, if a mapping 
> transform was used, any class transform was ignored.  Now, BOTH the event 
> class mapping and the event class transforms seem to be applied.  Any private 
> field that appears in both, the mapping transform takes precedence - OK so 
> far.
> 
> However, I find that a mapping transform may use a private field from the 
> class transform - so the order is class then mapping???
> 
> But I also find that a class transform can make use of a private field from a 
> mapping transform - so the order is mapping then class???
> 
> So, questions:
> 1) Please where is there some good documentation on the cascading event 
> transforms that arrived in 2.4 but didn't even get a mention in the Release 
> Notes?
> 2) What is the order of processing when you have both mapping transforms and 
> class transforms?
> 3) Or is there something really clever goes on at database insertions time 
> where all this gets sorted out?
> 
> Cheers,
> Jane
> 
> 
>> Matt Ray wrote, On 4/10/2009 4:11 PM:
>> Quote:
>> There are some changes being made to Event Transforms for 2.4. We're
>> working on getting some examples added to the documentation and I
>> don't think they're all in the beta yet. One of the changes will be
>> cascading event transforms. Event transforms are applied down the
>> event hierarchy, so that on an incoming /Business/Service/Bus event,
>> the /Business transform would be applied, then the /Service
>> transform, then the /Bus transform. This sounds like what you want.
>>
>> Thanks,
>> Matt Ray
>> Zenoss Community Manager
>> community.zenoss.com
>> [email protected] 
>>
> 
> 
> 
> 
> 
> -------------------- m2f --------------------
> 
> Read this topic online here:
> http://forums.zenoss.com/viewtopic.php?p=38958#38958
> 
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> 
> 
> 
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