In a serialized RM instance there is always a field that lets you know what the 
class is, for example standardized as discussed before in xml, and as the field 
_type in json.

If you have this mapped as actual objects in memory in your system, those 
usually have something in place to determine which class an object is. There's 
no need to replace the standard mechanisms with something custom and 

In other words, yes you need to know the class of a given object, but it is 
mapped to the mechanism best suited for the used concepts and technology.


Pieter Bos

Op 10 okt. 2019 12:19 schreef Georg Fette <>:
But if the class is contained within a template instance only within
some technical background information and it is not part of the
reference model, how can a query mechanism like AQL use this information
during query execution ?
How does an AQL query engine know that an archetype based on Composition
is a Composition when this link is given in the RM-part of the
serialized instance only within the archetype_id of the
archetype_details ? From that it could deduced by using the background
knowledge of the available archetype definitions that it is in fact a
Composition. It would be easier if this would be directly included in
the RM-part of a serialized Composition itself.
Or is the class type something one would assume as part of the RM ?

Dipl.-Inf. Georg Fette      Raum: B009
Universität Würzburg        Tel.: +49-(0)931-31-85516
Am Hubland                  Fax.: +49-(0)931-31-86732
97074 Würzburg    

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