I read that classads are schema independent in specifying entity attibutes.
How does classads achieve that?
We don't have a way of specifying a schema, and no schema is checked
when creating or changing a ClassAd. This doesn't prevent a
higher-level of the software from using schemas though.
What is the (computaitonal or storage) cost incurred in achieving
schema independence?
If I understand your question, it's a negative cost. There is no
space dedicated to storing a schema, and no time dedicated to
checking that attributes match a schemea.
ClassAds are not schema free because of computational or storage
costs though: it's a design decision about we want to use ClassAds.
For instance, in Condor users are free to arbitrarily extend Job and
Machine ClassAds and use those extensions for matchmaking without
consulting a central authority for permission to modify the schema.
-alain
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