Re: [classad-users] How classads achieve schema independence

[Alain Roy <roy@xxxxxxxxxxx>]

>   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