Andre Beck <abeck(_at_)bell-labs(_dot_)com>, writes:
Hilarie,
> The rules language should not be a programming language - it should be
> a constrained language that can be compiled into efficient runtime
> dispatches. XML seems like a reasonable way to represent rules,
> prior to compilation.
I agree.
> However, I believe that the constraint of triggering only a single
> action is too severe. It is important to be able to specify
> sequencing: e.g., action1, then action2.
I agree again. IRML already supports just that: it lets you specify one
or more OPES services that are to be executed in the specified order.
However, there still has to be a policy that determines how to order
service execution requests from different rule authors.
Or even from the same author? There are many possible policies, but
it might be good enough to say to order them by two metrics: most
specific pre-condition match and specific ordering. Rules can have
ordering metrics of "always first" "always last" "first of equal
specificity", "last of equal specificity".
> I am a proponent of an approach that supports detailed parsing of
> cached content. In this model, the OPES processor would take the
> content-related rule elements and compile them into a single parsing
> routine. This code might run on an OPES helper machine. The OPES
> processor would then attach the parsed attributes to cached items.
> Requests for such items would trigger OPES rules related to requestor
> profiles; the rules would determine which OPES services were to be
> applied to the cached items (such as, delivering an already modified and
> cached item, or applying further customization to such an item, or blocking
> the item).
Would this be a performance optimization for those requests that can be
served from cache? In other words, are you proposing to cache not only
the content but also some aspects of the rule processing results for
that content?
I'm planning on caching results of doing checks of the precondition
clauses. For example, if a precondition is
http:originatingsite =~*.troubletrouble.com
then the cached content may get a tag of
"precondition3881" entered into its "directory" entry (the 3881 is an
arbitrary number assigned to the precondition, thus making the
precondition into a boolean variable).
Hilarie