RE: moving along on rules language

[Alex Rousskov <rousskov@xxxxxxxxxxxxxxxxxxxxxxx>]

On Wed, 10 Sep 2003, Anwar M. Haneef wrote:

> I haven't been an active participant on this list, but have worked
> on OPES for a while (2 years) from an academic standpoint. I agree
> with Andre regarding the compactness of the rule expression
> language. The reason for this is because I don't see the need for
> these rules to be interepreted on the fly.

For the record: even if we decide that compactness is not important
for OPES applications, it is not a negative characteristic either.

> On the other hand, Alex's proposed P language seems to entertain a
> more flexible mechanism for expressing expressions. Maybe this is due
> to my lack of experience in languages, but this is one major issue I
> had with developing IRML-based Processing Point rules for content
> delivery based on QoS and device characteristics.

Could you please post an example or two where IRML lacked expression
power you needed?

> Another concern I had regarding P is the relative ease or complexity
> of auto-generation P language rules. For instance, from my previous
> experience (mentioned above), it is relatively simple to generate an
> XML-based IRML rule by parsing a restricted clickable-web form that
> allows users to define their preferences.

I assert that is it equally easy to generate IRML and P rules from Web
forms. Given a form that both languages can support, the code to
generate P or IRML statements would be virtually identical. With P,
the generator MAY perform additional optimizations and/or use
additional form entries, but that is a different story.

> I guess most of these concerns boil down to my apprehensions
> regarding the amount of expertise in the market with XML-parsers as
> opposed to BNF parsers-generators. Should ease of development be a
> criterion ?

I am not sure whether you are saying that there is more expertise with
XML parser generators. If you are, I strongly disagree. Parser
generators existed well before XML and are very well known. In fact,
most XML parsers are written using the knowledge gained from the good
old parsing theory.

> Also, would it be possible to mix the features in IRML and P to
> develop a mechanism by which structure could be defined by the
> XML-based IRML while P syntax is used for expressions,

What would be the benefit of using XML then?

Alex.