[ontoiop-forum] OMS: Structured focused basic distributed query

[Till Mossakowski]

Dear Tara,

>> currently, queries are part of OMS networks (= distributed OMS).
>> I cannot see why they should become part of structured OMS. How would
>> they then affect the model class of the structuted OMS?
> This comes back to what is the defining concept for the term
> "structured OMS".  The name suggests it is simply an OMS with
> structure (whatever that means). There is, I imagine, some
> category-theoretical way to distinguish a structure from a network.
>
agreed.
> Given that we are now allowing OMS which are simply queries, then it
> seems reasonable to me that there could also be queries with
> structure, or hybrid assertion-query OMS with structure.
>
> Here are some use cases, where the relationship between the components
> seem to me to be tighter than what I would expect in an 'OMS network':
> 1. It is not uncommon to have a set of queries.
> For example if a query language does not support disjunction, then
> this may be emulated by applying two queries and taking the 'union' of
> the results.
>
> 2. In certain query languages, query results can depend on the order
> of application, so a sequence of queries is a relevant construct.
>
> 3. Translation between query languages is a reasonable operation to
> support.
>
> 4. I can certainly imagine forming a combination query using multiple
> query languages, dependent on a translation between the query languages.
>
> 5. Query rewriting is a technique developed in the database world that
> may be relevant for querying structured OMS, and, somewhat out of
> scope for OntoIOp, is important for supporting OBDA.
>
> 6. There are a number of languages, especially in the LP realm, that
> allow assertions (and other performatives that modify the theory, such
> as retractions) to be interlaced with queries.
>
OK, but all these (probably except 3.) are structuring operations that
are different from structuring operations for OMS. It seems to me that
we need a seperate structuring language here...

Best, Till