Re: [higgins-dev] IdAS changes proposalPaul,
> 1. We define a new .api2 that replaces the IFilter stuff with SPARQL.
Yes, replaces IFilter, removes IBlankEntity, and (perhaps) replaces IModel
interfaces with something you were going to propose.
> 2. We define a sub-set of SPARQL that could be used with .api2 for purposes
> of creating an adaptor CP, yet would still have acceptable performance.
Yes. Also, because SPARQL allows to query literals, I suppose it would be
useful to query as full Entities as separate attribute values. I suppose we
should add two methods to IContext:
a) Iterator getEntities(String sparql) - returns iterator of IEntity;
a) Iterator getValues(String sparql) - returns iterator of List, where list
contains data objects;
> We would implement the full new .api2 in any new CPs that are based on RDF
> technology directly (e.g. Jena) or on something like RDF (e.g. XDI).
Yes.
> We will inform Mary Ruddy ASAP about any new tech (e.g. ARQ or newer versions
> of Jena) we want to use for this new CP so we can get the Eclipse legal
> process going.
Yes, of course.
Thanks,
Sergey Lyakhov
----- Original Message -----
From: Paul Trevithick
To: higgins-dev
Cc: Vadym Synakh ; Paul Trevithick ; Igor Tsinman
Sent: Thursday, October 15, 2009 9:58 PM
Subject: Re: [higgins-dev] IdAS changes proposal
Sergey,
Are you proposing that:
1.. We define a new .api2 that replaces the IFilter stuff with SPARQL.
2.. We define a sub-set of SPARQL that could be used with .api2 for
purposes of creating an adaptor CP, yet would still have acceptable
performance.
3.. We would implement the full new .api2 in any new CPs that are based on
RDF technology directly (e.g. Jena) or on something like RDF (e.g. XDI). [Of
course as you know Jena has an add-on (ARQ) SPARQL processor, so if we use ARQ
+ Jena we're "done" from a raw functionality point of view-we just have to
adapt to the IdAS .api2]
4.. We will inform Mary Ruddy ASAP about any new tech (e.g. ARQ or newer
versions of Jena) we want to use for this new CP so we can get the Eclipse
legal process going.
--Paul
On 10/15/09 12:16 PM, "Sergey Lyakhov" <[email protected]> wrote:
Paul,
Actually, I did mean the following:
1. Main point - it is difficult to implement full SPARQL specification in
Upper CP because it is really difficult task. In other words, we can implement
"restricted" SPARQL functionality where some queries will not work.
2. (as you understood) some semantics can't be expressed in the .api CP
using .api.IFilter. For such queries (where regex() is present for an example)
Upper CP will work solwly.
Thanks,
Sergey Lyakhov
----- Original Message -----
From: Paul Trevithick <mailto:[email protected]>
To: higgins-dev <mailto:[email protected]>
Cc: Vadym Synakh <mailto:[email protected]> ; Paul Trevithick
<mailto:[email protected]> ; Igor Tsinman <mailto:[email protected]>
Sent: Thursday, October 15, 2009 6:41 PM
Subject: Re: [higgins-dev] IdAS changes proposal
Sergey,
Let me see if I understand what you are saying. Are you saying this:
a.. We could implement the .api2 CP as shown below, but it will be
difficult to implement in it many aspects of SPARQL because the semantics
can't be expressed in the .api CP using .api.IFilter.
If yes, then I was thinking was different. I was not assuming that
.api.IFilter semantics were sufficient to express the SPARQL semantics
directly. I was, however, assuming that the upper .api2 CP may in some cases
have to read (using lower .api CP) many, most, and sometimes ALL (!) entities
from the lower .api CP and perform the SPARQL WHERE filtering algorithms
itself. And this is why I was saying that the performance may be very bad when
this two layer approach is taken.
I'm looking for a solution that allows the old .api to be maintained and
to be able to reuse these "old" CPs by adapting them with the upper .api2 CP.
If the performance is too bad, then the developer can implement a "native"
(not two layered) CP using .api2.
--Paul
On 10/15/09 11:27 AM, "Sergey Lyakhov" <[email protected]> wrote:
Paul,
> Do you think it is practical to implement this:
> +----------------------------------------+
> | Upper CP that implements .idas.api2 |
> | SPARQL api but read/writes "raw" |
> | entities/attributes from lower CP |
> +----------------------------------------+
> +----------------------------------------+
> | Lower CP implements existing .idas.api |
> +----------------------------------------+
I think we are able to implement basic aspects of SPARQL which will
satisfy our requirements. However it will be difficult to implement many
aspects of SPARQL such as FILTER functions in WHERE clause (moreover, there is
no any equivalent of those functions in idas.api.IFilter). For example, if I
want to use regex(..) SPARQL FILTER function in Upper CP, I'll need first
select all entities from old CP, and than make additional check selecting
entities which conform to the regexp.
Thanks,
Sergey Lyakhov
----- Original Message -----
From: Paul Trevithick <mailto:[email protected]>
To: higgins-dev <mailto:[email protected]>
Cc: Vadym Synakh <mailto:[email protected]> ; Paul Trevithick
<mailto:[email protected]> ; Igor Tsinman <mailto:[email protected]>
Sent: Thursday, October 15, 2009 4:31 PM
Subject: Re: [higgins-dev] IdAS changes proposal
Sergey,
Hmmm, this is a tough one. We don't want to lose the investments in
the existing CPs (the old .idas.api). Yet we don't want to create a burden
for new CP developers. While we mull this over, I have a question. Do you
think it is practical to implement this:
+----------------------------------------+
| Upper CP that implements .idas.api2 |
| SPARQL api but read/writes "raw" |
| entities/attributes from lower CP |
+----------------------------------------+
+----------------------------------------+
| Lower CP implements existing .idas.api |
+----------------------------------------+
If so, then we could maintain both the lower and the upper APIs.
Any CP that didn't want to support the .api2 (upper api) wouldn't have to,
there because they could use the upper "adapter" CP. The result might be very
slow, but at least it (might) work. And if good SPARQL performance was
required, then the CP would be force to do a native implementation of
.idas.api2.
[One really interesting benefit of implementing SPARQL is that with
the above adapter plus a web service front end, we can expose any IdAS data
source as a SPARQL endpoint. Then we'd have XDI and SPARQL endpoints for the
Attribute Service. The Linked Object Data (LOD) semweb folks are creating
lots of SPARQL endpoints-we'd dovetail with these efforts.
--Paul
On 10/15/09 6:23 AM, "Sergey Lyakhov" <[email protected]>
wrote:
Paul,
Sorry for delay.
> 3. Jim Sermersheim invented IFilter because we needed something
and SPARQL wasn't yet established. Now that it is, I wonder if we shouldn't
give it another look
It would be very convinient to use SPARQL for RDF-based context
providers (like jena CP). However it would be hard to implement all aspects
of SPARQL for context providers which are not based on RDF (JNDI, XML,
Hibernate etc.).
> When you go to make these changes, it will be critical to load
into your workbench every possible context
> provider that you can find so that you can fix them so that
they don't all break.
It will take a lot of work to implement new filter/model for all
providers. So, I suppose there is a sence to put new IdAS interfaces into a
new project (like org.eclipse.higgins.idas.api2) and than fix all providers
to support these new interfaces. What do you think about this?
Thanks,
Sergey Lyakhov
----- Original Message -----
From: Paul Trevithick <mailto:[email protected]>
To: higgins-dev <mailto:[email protected]>
Cc: Vadym Synakh <mailto:[email protected]> ; Paul
Trevithick <mailto:[email protected]> ; Igor Tsinman
<mailto:[email protected]>
Sent: Monday, September 28, 2009 3:11 AM
Subject: Re: [higgins-dev] IdAS changes proposal
Sergey,
My responses:
1.. agree
2.. agree
3.. Jim Sermersheim invented IFilter because we needed
something and SPARQL wasn't yet established. Now that it is, I wonder if we
shouldn't give it another look
4.. (4.1): short answer: no. Longer answer: cdm.owl is an
attempt to approximate in owl concepts that cannot be directly
operationalized in real RDF/OWL based systems. Only higgins.owl should be
imported and used. Cdm.owl is just an attempt at explanation. It can be
ignored. (4.2) A lot of OWL URLS end in .owl, but it isn't a firm
requirement or convention.
When you go to make these changes, it will be critical to load
into your workbench every possible context provider that you can find so
that you can fix them so that they don't all break.
--Paul
On 9/23/09 12:07 PM, "Sergey Lyakhov" <[email protected]>
wrote:
Paul,
I suppose, cdm:entityId is redundant and we can use rdf:ID
instead. As a result:
1.1. In this case IEntity.getEntityID() will retun rdf:ID.
1.2. In case of blank entity (previously known as a complex
value) it should return null.
1.3. entityId attribute will be eliminated.
I suppose we need to do the following changes to IdAS
interfaces to be compatible with CDM:
2.1. BlankEntity class has been eliminated from cdm.owl. So,
I suppose we need to do the same for IdAS interfaces and replace
IBlankEntity with IEntity (eliminate IBlankEntity interface).
Because there is no any difference between entity and
complex value, we can define the following:
2.2. If Entity has been created by
IContext.addEntity(entityType, entityID) method, it should always have
entityID (should not be a blank entity). In other words, a unique value
should be generated by a context and used as entityId, if no entityId
passed.
2.3. If Entity has been created by IAttribute.addValue(URI)
method, it should be a blank entity.
2.4. If Entity has been added by
IAttribute.addValue(IAttributeValue) it should be the same type as passed
entity. If passed entity is a blank entity, new blank entity should be
created as a copy of passed, otherwise a reference to the existent (non
blank) entity should be created.
2.5. When Entity is deleted, all its subentities which are a
blank entity should be deleted too.
Also we need more flex IFilter API:
3.1. IFilter should be able to query both types of entities
as blank as usual.
3.2. IFilter should be able to query a separate value (entity
or simple value) of any nesting level, not only direct attributes of
Entity.
Also I have some notes about CDM:
4.1. CDM.owl contains entityRelation and contextRelation
object properties. Do we need to reflect them in IdAS interfaces?
4.2. Namespase of cdm.owl
http://www.eclipse.org/higgins/ontologies/2008/6/cdm.owl ends with .owl. Is
it correct?
Thanks,
Sergey Lyakhov
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