RE: [sdo] Simple question with (possibly profound?) implications on SDO 3 :-)

[Frank Budinsky <frankb@ca.ibm.com>]

Hi Radu,

I definitely don't want to remove Sequence. What I'd like to do, assuming 
it is really just for XML, is make it more XML-centric - that is, truly be 
the element content (similar to the DOM children) of the DataObject. It's 
close, but not completely that, today.

I agree that as an abstraction, Sequence is a very good name, but the 
problem is that it's not such a good name from an XML-centric viewpoint, 
since in XML Schema sequence means something very different - a statically 
ordered sequence of elements, as opposed to a dynamically modifiable 
sequence of elements.

Frank




Radu Preotiuc-Pietro <radup@bea.com> 
03/17/2008 07:43 PM

To
Frank Budinsky/Toronto/IBM@IBMCA
cc

Subject
RE: [sdo] Simple question with (possibly profound?) implications        on 
SDO 3 :-)






I agree that having a more XML-centric Sequence is needed, but given
that Sequence is a well-defined API in SDO 2.1, people may very well be
depending on it so I think we need to have a very, very good reason for
removing the current Sequence API (by the way, I think the name is
appropriate because it is an API to manipulate the sequence of
properties inside a DataObject).

Radu

On Mon, 2008-03-17 at 13:30 -0400, Frank Budinsky wrote:
> Hi James,
> 
> Thanks for replying. The idea in SDO 3 is simply to allow XSD to be 
> tightly bound to SDO. It's still a goal to keep a simple abstraction, 
but 
> given the importance of the XML use case, we also need to allow 
> implementations to provide full XML fidelity. This is precisely why I'm 
> asking the question about Sequence. I'm trying to understand if Sequence 

> is needed for more than just the XML use case. If not, then I think it 
is 
> 1) poorly named, and 2) shouldn't be "directly" visible form the pure 
> abstract SDO view. I absolutely believe that we need something like 
> Sequence, but if it's only for XML, it can be even more XML-centric. I 
> have a few ideas, in the XML fidelity area, for where I think we should 
go 
> with this, but I first wanted to understand if everyone agrees that 
> Sequence is just needed for XML. 
> 
> So far, your answer, below, and Ron's are confirming that theory. I hope 

> we will have some time to discuss this further in tomorrow's call.
> 
> Thanks,
> Frank
> 
> 
> 
> 
> "James Hart" <James.Hart@roguewave.com> 
> 03/17/2008 11:03 AM
> 
> To
> Frank Budinsky/Toronto/IBM@IBMCA, <sdo@lists.oasis-open.org>
> cc
> 
> Subject
> RE: [sdo] Simple question with (possibly profound?) implications on SDO 
3 
> :-)
> 
> 
> 
> 
> 
> 
> I have always wondered why that api wasn't strictly part of the XMLDas,
> or as the SDO spec likes to do, in the XMLHelper or XSDHelper. 
> 
> However, I thought there was some talk at the F2F about making the XSD
> more tightly bound to the SDO in 3.0 to better define how the SDO Data
> Object supports meta information.  In that case the sequence api, in
> 3.0, makes more sense to me.  Otherwise, I'd say the whole spec defining
> an XMLHelper and XSDHelper does not make sense to me because it handles
> the way data is stored which is a DAS function which the spec points out
> isn't something it should define.  Again, if the XSD way of describing
> the data is being tightly bound to SDO than maybe we want to change
> XSDHelper into MetaHelper so the underlying mechanism can be changed
> later if the SDO doesn't want to follow XSD later.  If the XSDHelper
> interface is defined well enough than I don't think there would be a
> need for an XMLHelper, since the DAS can, and maybe should, be provide
> and defined by third parties.  Thoughts?
> 
> 
>  ~James
> 
> -----Original Message-----
> From: Frank Budinsky [mailto:frankb@ca.ibm.com] 
> Sent: Friday, March 14, 2008 12:15 PM
> To: sdo@lists.oasis-open.org
> Subject: [sdo] Simple question with (possibly profound?) implications on
> SDO 3 :-)
> 
> Hi,
> 
> I've been thinking a lot about sequenced types in SDO lately, and am 
> starting to wonder if anybody knows of a use case for SDO Sequence,
> other 
> than for XML fidelity? Even though the spec tries to explain sequenced 
> types as being something more abstract than just support for accessing
> and 
> manipulating the XML serialization order and mixed text, I can't think
> of 
> any such use cases. If anybody has a compelling example that I'm
> missing, 
> please let me know.
> 
> If it is really only for XML, I think we should consider changing the
> name 
> in SDO 3, because of the fact that XSD sequence and SDO sequence are 
> almost the opposite of each other (i.e., an XSD type that is simply an 
> xsd:sequence of elements is NOT a sequenced type in SDO). Also, if 
> Sequence is really just an XML thing, getSequence() may not really
> belong 
> in the DataObject interface, and/or perhaps it should be an optional 
> feature in SDO 3.
> 
> Thoughts?
> 
> Thanks,
> Frank.
> 
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