Please find quick comments
From: Blaise Doughan
Sent: mardi 17 février 2009 15:20
To: Christophe Boutard
Subject: Re: [sdo] ChangeSummary presentation
Some early comments:
Slide 4 - The upcoming DAS...
"DAS can be seen as the main consumer for ChangeSummary"
I disagree with this statement. DAS owned DataGraph and at a time
DataGraph was the sole owner of ChangeSummary, when DataObjects were given the
ability to have ChangeSummary properites then SDO users developed their own
uses for ChangeSummary (based on a diff for the graph). I think we're
starting off on the wrong foot to break backwards compatibility here.
For sure I agree that SDO users
can make their own use of the ChangeSummary. The only thing I’m saying is
that performing a kind of dirty tracking in a disconnected model that can be
mapped to any datasource is a very important use case.
In that way we have to be sure
that nothing defined for ChangeSummary in SDO prevent to use it in DAS.
Slide 8 - How does it work? (2/2)
"At XML serialization time, orphan objects are added to orphan
properties and then belong to the containment tree"
How I read this is XML serialization now involves 2 passes. The first is
to determine who the orphans are, the second to actually do the XML
serialization. SDO 3.0 XML serialization will therefore be slower than
SDO 2.1/2.1.1 XML serialization.
It is true but:
If you only deal
with SDO 2.1.x data graphs (pure containment trees) nothing changes.
If you want to be
able to use the new SDO 3 capabilities for dealing with non closed graphs, I
tend to say that it becomes acceptable (IMO). For sure XML serialization can be
slower but it does more.
Slide 18 - Objectives
"Make events recorded in the ChangeSummary more easily usable by a
Persistence solutions work quite well knowing the only the diff in a graph
(current ChangeSummary definition). I believe the objective being
proposed is make the events in the ChangeSummary directly usable by a DAS
(i.e. a delete means remove the item from the database, as opposed to JPA
that interprets the difference in the graph and based on the mapping metadata
decides how to act).
You got my point ;-)
Slide 23 - How to track "Moves"?
Isn't this what is currently done today in SDO 2.1/2.1.1?
Not sure I understand. The idea here is to ensure that
things are clearly explained in the spec and mainly specifies how to deal with
non containment references to objects that are not contained in the “containment
Christophe Boutard wrote:
Please find the presentation for the ChangeSummary
Development Manager, Data Services
Phone: +33 (0)1 46 14 13 06 | Fax:
+33 (0)1 46 14 13 01
21 rue des Trois Fontanots | 92000 |
Nanterre | France
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