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Hi Blaise,
We want to add our thoughts:
- Sequenced Data
Objects
If we imagine, the
data of a DataObject are just the content of the properties and the sequence is
part of the view in the specific projection then we could define the following
quite simple rules:
If
O1.getType().isSequenced()==false and O2.getType.isSequenced()==false,
then just the content of the properties is
important.
If
O1.getType().isSequenced()==true and O2.getType.isSequenced()==false,
then just the content of the properties is important. (The original sequence
is lost after projection, if there is no further
magic.)
If
O1.getType().isSequenced()==false and O2.getType.isSequenced()==true,
then the sequence of O2 has the default order of the properties in
Type2.
If
O1.getType().isSequenced()==true and O2.getType.isSequenced()==true, then
we could define an algorithm that calculates the sequence in O2 after the
projection, e.g.
Copy all
properties that are elements in both types from sequence1 to sequence2 in the
order that is defined in sequence1.
Append all
remaining element properties of Type2 (that are attributes in Type1) in the
default order to sequence2.
- Abstract Types
Agree, an abstract type in the target HelperContext
would prevent the project operation. In detail that means a target type cannot
be abstract and the original type cannot be abstract too.
- Open Types
It depends on whether we will allow hiding of properties. All open
content of a O1 with (O1.getType().isOpen() == true) could be hidden in O2 with
(O1.getType().isOpen() == false).
- Undefined State
The user should be able to determine if
the DataObject is in an undefined
state.
Best
regards,
Ulf &
Stefan.
Hi Ron,
Could you clarify the following issues as they
relate to the project operation below?
DataObject O2 =
C2.getDataHelper().project(O1);
Sequenced Data
Objects
- If O1.getType().isSequenced()==true and
O2.getType.isSequenced()==false (allowed in section 4.5.4), then what is the
impact on O1's Sequence as operations are performed on O2?
- If O1.getType().isSequenced()==true and
O2.getType.isSequenced()==true, then are modifications made to O2's Sequence
reflected on O1's Sequence? Does this include text values
O2.getSequence().addText("foo")? What is the impact if type Types are
not in agreement about which properties correspond to XML elements (included
in Sequence) and XML Attributes (not included in Sequence).
Abstract Types
- Section 4.5.5 indicates that isAbstract() cannot
be used in the determination of Type compatibility. If the Type in the
target HelperContext is abstract won't this prevent the appropriate target
DataObject from being instantiated?
Open Types
- Section 4.5.5 indicates that isOpen() cannot be
used in the determination of Type compatibility. If the open nature of
the Type does not agree then won't the presence of open content properties on
O1 prevent it from being cased to O2
(O2.getType.isOpen()==false)?
Undefined State
- What does it mean for O1 to be in an "undefined
state" after it is casted into C2. Does this mean making calls to O1
will throw exceptions? Can a programmer determine that O1 is in
an "undefined state" state?
Valid DataObjects
Returned
- The last 2 paragraphs of section 4.14.2 state that
O2 must be valid according to the rules of C2 or an exception MUST be
thrown. What is the definition of "valid"? With the current type
compatibility definition is it possible to achieve a reasonable number of
"valid" projections. If an exception is thrown because the projected
DataObject is not valid is it possible to provide the user with enough
information to fix the problem. This isn't such a concern for the
initial projection, but is a concern when trying to reverse the projection to
put O1 back in a "defined" state.
-Blaise
----- Original Message -----
Sent: Thursday, March 20, 2008 9:52
AM
Subject: [sdo] ISSUE 66: Proposed
Resolution
<<ISSUE 66 Proposed
Resolution.doc>>
Hi Everyone,
I've removed references to POJO objects.
Ron
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