Re: AW: [sdo] Update of remaining XML Fidelity duplicate names issues

[Blaise Doughan <blaise.doughan@oracle.com>]

Hello All,

Attached is the Oracle proposal addressing the following SDO issues:

• SDO-67 Handling of Namespace in SDO Path (section 2.1.4)
• SDO-71 SDOPath handling of '@' character (section 2.1.1)
• SDO-83 Clarification of special "value" property and how to avoid name clashes (section 2.1.5)

-Blaise

Frank Budinsky wrote:

OF9224C73F.E919DDEF-ON852574AB.006610D9-852574AB.00687583@ca.ibm.com" type="cite">

Hi guys,

The current status of at least SDO-67 is that we're waiting to evaluate a 
counter proposal from Oracle. I'm not sure if it will also address SDO-71 
(or SDO-83, which the current SDO-71 proposal also solves). If so, we need 
to see this proposal and evaluate it ASAP. Otherwise, I'd like to suggest 
making SDO-71 an optional feature. All that's needed for that is to 
"allow" SDO names to include the '@' character after which IBM, or anyone 
else that wants to, could implement SDO-71 as described below, and still 
be spec compliant.

The final issue below, SDO-82, is unrelated. Are there any objections to 
that proposal? If not, can we at least resolve it?

It looks like our tentative plan to publish a CD by the end of August is 
becoming highly unlikely. I think we need to put a greater sense of 
urgency on making progress on this spec, or I feel that SDO 3 may come 
unravelled.

Comments?

Thanks,
Frank




"Barack, Ron" <ron.barack@sap.com> 
08/11/2008 06:32 AM

To
Frank Budinsky/Toronto/IBM@IBMCA, <sdo@lists.oasis-open.org>
cc

Subject
AW: [sdo] Update of remaining XML Fidelity duplicate names issues






Hi Frank

I like these proposals.  Two comments, additions.

First, I would like to go through the document and take out all text 
stating that name conflicts must be resolved by annotating with sdo:name. 
We are now allowing duplicate SDO names, and specifying the behavior.

Second, when dealing with name conflicts, I would rather avoid explicitly 
requiring name mangling.  I would rather say that the e.g., attribute 
names must never hide element names.  This is the behavior that is 
interesting for the user.  Name mangling is an implementation detail in 
order to achieve this.  Your wording for proposal 3 is actually already 
what I have in mind, and I would like similar wording in proposal 2.


Ron

-----Ursprüngliche Nachricht-----
Von: Frank Budinsky [mailto:frankb@ca.ibm.com] 
Gesendet: Freitag, 8. August 2008 22:02
An: sdo@lists.oasis-open.org
Betreff: [sdo] Update of remaining XML Fidelity duplicate names issues

Hi Guys,

I've updated the 4 remaining unresolved duplicate name proposals, to 
reflect the discussions/feedback so far.

The remaining issues are (see also section 2.1 in 
http://www.oasis-open.org/committees/download.php/26722/SDO_XML_Issues.doc
):

1. SDO-67 Handling of Namespace in SDO Path (section 2.1.4)
2. SDO-71 SDOPath handling of '@' character (section 2.1.1)
3. SDO-82 Name conflicts with anonymous XSD types (section 2.1.2)
4. SDO-83 Clarification of special "value" property and how to avoid name 
clashes (section 2.1.5)

I'd like to further discuss and hopefully vote on these proposals during 
next weeks TC call.

Thanks,
Frank


PROPOSAL 1. SDO-67 Handling of Namespace in SDO Path (section 2.1.4)

The resolution to this issue is to extend the SDO Path syntax to support 
the namespace-uri() function from standard XPath. Although the syntax is 
somewhat ugly, it's important to not invent our own syntax, but instead 
conform to the original goal of SDOPath which was to be (mostly) a 
compatible subset of proper XPath. 

Given the following schema:

    <xsd:complexType name="TwoBars">
        <xsd:sequence>
            <xsd:element name="bar" type="xsd:string"/>
            <xsd:element ref="tns2:bar"/>
        </xsd:sequence>
    </xsd:complexType>

An SDO user can then retrieve the second "bar" property as follows:

dataObject.get("bar[namespace-uri()='http://the-tns2-namespace']");

As in previous versions of SDO:

dataObject.get("bar");

would continue to return the first "bar".

The specific change to the SDO 2.1 spec is in section 12, change:

step ::= '@'? property
      | property '[' index_from_1 ']'
      | property '.' index_from_0
      | reference '[' attribute '=' value ']'
      | ".."

to the following:

step ::= '@'? property
      | property '[' index_from_1 ']'
      | property '.' index_from_0
      | property '[' namespace-uri() '=' uri ']'
      | reference '[' attribute '=' value ']'
      | ".."

uri ::= '"' anyURI "'" 
      | "'" anyURI "'"


In addition to the above resolution, Stefan has proposed adding the 
following methods to XSDHelper:

XSDHelper.getProperty(Type type, String uri, String xsdName, boolean 
isElement)
XSDHelper.getInstanceProperty(DataObject, String uri, String xsdName, 
boolean isElement)

These methods provide a non-SDOPath alternative for handling this issue as 

well as SDO-71. I'm also OK with adding these methods.


PROPOSAL 2. SDO-71 SDOPath handling of '@' character (section 2.1.1)

TestCase in ZIP file: DuplicateNamesTest.testAttributeElementClash()

The resolution to this issue is to require implementations to 
automatically mangle the name of attributes that conflict with an element 
in a type, and to also specify that XSD attributes will map to properties 
that have @name as an aliasName.

Given the following schema:

    <xsd:complexType name="TwoFoos">
        <xsd:sequence>
            <xsd:element name="foo" type="xsd:string"/>
        </xsd:sequence>
        <xsd:attribute name="foo" type="xsd:int"/>
    </xsd:complexType>

This will produce an SDO Type named "TwoFoos" with two properties:

1. name="foo", type=String
2. name="some_mangled_name", type=Int, aliasName="@foo"

An SDO user can then retrieve the foo element as follows:

dataObject.get("foo");

And the foo attribute like this:

dataObject.get("@foo");

Although this solution is not 100% backwards compatible (i.e., it does not 

allow an XML element to be accessed using the "@name" syntax), it is 
backwards compatible for all practical purposes, since it's highly 
unlikely that there are any existing SDO users that rely on the ability to 

use the @ syntax to retrieve element properties.

Note 1: with this proposal, an attribute-backed property that appears 
after an element-backed property in the getProperties() list does not 
necessarily conflict, since the spec already says that in the case of 
duplicates the first property will hide the others. Since the goal of this 

resolution is to ensure that the element-backed property will always take 
precedence we could allow an implementation to choose not to actually 
mangle the attribute-backed property name in this case, as long as it 
still sets the aliasName as specified above.

Note 2: with this solution SDO Path works with SDO names. The 
attribute/element aspects only impact the mapping from XSD to SDO. 

The specific changes to the SDO 2.1 spec for this issue are:

1) In section 9.3 change:

If elements and attributes within a complexType, and its base types, have 
the same local name then unique names must be assigned by sdo:name. 

to the following:

If elements and attributes within a complexType, and its base types, have 
the same local name and unique names are not assigned by sdo:name, then an 

implementation will automatically rename the attribute property (i.e., the 

one for which XSDHelper.isAttribute returns true) to an 
implementation-dependent mangled name. 

(NOTE, do we want to open another issue to consider standardizing the 
mangled name used for conflicting attributes? Personally, I think that if 
users care, they should use sdo:name annotations.)

2) In section 9.3.1, first row of the table (i.e., "Attribute" row), 
change:

Property name=[NAME] 
  type=[TYPE]

to the following:

Property name=[NAME] 
  type=[TYPE]
  aliasName=@[NAME]

3) In section 12, change:

step ::= '@'? property
      | property '[' index_from_1 ']'
      | property '.' index_from_0
      | reference '[' attribute '=' value ']'
      | ".."
property ::= NCName      ;; may be simple or complex type
attribute ::= NCName     ;; must be simple type
reference :: NCName      ;; must be DataObject type

to the following:

step ::= property
      | property '[' index_from_1 ']'
      | property '.' index_from_0
      | reference '[' attribute '=' value ']'
      | ".."
property ::= sdoName      ;; may be simple or complex type
attribute ::= sdoName     ;; must be simple type
reference ::= sdoName      ;; must be DataObject type
sdoName ::= '@'? NCName

Also in section 12, change:

The presence or absence of the @ sign in a path has no meaning. Properties 

are always matched by name independent of their XML representation.

to the following:

Unlike standard XPath, the @ sign is not required for accessing 
attribute-backed properties. It can be used to access properties that have 

an aliasName that includes the @ sign, typically XML attributes - see 
section 9.3.1.


PROPOSAL 3. SDO-82 Name conflicts with anonymous XSD types (section 2.1.2)

TestCase in ZIP file: DuplicateNamesTest.testAnonymousTypeClash()

This issues has already been partially resolved in SDO 2.1.1 (JSR 235). In 

JSR 235 it was agreed that anonymous types in locally defined elements are 

automatically mangled so as not to conflict with global types. For 
example:

    <xsd:complexType name="personRoot">
        <xsd:sequence>
            <xsd:element name="person">
                <xsd:complexType>
                    <xsd:sequence>
                        <xsd:element name="identifier" type="xsd:string"/>
                    </xsd:sequence>
                </xsd:complexType>
            </xsd:element>
        </xsd:sequence>
    </xsd:complexType> 

Unlike SDO 2.1, in SDO 2.1.1 the anonymous type declared under the local 
"person" element will not conflict with a global type "person" such as:

    <xsd:complexType name="person">
        <xsd:sequence>
          <xsd:element name="firstName" type="xsd:string"/>
          <xsd:element name="lastName" type="xsd:string"/>
        </xsd:sequence>
    </xsd:complexType>

However, in JSR 235 it was not required that an implementation also mangle 

the name of an anonymous type under a global element:

    <xsd:element name="person">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element name="name" type="xsd:string"/>
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>

The proposed resolution to this issue is to take the extra step to say 
that the name of this anonymous type must also be mangled. This is 
required in order for SDO to guarantee that:

typeHelper.getType(NS_DUPLICATES, "person");

will always return a real globally defined complexType, as above.

The specific change to the SDO spec for this issue is:

1) the changes to reflect the resolution of the issue in JSR 235
2) State clearly that anonymous types (under local or global 
elements/attributes) will never be given name that hides a globally 
defined type with the same name.


PROPOSAL 4. SDO-83 Clarification of special "value" property and how to 
avoid name clashes (section 2.1.5)

TestCase in ZIP file: DuplicateNamesTest.testValuePropertyClash()

Since only attributes named "value" can conflict with the special "value" 
property, the solution to Proposal 2 (SDO-71) will also solve this issue, 
as long as the special "value" property is treated like an element-type 
property. This will be the case, given the proposed wording for SDO-71, 
that is, it uses XSDHelper.isAttribute() as its test. Therefore, since the 

special "value" property is not an attribute, it will be treated like an 
element.



---------------------------------------------------------------------
To unsubscribe from this mail list, you must leave the OASIS TC that
generates this mail.  Follow this link to all your TCs in OASIS at:
https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php 




---------------------------------------------------------------------
To unsubscribe from this mail list, you must leave the OASIS TC that
generates this mail.  Follow this link to all your TCs in OASIS at:
https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php 

  

SDO3-XMLFidelityAndSdoPath.doc