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Subject: AW: [sdo] ISSUE 66: Proposed Resolution, One More Attempt


Hi Frank,

I'd be OK with this wording, assuming we also agree to revisit later, and try to loosen up the definition of compatibility.

Can I ask for a "straw poll", to see where we are with getting acceptance on this issue.  If you have objections, or suggestions for modifications, please state them.

Ron
 
-----Ursprüngliche Nachricht-----
Von: Frank Budinsky [mailto:frankb@ca.ibm.com] 
Gesendet: Mittwoch, 2. April 2008 17:01
An: sdo@lists.oasis-open.org
Betreff: [sdo] ISSUE 66: Proposed Resolution, One More Attempt

Hi Ron,

Here's one more attempt, that hopefully addresses your concerns.

Frank.

4.5.4    Compatibility Between Types
Types in different HelperContexts may represent the same underlying 
business data.  Often Types in different contexts are closely enough 
related that it is possible to transfer the business data between the 
contexts using the DataHelper.project() method.  Types that are closely 
enough related to allow this are termed compatible Types. 

Two DataTypes are compatible if they have the same instance class.

Two DataObject (Complex) types, T1 and T2, are considered compatible if 
their definitions are identical or differ only in the following ways:

1.      T1.instanceClass != T2.instanceClass
2.      T1.name != T2.name or T1.aliasNames != T2.aliasNames, provided 
there is a matching name in the two sets of names 
3.      Corresponding properties P1.name != P2.name or P1.aliasNames != 
P2.aliasNames, provided there is a matching name in the two sets of names
4.      Corresponding properties P1.containment != P2.containment

The properties in T1 and T2 need not be in the exact same order, as long 
as corresponding properties can be uniquely matched in the two types 
according to the above rules.

Implementations may choose to loosen these requirements on compatibility, 
for instance, an implementation may choose to allow the set of properties 
in T1 to be a subset of the properties in T2.  An implementation 
definition of compatibility may not be made more restrictive.





Frank Budinsky/Toronto/IBM
04/02/2008 10:10 AM

To
sdo@lists.oasis-open.org
cc

Subject
Re: AW: [sdo] ISSUE 66:  Proposed Resolution, Second Attempt





Oops, right after hitting the "send" buttom, I noticed your point about 
DataTypes name mismatch. Good point. How about this:

4.5.4    Compatibility Between Types
Types in different HelperContexts may represent the same underlying 
business data.  Often Types in different contexts are closely enough 
related that it is possible to transfer the business data between the 
contexts using the DataHelper.project() method.  Types that are closely 
enough related to allow this are termed compatible Types. 

Two DataTypes are compatible if they have the same instance class.

Two DataObject (Complex) types, T1 and T2, are considered compatible if 
their definitions are identical or differ only in the following ways:

1.      T1.instanceClass != T2.instanceClass
2.      T1.name != T2.name or T1.aliasNames != T2.aliasNames, provided 
there is a matching name in the two sets of names 
3.      Corresponding properties P1.name != P2.name or P1.aliasNames != 
P2.aliasNames, provided there is a matching name in the two sets of names
4.      Corresponding properties P1.containment != P2.containment

Implementations may choose to loosen these requirements on compatibility, 
for instance, an implementation may choose to allow the set of properties 
in T1 to be a subset of the properties in T2.  An implementation 
definition of compatibility may not be made more restrictive.

Frank.





Frank Budinsky/Toronto/IBM@IBMCA 
04/02/2008 09:55 AM

To
sdo@lists.oasis-open.org
cc

Subject
Re: AW: [sdo] ISSUE 66:  Proposed Resolution, Second Attempt






Hi Ron,

> I think we need to define what "corresponding properties" (in point 
> 3) means.

Personally, I think it's clear because of the statement:

    "definitions are identical or differ only in the following ways:"

Since we're talking about the delta from identical, corresponding 
properties in this case means "otherwise identical". 

Do others think this is unclear?

> I also think we need to say something about data types.

Since none of the points in the list apply to DataTypes, other than #2, 
DataTypes need to be identical (except for name/aliasName). I think that's 

what we want.

> However, I would also suggest saying 
> something about OpenContent properties associated with the type (or 
> property) not being relevant

I'm OK with adding that, but think it may be better to cover it with "
Implementations may choose to loosen these requirements" for now, and 
maybe add something later, when it's clear exactly what we want to 
require.

Frank.

"Barack, Ron" <ron.barack@sap.com> wrote on 04/02/2008 03:58:10 AM:

> Hi Frank,
> 
> I think we need to define what "corresponding properties" (in point 
> 3) means.  I believe you mean that P1 and P2 "correspond" to each 
> other if the is a match between the names.  I'm not sure how to 
> phrase this formally, though (everytime I try I wind up talking 
> about the intersection of sets).
> 
> I also think we need to say something about data types.  I like the 
> definition of datatypes matching iff their instance class matches. 
> This allows something that's defined through java to hava a property
> of type "String" be compatible to something defined in schema, that 
> has a property of type "URI".
> 
> Seeing that we allow the definition to be loosed, then I guess I can
> live with this proposal.  However, I would also suggest saying 
> something about OpenContent properties associated with the type (or 
> property) not being relevant (at least, OpenContent properties other
> than those mentioned in the spec).  Here's the use-case I'm thinking
> about.  Imagine an RDB DAS that keeps the table name associated with
> a type in an open content property.  I would hope that the users of 
> this DAS would have type systems that need not (indeed, should not) 
> know about this OR mapping information.  The two types (on the 
> client and on the DAS) should be compatible.
> 
> 
> Best Regards,
> Ron
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Frank Budinsky [mailto:frankb@ca.ibm.com] 
> Gesendet: Dienstag, 1. April 2008 23:49
> An: sdo@lists.oasis-open.org
> Betreff: Re: [sdo] ISSUE 66: Proposed Resolution, Second Attempt
> 
> Hi Ron,
> 
> Here is my suggested wording for the compatibility section. If we don't 
> all agree on containment, then we can remove item 4 for now.
> 
> Frank.
> 
> 4.5.4    Compatibility Between Types
> Types in different HelperContexts may represent the same underlying 
> business data.  Often Types in different contexts are closely enough 
> related that it is possible to transfer the business data between the 
> contexts using the DataHelper.project() method.  Types that are closely 
> enough related to allow this are termed compatible Types. 
> 
> Two types, T1 and T2, are considered compatible if their definitions are 


> identical or differ only in the following ways:
> 
> 1.      T1.instanceClass != T2.instanceClass provided T1 and T2 are not 
> DataTypes
> 2.      T1.name != T2.name or T1.aliasNames != T2.aliasNames, provided 
> there is a matching name in the two sets of names 
> 3.      Corresponding properties P1.name != P2.name or P1.aliasNames != 
> P2.aliasNames, provided there is a matching name in the two sets of 
names
> 4.      Corresponding properties P1.containment != P2.containment
> 
> Implementations may choose to loosen these requirements on 
compatibility, 
> for instance, an implementation may choose to allow the set of 
properties 
> in T1 to be a subset of the properties in T2.  An implementation 
> definition of compatibility may not be made more restrictive.
> 
> 
> 
> 
> 
> "Barack, Ron" <ron.barack@sap.com> 
> 04/01/2008 01:40 PM
> 
> To
> <sdo@lists.oasis-open.org>
> cc
> 
> Subject
> [sdo] ISSUE 66:  Proposed Resolution, Second Attempt
> 
> 
> 
> 
> 
> 
> Hi Everyone,
> 
> I've tightened up the definition of compatibility. Although it doesn't 
go 
> so far as to say "exactly the same except...", I think most of the 
problem 
> cases are avoided, while still support our SCA wiring use-cases. I'd be 
> pretty sorry to make supporting compatibility between types that have 
> different containment structures a vendor extension: it's just too 
> important to our JPA/DAS -> BPEL use case.
> 
> If this wording is not acceptable, let's try to do a couple of 
iterations 
> over the mailing list.
> 
> Best Regards,
> Ron
> 
> 4.5.2    Type Contents
> A Type will always have:
> Name - A String that must be unique among the Types that belong to the 
> same URI in the same HelperContext.
> URI - The logical URI of a package or a target namespace, depending upon 


> your perspective.
> Boolean fields indicating if the type is open, abstract, sequenced, or a 


> data type.
> 
> A Type can have:
> Properties - a list of Property objects defined by this Type. Types 
> corresponding to simple data types define no properties.
> Instance Class - the java.lang.Class used to implement the SDO Type.
> If DataType is true then a Type must have an Instance Class. Example 
> classes are: java.lang.Integer and java.lang.String. 
> If DataType is false, and generated code is used, then an Instance Class 


> is optional. Examples classes might be: PurchaseOrder and Customer. 
> ˇ       Aliases - Strings containing additional names. Alias Names must 
be 
> unique within a URI. All methods that operate on a Type by name also 
> accept alias names. For example, a Type might be assigned an alias name 
> for the domains it is used in: an XML Schema name "PurchaseOrderType", a 


> Java name "PurchaseOrder" and a database table name "PRCHORDR". 
> ˇ       Instance properties ? open content metadata extensions attached 
to 
> the Type instance.
> 
> 4.5.3    Name Uniqueness
> Within a single HelperContext, the combination of a URI and a Type names 


> or Type alias names uniquely identifies the type. Other HelperContexts 
may 
> have different (and conflicting) definitions for types having the same 
URI 
> and name.
> Property names and Property alias names are all unique within a Type and 


> any base Types. 
> 4.5.4    Compatibility Between Types
> Types in different HelperContexts may represent the same underlying 
> business data.  Often Types in different contexts are closely enough 
> related that it is possible to transfer the business data between the 
> contexts using the DataHelper.project() method.  Types that are closely 
> enough related to allow this are termed compatible Types. 
> The following rules are used to determine compatibility.
> 1.      Two DataTypes are compatible if they have the same instance 
class.
> 2.      A complex type T1 is compliant with a type T2.  The types are 
> compliant if 
> a)     The URI and name of both types are equal.
> b)     Both types are concrete.
> c)     T1.isSequenced() is identical to T2.isSequenced()
> d)     T1.isOpen() is identical to T2.isOpen()
> e)     T1.isNullable() is identical to T2.isNullable()
> f)       For every property P1 in T1 there is a property P2 in T2 such 
> that
>                                                     i.     P1.getName() 
is 
> equal to P2.getName()
>                                                    ii.     P1.getType() 
is 
> compatible with P2.getType()
>                                                   iii.     P1.isMany() 
is 
> identical to P2.isMany()
>                                                   iv. 
> XMLHelper.isXmlElement(P1) is identical to XMLHelper.isXmlElement(P2)
> g)     For every property P2 in T2, there is a property P1 in T1 such 
that
>                                                     i.     P1.getName() 
is 
> equal to P2.getName()
>                                                    ii.     P1.getType() 
is 
> compatible with P2.getType()
>                                                   iii.     P1.isMany() 
is 
> identical to P2.isMany()
>                                                   iv. 
> XMLHelper.isXmlElement(P1) is identical to XMLHelper.isXmlElement(P2)
> 
>  Implementations may choose to loosen these requirements on 
compatibility, 
> for instance, an implementation may choose to allow the set of 
properties 
> in T1 to be a subset of the properties in T2, that is, to require either 


> 2.f or 2.g.  An implementation definition of compatibility may not be 
made 
> more restrictive.  In particular, the following characteristics may not 
be 
> used in determining if types are compatible 
> 1.      The instance class (that is, the static SDO) associated with a 
> complex type.
> 2.      Whether the value of P1.isContainment() is identical to the 
value 
> of P2.getContainment()
> 3.      The XML or Java names of the properties.
> 4.      Any validation information (e.g., XSD facets) associated with a 
> DataType
> 5.      The order of the properties in Type.getProperties()
> 6.      The base types associated with either of the types.
> 7.      Whether or not properties are defined as bi-directional.
> 
________________________________________________________________________________
> 4.14.2          The Project method
> The DataHelper.project() method is used to move data between contexts. 
The 
> behavior of this method is as follows.
> Consider object O1, where O1.getType() is T1 and where 
> T1.getHelperContext() is C1.  Consider a context C2 that defines a Type, 


> T2, that is compatible to T1 according to the definition in section 
4.5.4. 
>  The method
>      DataObject O2 = C2.getDataHelper().project(O1);
> returns a DataObject O2 such that 
> 1.      O2.getType() is T2
> 2.      If P1.getType().isDataType() is true then O1.get(P1)==O2.get(P2)
> 3.      If P1.getType().isDataType() is false, then if O1.get(P1) is 
null, 
> O2.get(P2) is null, otherwise
>     O2.get(P2)==C2.project(O1.get(P1))
> If O1 and O2 are both sequenced, then the order of the elements in the 
> sequences will match.
> If C2 does not define a type that is compatible to T1 according to the 
> definition in section 4.5.4, the project operation MUST throw an 
> exception.
> The project operation leaves the DataObject O1, and all objects in the 
> transitive closure reachable from O1  in an undefined state.  O1 may be 
> returned to a defined state by reversing the project operation, i.e., 
>      C1.getDataHelper().project(O2);
> Notice that each DataObject has a single representation in each context, 


> That is,
>      DataObject O2 = C2.getDataHelper().project(O1);
>      DataObject O3 = C2.getDataHelper().project(O1);
>      assertSame(O2, O3);
>      DataObject O4 = C1.getDataHelper().project(O2);
>      assertSame(O1, O4); 
> 
> The project method must assure that the object returned from a 
projection 
> is valid according to the rules defined in the context where the 
object?s 
> type is defined.  This includes restrictions derived from the type?s 
> containment structure, e.g., there can be no objects in the containment 
> graph reachable from the projected object that have more than one 
> container.  For instance, consider an object P1, with Type T1, in 
context 
> C1.  Assume that it has 2 properties, ?a? and ?b?, neither of which are 
> marked as being a containment property.  Then it could be legal to set 
the 
> value of these properties to the same object, N1.   Now consider a 
second 
> type, T2, in context C2, that is compatible with T1 but in which the 
> properties ?a? and ?b? are both marked as being containment properties. 
> Then the DataObject P1 cannot be projected into the context C2, because 
> the object N1 would project to an object that has conflicting 
containment 
> properties.
> Similarly, an implementation must check than any bi-directional 
properties 
> have consistent values.  Of course, this is automatic if the properties 
> are bi-directional in both HelperContexts.  In the case where the 
original 
> object does not have a bi-directional property, an implementation must 
> check the consistency of both side of the property. 
> If the project operation would result in a datagraph that violates the 
> restrictions imposed by the type definitions in that context, the 
project 
> method MUST throw an exception.
> 
> 
> 
> 
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