Proposal: Section 4.13.2 - Generating XSDs

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

Hello All,

For section 4.13.2 we (Oracle) feel that XSDHelper should always return an XML schema generated off of the SDO metadata (as opposed to returning the original schema).  Our rationale is as follows:

• The user already has access to the original schema.
• Since the original schema already exists it is a waste of memory to store the XML schema only to return it later, since it may never be asked for.
  
• Our (Oracle) users use a lot of imported/included schemas which would make it difficult to return the original schemas.
• The XSDHelper generates schemas off of a list of types, what subset of types derived from the original define need to be passed to the generate to trigger the original schema to be returned.
• Since the generated schema may be incompatible with the original schema (as per the spec), the generated schema gives users realistic expectations of what there XML document will look like.
  

As promised in the last SDO call, here is my proposed wording on section 4.13.2.  Since the spec already stated that the original XSD should be returned, I don't feel this needs to be changed.  However the compliance point must not require this behaviour (although it may encourage it).  As concessions have been made in other areas to give implementations freedom to do what is best for their customers, I propose we do the same here.

Current Wording

4.13.2 Generating XSDs

The XSDHelper can generate a new XSD for Types that do not already have an XSD definition. This is useful when the source of the Types come from services in another domain, such as relational databases, programming languages and UML. The generated XSD format is described later in 8:  Generation of XSD from SDO Type and Property.

If an XML Schema was originally used to define the Types, that original XSD should be used instead of generating a new XSD. If a new XML Schema is generated when one already exists, the generated schema and the original schema will not be compatible and will validate different documents. The XMLHelper will follow the original XSD if one exists, otherwise it will follow a generated XSD.

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Proposed Wording

4.13.2 Generating XSDs

The XSDHelper can generate a new XSD for Types that do not already have an XSD definition. This is useful when the source of the Types come from services in another domain, such as relational databases, programming languages and UML. The generated XSD format is described later in 8:  Generation of XSD from SDO Type and Property.

If an XML Schema was originally used to define the Types, that original XSD should be used instead of generating a new XSD. If a new XML Schema is generated when one already exists, the generated schema may be more lax than the original schema.  In certain circumstances the XML schemas may not be compatible.

-Blaise