Re: [xml-dev] RE: Caution using XML Schema backward- or forward-compatib

[David Carver <d_a_carver@yahoo.com>]

Costello, Roger L. wrote:
> I would like to propose the following data versioning principle:
>  
> PRINCIPLE OF WEB SERVICE DATA VERSIONING
> Don't base your web service data versioning strategy on a data 
> validation strategy. Rather, base it on business needs.
>  
> DISCUSSION
> Don't base your versioning strategy on an XML validation strategy, 
> such as maintaining backward compatible XML Schemas. It's the data 
> that the web service makes available to its consumers that matters, 
> not how the schema is designed. Your web service may have a business 
> need to create a new version in which new elements are added, old 
> elements are deleted, and existing elements are rearranged ... many of 
> these changes would not be possible if your versioning strategy were 
> constrained by some XML validation strategy such as trying to maintain 
> backward compatible XML Schemas. The only thing that matters is the 
> XML instance documents that the web service makes available to its 
> consumers. The design of the XML Schema that the instance documents 
> conform to is irrelevant.
>  
> QUESTIONS
>  
> 1. Do you agree with this principle?
> 2. If so, can you provide a name for the principle?  (e.g., the 
> _______ principle)
>  
> /Roger
>  
Yes this works, as long as you are talking about the XML Instance and 
not the applications that process it that may have been doing data 
binding against the schemas.   If you are just talking the data that is 
transmitted over the wire.