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Re: Schema Evolution

• To: xml-dev@l...
• Subject: Re: Schema Evolution
• From: Ronald Bourret <rpbourret@r...>
• Date: Tue, 26 Oct 2004 19:56:51 -0700
• In-reply-to: <417EF9E9.1030103@u...>
• References: <EAAD28446720174391E26A9A505854560C06B8@M...> <417EF9E9.1030103@u...>
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Agreed.

This is at the top of the frequently asked questions I get about XML. 
The fact that nobody has come up with a simple and elegant solution 
leads me to believe that there isn't one, as does the fact that nobody 
has solved this in non-XML fields (database schemas, APIs, operating 
systems, etc.) either.

-- Ron

Ian Graham wrote:
> My own experience, on a large enterprise Web services project, is that 
> elegant schema / WSDL evolution is not possible. There is simply no way 
> to constrain the schema changes such that all existing applications are 
> guaranteed to work with the new versions. So we will create new services 
> (and keep the old) if anything needs to change.  We hope that governance 
> will help limit/control this revving process.
> 
> The situation is likely similar for other environments -- if you want to 
> guarantee that all previous apps dependent on the schema work, then you 
> can't change it.
> 
> If you think a schema change is idiot proof, you likely just haven't 
> found a suitably qualified idiot :-(

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