[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: Caution using XML Schema backward- or forward-compatibilit
Thanks Bryan and David. I believe that we are all in agreement, but some clarification is needed to make that apparent: "My XML Schema is backward-compatible." That statement only tells us that the XML Schema can *validate* old instance documents. It tells us nothing about whether the semantics or relationships (e.g. co-constraints) are backward-compatible. Thus, XML Schema backward-compatibility tells us nothing about whether an application which is implemented to process instance documents conforming to the new XML Schema can *process* old instance documents. Accordingly, I am raising caution to the common fallacy: "If my XML Schema is backward-compatible then my application can process old instance documents." Do you agree? /Roger -----Original Message----- From: David Carver [mailto:d_a_carver@y...] Sent: Wednesday, December 26, 2007 3:06 PM To: bryan rasmussen Cc: Costello, Roger L.; xml-dev@l... Subject: Re: Caution using XML Schema backward- or forward-compatibility as a versioning strategy for data exchange bryan rasmussen wrote: > Well, I think changing the semantics of elements falls outside the > normal understanding of compatibility. > > I agree...if you change the meaning of an element, you have broken forward compatibility. Forward compatibility for any grammar has to take into account not only the data in the elements, but the semantic definition of what those elements mean.
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