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Re: RE: Are people really using Identity constraintsspecified

• To: xml-dev@l...
• Subject: Re: RE: Are people really using Identity constraintsspecified in XML schema?
• From: costello@m...
• Date: Wed, 18 Aug 2004 19:19:10 -0400
• Priority: normal

Hi Folks,

I remember reading a long time ago a posting by David Megginson.  Paraphrasing, David said, "when dealing with XML you are working down at the bare metal".  

Other technologies work down at the bare metal, such as TCP/IP.  Perhaps there are lessons to be learned there?  Certain TCP/IP packets are rejected as bad and the other packets are accepted and passed up to other layers, where those layers perform additional constraint checking.

If we accept the conjecture that XML is down at the bare metal level, then perhaps the only constraint checking that should be done by an XML Schema is parallel to the kinds of checking that is done on TCP/IP packets.  All other constraint checking is passed up to other layers.

Can someone characterize the kind of constraint checking that is done on TCP/IP packets?  What would be the parallel constraint checking in XML Schemas?  /Roger

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