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RE: [xml-dev] The limitations of XPath and navigation for XML database processing

I think the point is, the steps specified by the path do not have to be the steps followed by XPath to arrive at the node. So you can’t say that XPath exposes the internal logic externally since the steps may not be the internal logic it uses at all, and it’s fair to say that one interpretation of the path from users can’t be used to determine whether the language is procedural or declarative.

 

However, if you are saying that given a requirement to address the very node C that appears in a certain context such as /A/B/C, there is an alternative to specify the requested C that is better than the way to specify the steps navigating to the C, then I would suggest you might argue more about it rather than declaring that XPath as a programming language is procedural.  

 

 

Lisa

 

 


From: mike@adatinc.com [mailto:mike@adatinc.com]
Sent: Thursday, February 07, 2008 6:38 PM
To: Xia Li; mike@adatinc.com; noah_mendelsohn@us.ibm.com
Cc: xml-dev@lists.xml.org
Subject: Re: [xml-dev] The limitations of XPath and navigation for XML database processing

 

 

-----Original Message-----
From: Xia Li [mailto:xli@galdosinc.com]
Sent: Thursday, February 7, 2008 08:14 PM
To: mike@adatinc.com, noah_mendelsohn@us.ibm.com
Cc: xml-dev@lists.xml.org
Subject: RE: [xml-dev] The limitations of XPath and navigation for XML database processing

Hi Mike,

 

You wrote, ?What it boils down to with me is that XPath is logically specifying the logic (externally) that is needed to be performed (internally). The external navigation instructions must be specified procedurally to correctly define any of the possible choices for internal operations.?

  

But it is not XPath requires you to define the detailed step from A to C with /A/B/C. It is the requirement of your application that requires you to give such a detailed step so that you can get the C that appears within B which is under A. If your application, for example, just want to retrieve C no matter where it appears, then even with XPath, you can just say ?//C? without giving every step from A to C. So I think the path is actually says what you want instead of instructing the processor how to get it.  

  

Lisa

  


Hi Lisa,

 

What about ?//C//G?.  To me as an external user, it says go to C, then go to G (from C). How it is processed internally is not important as long as it gets the right result.  "//C" could be argued either way I think, but generally navigation has to be externally specified as a series of steps.

 

            /Mike

 



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