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Re: Push and Pull?

• To: xml-dev@l...
• Subject: Re: Push and Pull?
• From: "Clark C . Evans" <cce@c...>
• Date: Fri, 25 Jan 2002 12:59:18 -0500
• In-reply-to: <20020125123137.B16272@d...>; from cce@c... on Fri, Jan 25, 2002 at 12:31:37PM -0500
• References: <15977008ABB8D5118B1300805FA7A8F1815A99@c...> <005801c175e9$81e98880$0500a8c0@carnage> <20020125123137.B16272@d...>
• User-agent: Mutt/1.2.5i

If you buy the Random vs Sequential (Access Model)
distinction, you could "fix" DOM to provide both
Random and Sequential access via three modifications:

a) Give each node an "access" property.  This property
   can have one of three values:

   RANDOM       The node's content can be viewed as
                many times as desired.

   SEQUENTIAL   The node's content can only be viewed
                once.

   NOACCESS     The node's content has already been viewed.


b) Allow content accessors to throw a new "NoAccess"
   exception.  These accessors may only throw this exception
   if the access property of the node is NOACCESS.

c) When a content accessor is invoked, the node's access
   may change from SEQUENTIAL to RANDOM or NOACCESS.
   A node that has RANDOM access must forever stay with
   RANDOM access. 

Best,

Clark


On Fri, Jan 25, 2002 at 12:31:37PM -0500, Clark C . Evans wrote:
| On Sun, Nov 25, 2001 at 11:43:49AM -0800, Dare Obasanjo wrote:
| | No. The pull model has *nothing* to do with an in-memory 
| | representation of the document.
| 
| Yes.  Random vs. sequential access is an othogonal issue.
| 
| 
|          Sequential      Random
|        +----------------------------------------------------------
|        |
|   Push | SAX             (recursive visitor)
|        |
|   Pull | Pull Parser     DOM
|        |
|        +-------------------------------------------------------
| 
| The confusion arises since SAX and DOM are different
| in two regards: (a) processing model (push vs pull)
| and (b) access model (random vs sequential).  
| 
| The XML Pull Parser is an example which is SAX-like 
| in that it is sequential access, but DOM-like in that
| it has a pull interface.   The other permutation
| is a recurisive visitor interface.  You can scan
| the SML-DEV archives if you'd like more information
| on this... it doesn't seem to be as useful as the
| other three permutations.
| 
| Best,
| 
| Clark
| 
| -- 
| Clark C. Evans                   Axista, Inc.
| http://www.axista.com            800.926.5525
| XCOLLA Collaborative Project Management Software
| 
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-- 
Clark C. Evans                   Axista, Inc.
http://www.axista.com            800.926.5525
XCOLLA Collaborative Project Management Software

• References:
  • RE: Push and Pull?
    • From: "Sterin, Ilya" <Isterin@c...>
  • Re: Push and Pull?
    • From: "Dare Obasanjo" <kpako@y...>
  • Re: Push and Pull?
    • From: "Clark C . Evans" <cce@c...>

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