• To: Michael Kay <mike@s...>
• Subject: Re: schema-aware XML parser (java heap error)
• From: Bob Foster <bob@o...>
• Date: Fri, 03 Jun 2005 10:24:34 -0700
• Cc: xml-dev@l...
• In-reply-to: <200506021929.j52JTKW12504@r...>
• References: <200506021929.j52JTKW12504@r...>
• User-agent: Mozilla Thunderbird 1.0.2 (Windows/20050317)

Michael Kay wrote:
 > The standard algorithms for generating a finite-state machine from a 
grammar
 > suffer from the problem that the number of possible states becomes very
 > large when you use a large value of minOccurs or maxOccurs, which 
causes an
 > increasing use of memory. Saxon's schema processor deals with this by
 > treating a large maxOccurs as if you had specified "unbounded" (with a
 > warning), which is only marginally better than falling over completely.
 > Henry Thompson was promising to publish an improved algorithm but I 
haven't
 > seen it yet...
 >
 > I would suggest that you treat this constraint as one of those that 
are best
 > checked at application level, or using a tool such as schematron.
 > Grammar-based validators aren't good at this job.

This note may be of interest:

http://jroller.com/comments/bobfoster/FullSpeedAhead/derivatives_of_bounded_repitition

(sic)

Bob Foster

• References:
  • RE: schema-aware XML parser (java heap error)
    • From: "Michael Kay" <mike@s...>

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