[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Parser question... (DTD pre-parsng)
Kim Covil <kimc@n...> wrote > >...I have been wondering whether there are any >tools out there that will 'cache' the parsing of a DTD... As all >our resources use the same DTD, each time a view is created the >xml file is parsed... the DTD is referenced... the DTD is parsed >and then the xml is validated... > A very interesting question. I had the same thought about a related problem: the cost of repeated parsing and validation of the same XML document instance. I did a few experiments to try and devise a format for "pre-parsed XML" that would be faster to read than the original. My experiments failed, mainly I think because most of the formats I tried used a greater number of bytes than the original, and the parsing cost is dominated by the "read next byte" cost. For reference, the three formats I played with were: - a file representing a sequence of SAX events - a Java serialisation of this sequence - a variant of James Clark's "canonical XML" (with tricks such as minimized end tags) I came to the conclusion that the last of these could give a slight saving but the gain isn't worth the pain. The only practical way I found of cutting out repeated work was to remove the DTD reference once I know the document is valid. With very few exceptions (e.g. white space handling, attribute defaults) the presence of a DTD makes no difference to the processing of a valid document, other than to add to its cost. And if these features (white space, default attributes) are important, you can apply them to the instance in a preprocessing stage. Mike Kay xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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