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Hi Marc, <YourComment> Actually there is another representation of the information in the DTD that is present: the application that uses the document. Unfortunately the representation is in C++, Java or some other language. This introduces a synchronization problem between the two. The DOM api for instance gives you access to the parsed document tree, but a sizable amount of independent code must be written to essentially parse the DOM tree into the form the application needs. The result is the structure is in 2 different forms, declarative and procedural, which must be kept in sync. </YourComment> <Reply> You are right. but I can construct a DOM without any validation. The whole point here is: if I need validation at the receiving end why not use SGML which is more elaborate and necessarily need validation (because of the possibility to have omittags). If however, we do not need validation at the receiving end then, we are better to use XML that, because of its structure, can be parsed without validation and then a DOM could be created for procedural language consumption. But you are right to say that from the serialized format I have to construct a model (i.e. a structure) that interpreters can access. The DOM is the XML way to do it and the grove for the SGML way (DOM and grove concept are similar enough to reduce one to the other) to become useful XML life cycle could be expressed like: a) XML format creation: we need a DTD, so that the editor can validate the document or simply prevent me to create an invalid document. b) transport c) receiving end: interpretation. The interpreter needs a parser. A validating parser is not necesssary with XML, It seems that we have several kinds of parsers: 1- event driven 2- function call within a loop 3- DOM producer d) The interpreter knows the semantic and do something. In fact, XML rules do not convey semantics only syntax. Xpointers or Xlinks are domain specific languages that add a semantic layer to XML. XHTML also. In fact, all these concept where existing in the SGML world. Waht we gained with XML compared to SGML is simplier parsing rule. So simple that validation is no longer necessary to do a complete parsing operation. The SGML syntax is more tricky because you need to tell the parser that some markups are not with an end tag, thus, the need for a DTD which has the main function to tell the parser some parsing rules like where a tag begin and end. So, because of the "well formed" constraint we gained that now parser do not a DTD to accomplish their task, the rule is clear on how a markup begin and ends. My conclusion: we gained with XML the fact that a parser do not need to do validation. Otherwise its only changing the XML extension to a sgml document. So, to go from "mydocument.sgml" to "mydocument.xml" whitout really changing anything except some minor modifications in the DTD declaration. That may be good for marketing reasons but surely not for technical reasons. </Reply> Regards Didier PH Martin mailto:martind@n... http://www.netfolder.com 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/ and on CD-ROM/ISBN 981-02-3594-1 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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