SUMMARY: XML Validation Issues (was: several threads)
It seems useful to summarize some of the many issues generated directly or indirectly by my original post, "Why Doesn't IE5 use the DTD to Validate?" and the spin-off threads "XML is broken" (XSL list), "Between raw and cooked II: Are? DTDs are just for validation" (sic; xml-dev), and "Is validity an option?" (xml-dev). - What precisely is a validating parser obligated to do? What type of parsing behavior can XML authors _always_ expect from a "validating parser"? - What aspects of XML processing are optional for a validating parser? - There is a major distinction between reading a DTD and validating, as James Clark states: "Reading the DTD and validating aren't the same thing. Unless a document has standalone="yes", the browser should always read a provided DTD so that it can correctly - default attributes - normalize attribute values - expand entity references None of these things involve validation." - What specific aspect of a DTD (e.g., the inclusion of ELEMENTS, not just entities) should signal to the parser that it must report validation errors to the client? - Under what situations is a parser allowed to ignore external entities, the external DTD subset, and by extension, entity and attribute declarations in the external DTD subset? - When is well-formedness sufficient and validation overkill? - Should a web browser with an XML parser require the document author to enable validation via scripting, should validation be the default, or should the end user be able to toggle validation (and if so, how)? - What is the desired behavior of a validating parser in different client situations (browsing vs. EDI vs. databases, etc.)? - Is there a need for a term to describe a parser that falls between non-validating and validating? (Something that decries the behavior common to AElfred, IBM's xml4j, Sun's Project X parser and Microsoft's parser.) - Should the XML spec be changed to ensure that both non-validating and validating parsers produce the same parse tree, such as by specifying that external entities and default attributes etc. be expanded? - What does the XML spec say specifically about these issues? Where is the spec lacking in terms of specificity? Conformance section ref: http://www.w3.org/TR/REC-xml#sec-conformance - Should the XML Schemas Working Group address some of the holes in the XML spec, especially in terms of conformance? Should it be the job of the Infoset WG? SAX2? Anyone want to add to this list? More importantly, anyone want to take a crack summarizing what they believe to be the majority and/or minority views? - Ken Sall ksall@xxxxxxx, kensall@xxxxxxxx - Century Computing Division http://www.cen.com/ - AppNet, Inc. http://www.appnet.net/ - NG-HTML: Next Generation HTML http://www.cen.com/ng-html/ - XML at Web Developers Virtual Lib http://WDVL.com/Authoring/Languages/XML/ - MW3: Motif on the World Wide Web http://www.cen.com/mw3/ XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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