Tired of complicated specifications You just RELAX

1
Tired of complicated specifications? You just
RELAX!

• MURATA Makoto (INSTAC XML SWGHIYAMA Masayuki
  (INSTAC XML SWG KOSAKI Motohiro (Matsushita AVC
  Multimedia Software)

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What is RELAX?

• RELAX (REgular LAnguage description for XML) is a
  specification for describing XML-based languages.
• RELAX is expected to become JIS technical
  reports.

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Comparison with DTD

• Description in RELAX is represented by tags and
  attributes.
• RELAX has rich datatypes.
• RELAX is namespace-aware.

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Standardization of RELAX

• INSTAC XML SWG of Japan standardizes RELAX.
• RELAX is expected to become JIS technical reports
  by June, 2000.
• RELAX is likely to be submitted to the fast track
  of ISO.

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RELAX Core and RELAX Namespace

• RELAX RELAX Core RELAX Namespace
• RELAX Core single namespace
• 2000 March
• RELAX Namespace multiple namespaces
• 2000 June

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Conformance levels of RELAX Core

• RELAX Core, classic DTD features - default
  values - entities - notations datatypes
• RELAX Core, fully relaxed RELAX Core, classic
  Horn clauses regular hedge grammars

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RELAX Core, classic

• ltmodulegt elements and ltinterfacegt elements
• Element type declarations
• Parameter entities for content models
• Attribute-list declarations
• Parameter entities for attribute declarations

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ltmodulegt and ltinterfacegt

• ltmodulegt ltinterfacegt ltexport labels "doc " /gt
  lt/interfacegt ...lt/modulegt

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Element type declarartions (1)

• lt!ELEMENT section (para)gt
• ltelementRule pred"section"gt ltref label"para"
  occurs""/gtlt/elementRulegt

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Element type declarartions (2)

• lt!ELEMENT para (PCDATA fnote)gt
• ltelementRule pred"para"gt ltmixedgt ltref
  label"fnote" occurs""/gt lt/mixedgtlt/elementR
  ulegt

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Parameter entities for content models

• lthedgeRule label "inline"gt ltchoicegt ltref
  label "a"/gt ltref label "special"/gt ltref
  label "phrase"/gt lt/choicegtlt/hedgeRulegt

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Attribute-List Declarations

• lt!ATTLIST section id ID REQUIREDgt
• lttag name"section"gt ltattribute
  name"id" type"ID" required"true"/gtlt/taggt

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Parameter entities for attribute declarations

• ltattList pred "common "gt ltattribute
  name"id" type"ID" required"true"/gtlt/attLis
  tgt
• lttag name "section" gt ltref pred
  "common"/gtlt/taggt

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Comparison with XML Schema

• Datatypes are borrowed from XML Schema Part 2.
• RELAX is much simpler than XML Schema Part 1.
• XML Schema will take long time. RELAX will be
  available very soon.
• XML Schema attaches semantics to documents, but
  RELAX does not.
• XML Schema requires extensions to DOM and SAX,
  but RELAX does not.

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Will RELAX survive?

• As of today, nobody knows.
• At best, standard bodies merely suggest
  specifications.
• Users and developers make the final call.
• RELAX may survive
• RELAX can be easily implemented
• Migration from DTD to RELAX and from RELAX to XML
  Schema are kept easy
• RELAX is not controlled by any private company.

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RELAX helps migration from DTD to XML Schema

• Use RELAX and datatypes right now.
• Migrate to XML Schema or DTD, when necessary and
  possible.
• If you use RELAX Core, classic,
• Conversion is automatic
• No loss of information

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RELAX Core, fully relaxed

• Regular Hedge Grammars
• Ancestor-sensitive content models
• Local scoping
• Equivalence classes
• Horn Clauses
• Mutually-exclusive attributes
• Attribute-sensitive content models

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Ancestor-sensitive content models

• ltelementRule pred"para" label"paraWithFNotes"gtlt
  mixedgt ltref label"footnote" occurs""/gtlt/mixed
  gt
• lt/elementRulegt
• ltelementRule pred"para" label"paraWithoutFNotes"
  gtltmixedgt ltempty/gtltmixed/gt
• lt/elementRulegt

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Ancestor-sensitive content models, continued

• ltelementRule pred "sec"gtltref label"paraWithFNot
  es" occurs""/gt
• lt/elementRulegt
• ltelementRule pred "table-cell"gtltref
  label"paraWithoutFNotes" occurs""/gt
• lt/elementRulegt

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Simulating local scoping

• ltelementRule pred"point"gt ltelement name"x"
  type"integer"/gt ltelement name"y"
  type"integer"/gtlt/elementRulegt

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Simulating equivalence classes

• blockElement
• ol
• ul
• lthedgeRule label"blockElement"gt ltref
  label"ol"/gtlt/hedgeRule gtlthedgeRule
  label"blockElement"gt ltref label"ul"/gtlt/hedgeRu
  le gt

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Mutually exclusive attributes

• lttag name"A"gt ltattribute name"name"
  type"NMTOKEN"/gt ltattribute name"href"
  type"none"/gtlt/taggtlttag name"A"gt ltattribute
  name"href" type"URI"/gt ltattribute name"name"
  type"none"/gtlt/taggt

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Attribute-sensitive content models

• lttag name"div" pred"div-as-section"gtltattribute
  name"class" type"NMTOKEN" required"true"gt ltenu
  meration value"section /gtlt/attributegt
• lt/taggt
• lttag name"div" pred"div-as-subsection"gt
  ltattribute name"class" type"NMTOKEN"
  required"true"gt ltenumeration value"subsection
  /gtlt/attributegt
• lt/taggt

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Attribute-sensitive content models, continued

• ltelementRule pred"div-as-section"gt
• ltref label"div-as-subsection" occurs""/gt
• lt/elementRulegt

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Implementations

• DTD-to-RELAX (in Java)
• Alpha version is already available
• Verifier of RELAX Core (in C)
• Alpha version is already available
• Generation of Java classes from RELAX Core
• Alpha version is already available

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Official site for RELAX

• http//www.xml.gr.jp/relax/
• FAQ
• Tutorial (HOW TO RELAX)
• Implementations
• Specifications (in preparation)

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Conclusion

• RELAX will be available very soon.
• Enjoy and RELAX!