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EReX: A Conceptual Model for XML

EReX: A Conceptual Model for XML. Murali Mani XSym, 2004 Aug 30, 2004. Motivations behind this work. Goal 1: Many different schema languages for XML: DTD, RELAX NG, W3C XML Schema Different structural specification characteristics (subclasses of regular tree grammars).

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EReX: A Conceptual Model for XML

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  1. EReX: A Conceptual Model for XML Murali Mani XSym, 2004 Aug 30, 2004

  2. Motivations behind this work • Goal 1: • Many different schema languages for XML: DTD, RELAX NG, W3C XML Schema • Different structural specification characteristics (subclasses of regular tree grammars). • Also different constraint specification characteristics. • Which XML schema language is good for database applications? • Goal 2: • An application wants to design an XML logical schema. What is the process? DSRG, WPI

  3. Deliverables • EReX (ER extended for XML) • A conceptual model for modeling any database application. • XML schema language characteristics needed for database applications. DSRG, WPI

  4. Binary 1:n relationships Binary m:n relationships ER Model DSRG, WPI

  5. N-ary relationships Recursive relationships ER Model DSRG, WPI

  6. Extensions to ER: Categories PersonCity, PersonZip are categories of Person Book, Paper are categories of Article • Note: • Article does not have a key attribute. • A is category of B  any instance of A is also instance of B DSRG, WPI

  7. PersonCity  PersonZip =  PersonCity  PersonZip = Person personBook  personPaper =  personBook  personPaper = Person confPaper  journalPaper =  confPaper  journalPaper = Paper Extensions to ER: Coverage Constraints DSRG, WPI

  8. Extensions to ER: Order constraints DSRG, WPI

  9. EReX: Summary • EReX = ER extended with categories, coverage constraints and order constraints. • Any database applications can be modeled in EReX. • Implications • Global Document order is not significant for our applications. • Rather, what is significant is order specified in the relationship. DSRG, WPI

  10. XGrammar • Structural specification using regular tree grammar. • Constraint specification on types (rather than path expressions). DSRG, WPI

  11. XGrammar Example Library  library (Person*) Person  person (@name, ((@city, @state) + @zip), (Book* + Paper*), Review*) Book  book (@btitle, @ISBN, @BID) Paper  paper (@ptitle, @year?, @PID) Review  review (@article, @rating) Constraints: key (Person) = <@name>; key (Book) = <@ISBN>; key (Paper) = <@ptitle>; key (Review) = <parent::person/@name, @article> article::IDREF REFERENCES (Book + Paper) DSRG, WPI

  12. EReX schema  XML schema – binary 1:n relationship types • Parent-child: • Professor  professor (@pname, @age, Student*) • Student  student (@sname, @year) • ID/IDREF • Professor  professor (@pname, @age, @PID) • Student  student (@sname, @year, @advisor) • advisor::IDREF REFERENCES (Professor) • Key/Foreign Key • Professor  professor (@pname, @age) • Student  student (@sname, @year, @advisor) • Student (advisor) REFERENCES Professor (@pname) DSRG, WPI

  13. EReX schema  XML Schema – binary m:n relationship types • Person  person (@name, @zip, Review*) • Review  review (@rating, @BookRef) • Book  book (@ISBN, @title, @year, @BID) • BookRef::IDREF REFERENCES (Book) DSRG, WPI

  14. EReX schema  XML Schema – ternary relationship types • Company  company (@name, Supply+) • Supply  supply (@ProductRef, @CityRef, @quantity) • Product  product (@name, @ProductID) • City  city (@name, @CityID) • ProductRef::IDREF REFERENCES (Product) • CityRef::IDREF REFERENCES (City) DSRG, WPI

  15. EReX schema  XML Schema – recursive relationship types • Part  part (@name, Part*, @qty?) DSRG, WPI

  16. PersonCity  PersonZip =  PersonCity  PersonZip = Person EReX schema  XML Schema – coverage constraints • Person  person (@name, (@city, @state) + @zip)) DSRG, WPI

  17. confPaper  journalPaper =  confPaper  journalPaper = Paper EReX schema  XML Schema – coverage constraints • Conference  conference (@name, @venue, Paper*) • Journal  journal (@name, @publisher, Paper*) • Paper  paper (@title) DSRG, WPI

  18. personBook  personPaper =  personBook  personPaper = Person EReX schema  XML Schema – coverage constraints • Person  person (@name, (Book+ + Paper+)) • Book  book (@isbn, @title) • Paper  paper (@title, @journal) DSRG, WPI

  19. EReX schema  XML Schema – order constraints • Order in the XML model • Person  person (@name, @address, Book*) • Using order attributes • Person  person (@name, @address, @PersonID) • Book  book (@isbn, @title, @PersonRef, @order) • PersonRef::IDREF REFERENCES (Person) DSRG, WPI

  20. EReX schema  XML Schema – Summary • Translation algorithm captures all entity types, relationship types. • It captures most cardinality constraints (some minimum cardinality constraints may be lost). • It captures all categories • It captures all order constraints. • It captures most coverage constraints (some coverage constraints may be lost). • Resulting XML Schema • Single type tree grammar. • Constraints specified on types. DSRG, WPI

  21. Acknowledgements: Antonio Badia, University of Louisville, Kentucky Dongwon Lee, PennState University Members of DSRG and colleagues at WPI DSRG, WPI

  22. Thank You URL: http://www.cs.wpi.edu/~mmani Email: mmani@cs.wpi.edu Questions? DSRG, WPI

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