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Conceptual XML for Systems Analysis
Reema Al-KamhaPhD Dissertation Defense
Supported by NSF
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Motivation
SinceXML is now a standard for data representation
There is a need for A simple conceptual model for XML Tools to
Develop schemas for XML data storage Reverse-engineer XML storage structures to a conceptual
model for further development
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Dissertation Contributions Conceptual-XML (C-XML) Transformations
C-XML to XML Schema (to develop schemas for XML data storage)
XML Schema to C-XML (to reverse-engineer XML storage structures to a conceptual model for further development)
Observations and recommendations
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C-XML
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Conceptual XML (C-XML) C-XML has good conceptual-modeling characteristics Satisfies conceptual modeling requirements [Nec06,
SW06,Wild05] Graphical notation Formal foundation Structural independence Reflection of the mental model n-ary relationship sets Cardinality for all participants Ordering Allowance for irregular and heterogeneous structure …
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Transforming C-XML to XML Schema
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<?xml version="1.0" encoding="UTF-8"?><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"> <xs:element name="Root"> <xs:complexType> <xs:all> <xs:element ref="Students"/> <xs:element ref="Courses"/> <xs:element ref="GradStudents"/> <xs:element ref="UndergradStudents"/> </xs:all> </xs:complexType> <xs:keyref name="UndergradStudentOID-Keyref" refer="StudentOID-Key"> <xs:selector xpath="./UndergradStudents/UndergradStudent"/> <xs:field xpath="@UndergradStudentOID"/> </xs:keyref> <xs:keyref name="GradStudentOID-Keyref" refer="StudentOID-Key"> <xs:selector xpath="./GradStudents/GradStudent"/> <xs:field xpath="@GradStudentOID"/> </xs:keyref> </xs:element> <xs:element name="Students"> <xs:complexType> <xs:sequence> <xs:element name="Student" maxOccurs="unbounded"> <xs:complexType> <xs:sequence> <xs:choice minOccurs="1" maxOccurs="1"> <xs:element name="StudentName" type="xs:string"/> <xs:sequence> <xs:element name="FirstName" type="xs:string"/> <xs:element name="MiddleNames"> <xs:complexType> <xs:sequence> <xs:element name="MiddleName" minOccurs="0" maxOccurs="2"> <xs:complexType> <xs:attribute name="MiddleName" type="xs:string" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="MiddleName-Key"> <xs:selector xpath="./MiddleName"/> <xs:field xpath="@MiddleName"/> </xs:key> </xs:element> <xs:element name="LastName" type="xs:string"/> </xs:sequence> </xs:choice> <xs:element name="Semester-Course-Grades"> <xs:complexType> <xs:sequence> <xs:element name="Semester-Course-Grade" minOccurs="0" maxOccurs="unbounded"> <xs:complexType> <xs:attribute name="Semester" use="required"/> <xs:attribute ref="Course" use="required"/> <!-- C-XML: forall x (Course(x)=>exists [0:*] <x1, x2, x3> (Course(x) Student(x1) Semester(x2) Grade(x3) )) --> <xs:attribute name="Grade" type="xs:string" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="Semester-Course-Grade-Key"> <xs:selector xpath="./Semester-Course-Grade"/> <xs:field xpath="@Semester"/> <xs:field xpath="@Course"/> <xs:field xpath="@Grade"/> </xs:key> </xs:element> </xs:sequence> <xs:attribute name="StudentOID" type="xs:string" use="required"/> <xs:attribute name="StudentID" type="xs:string" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="StudentOID-Key"> <xs:selector xpath="./Student"/> <xs:field xpath="@StudentOID"/> </xs:key> <xs:key name="StudentID-Key"> <xs:selector xpath="./Student"/> <xs:field xpath="@StudentID"/> </xs:key> </xs:element> <xs:element name="Courses"> <xs:complexType> <xs:sequence> <xs:element name="Course" maxOccurs="unbounded"> <xs:complexType> <xs:attribute ref="Course" use="required"/> <xs:attribute name="Department" type="xs:string" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="Course-Key"> <xs:selector xpath="./Course"/> <xs:field xpath="@Course"/> </xs:key> </xs:element> <xs:element name="GradStudents"> <xs:complexType> <xs:sequence> <xs:element name="GradStudent" maxOccurs="unbounded"> <xs:complexType> <xs:attribute name="GradStudentOID" type="xs:string" use="required"/> <xs:attribute name="Advisor" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="GradStudentOID-Key"> <xs:selector xpath="./GradStudent"/> <xs:field xpath="@GradStudentOID"/> </xs:key> </xs:element> <xs:element name="UndergradStudents"> <xs:complexType> <xs:sequence> <xs:element name="UndergradStudent" maxOccurs="unbounded"> <xs:complexType> <xs:attribute name="UndergradStudentOID" type="xs:string" use="required"/> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="UndergradStudentOID-Key"> <xs:selector xpath="./UndergradStudent"/> <xs:field xpath="@UndergradStudentOID"/> </xs:key> </xs:element> <xs:attribute name="Course" type="xs:string"/></xs:schema>
C-XML XML Schema
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Algorithm Overview Generate a forest of scheme trees Translate an individual object set Translate an individual node Create a root node Add global uniqueness constraints Translate generalization/specialization hierarchies
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(Student, StudentID, StudentName, FirstName, LastName, (MiddleName)*, (Course, Semester, Grade)*)*
Generate Scheme Trees
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(Course, Department)*
Generate Scheme Trees
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(GradStudent, Advisor)*(UndergradStudent)*
Generate Scheme Trees
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(Student, StudentID, StudentName, FirstName, LastName, (MiddleName)*, (Course, Semester, Grade)*)*
(Course, Department)*
(GradStudent, Advisor)* (UndergradStudent)*
Generate Scheme Trees
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Student, StudentID, StudentName, FirstName, LastName
MiddleName Course, Semester, Grade
Course, Department GradStudent, Advisor UndergradStudent
(Student, StudentID, StudentName, FirstName, LastName, (MiddleName)*, (Course, Semester, Grade)*)*
(Course, Department)*
(GradStudent, Advisor)* (UndergradStudent)*
Generate Scheme Trees
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Individual Object Sets
<xs:attribute name="Department" type="xs:string"/><xs:attribute name="Course" type="xs:string"/><xs:attribute ref="Course"/><xs:element name="FirstName" type="xs:string"/><xs:element name="Student"> <xs:complexType> ... <xs:attribute name="StudentOID" type="xs:string" use="required"/> </xs:complexType></xs:element>
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Nodes
Students
Courses GradStudents UndergradStudents
MiddleNames
Course-Semester-GradesMiddleNames
Students
Student
MiddleName
Course GradStudent UndergradStudent
Course-Semester-Grade
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Nodes
<xs:element name="Students"> <xs:complexType> <xs:sequence> <xs:element name="Student" maxOccurs="unbounded"> <xs:complexType> ... </complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element>
<xs:element name="Semester-Course-Grades"> <xs:complexType> <xs:sequence> <xs:element name="Semester-Course-Grade" minOccurs="0" maxOccurs="unbounded"> <xs:complexType> ... </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> ...</xs:element>
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Nodes<xs:element name="Semester-Course-Grade" minOccurs="0" maxOccurs="unbounded"> <xs:complexType> <xs:attribute name="Semester" use="required"/> <xs:attribute ref="Course" use="required"/> <!-- C-XML: forall x (Course(x)=> exists [0:*] <x1, x2, x3> (Course(x) Student(x1) Semester(x2) Grade(x3) )) --> <xs:attribute name="Grade" type="xs:string" use="required"/> </xs:complexType></xs:element>
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Root Element
Students
Courses GradStudents UndergradStudents
<xs:schema > <xs:element name="Root"> <xs:complexType> <xs:all> <xs:element ref="Students"/> <xs:element ref="Courses"/> <xs:element ref="GradStudents"/> <xs:element ref="UndergradStudents"/> </xs:all> </xs:complexType> ... </xs:element> ...</xs:schema>
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Uniqueness Constraints<xs:element name="Students"> <xs:complexType> <xs:sequence> <xs:element name="Student" maxOccurs="unbounded"> <xs:complexType> ... </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> <xs:key name="StudentOID-Key"> <xs:selector xpath="./Student"/> <xs:field xpath="@StudentOID"/> </xs:key> <xs:key name="StudentID-Key"> <xs:selector xpath="./Student"/> <xs:field xpath="@StudentID"/> </xs:key> </xs:element>
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Generalization/Specialization
<xs:keyref name="UndergradStudentOID-Keyref" refer="StudentOID-Key"> <xs:selector xpath="./UndergradStudents/UndergradStudent"/> <xs:field xpath="@UndergradStudentOID"/> </xs:keyref> <xs:keyref name="GradStudentOID-Keyref" refer="StudentOID-Key"> <xs:selector xpath="./GradStudents/GradStudent"/> <xs:field xpath="@GradStudentOID"/> </xs:keyref>
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Transforming XML Schema to C-XML
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XML Schema C- XML
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Algorithm Overview Generate object sets for each element, attribute Specify built-in data types and simple types in the data
frame XML parent-child connections become binary
relationship sets minOccurs, maxOccurs, and use become participation
constraints
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Attribute Transformation
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Element Transformation
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Choice Transformation
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Sequence Transformation
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Key Constraints Transformation
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SubstitutionGroup & Extension
Transformation
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Observation on Transformations Our transformations to and from C-XML are not
inverses of one another However,
C-XMLXML Schema
C-XML XML Schema
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Observations & Recommendations
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C-XML is More Expressive than XML SchemaExtra, unneeded sequence structure
<xs:all> <xs:element name=“e1” maxOccurs=“3”> <xs:sequence> … </xs:sequence> <xs:choice> … </xs:choice></xs:all>
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C-XML is More Expressive than XML SchemaExtra, unneeded sequence structure
<xs:all> <xs:element name=“e1” maxOccurs=“3”> <xs:sequence> … </xs:sequence> <xs:choice> … </xs:choice></xs:all>
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C-XML is More Expressive than XML SchemaExtra, unneeded sequence structure
<xs:sequence> <xs:element name=“e1” maxOccurs=“3”> <xs:sequence> … </xs:sequence> <xs:choice> … </xs:choice></xs:sequence>
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C-XML is More Expressive than XML Schema
Generalization/specialization constraints
<!--C-XML:forall x (StudentOID(x) => UndergradStudentOID(x) or GradStudentOID(x))--> <!--C-XML:forall x (UndergradStudentOID(x) => not GradStudentOID(x))-->
<!--C-XML:forall x (Instructor(x) and Advisor(x)=> InstructorAdvisor(x))-->
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C-XML is More Expressive than XML Schema
Participation constraints for child elements
<!-- C-XML: forall x (State(x) => exists[0:*] y(State(x) has Order(2) in Sequence-k(y))) -->
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Recommendations
Extending XML Schema Extend the all structure Support generalization/specialization constraints
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XML Schema is More Expressive than Traditional Conceptual Models
Traditional conceptual model languages do not support: Sequence structure Choice structure Mixed-content Any and anyAttribute structures
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Recommendations
Enrich conceptual modeling languages Order lists of concepts Choose alternative from among several Specify mixed content Use content from another data model
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Conclusions Extended conceptual modeling for XML Developed transformation algorithms:
C-XML to XML Schema XML Schema to C-XML
Explored the equivalence of C-XML and XML Schema Basic transformations are not inverses But inverse transformations exist
Observations and Insights Expressive Power Recommendations
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Future Work
Provide mathematical proofs Make the prototype tool practical Continue with this work in several activities in
system analysis, design, development, and evolution XML database design and development Reverse Engineering Integration
