1. Applications of ORA-SS: An Object-Relationship-Attribute Model for Semistructured Data
Tok Wang Ling1
Mong Li Lee1
Gillian Dobbie2
1Department of Computer Science, National University of Singapore
2Department of Computer Science, The University of Auckland, NZ

2. Content
Part I ORA-SS: An Object-Relationship-Attribute Model for Semistructured Data
Object class
Relationship Type
Attribute
Semistructured data instance
Functional dependencies and other constraints
Inheritance hierarchy
Part II Research Topics using ORA-SS Model
Normal form ORA-SS schema diagram
Storage schema for ORA-SS/XML databases
ORA-SS/XML views
Evaluating XML queries on ORA-SS databases
Translating relational schema into ORA-SS schema
Integration of XML documents

3. Motivation Figure 1: Sample instance demonstrating OEM and dataguide
▼♦ department
▼♦ student
▼♦ course
♦ name
♦ number
♦ student number
♦ grade
department cs
student
number
name
computer science
&3
&1
course
&20
&21
&22
grade
1234
B.Y.Smith 70
1235
C.U. Brown 60
cs4221
Database
&26
&7
&4
&2
&5
&6
student number
&23
&24
&25
&27
&28
(B) Dataguide
(a) OEM Diagram
Figure 1: Sample instance demonstrating OEM and dataguide

4. Figure 2: ORA-SS instance diagram
Motivation (cont.)
department
Number: CS
Name:
Computer
Science
course
course
student
student
Number
Name
Student
Number:
CS4221
Name:
Database
student
number
department
course
2, 1:n, 1:1
name
grade cs
Student
number:
1234
Name:
B.Y. Smith
Student
number:
1235
Name:
C.U. Brown
Grade: 70
Grade: 60
Figure 2: ORA-SS instance diagram
Figure 3: ORA-SS schema diagram

5. Object class Relationship Type attributes of object class
ORA-SS The Data Model
Object class
attributes of object class
ordering on object class
Relationship Type
attributes of relationship type
degree of n-ary relationship type
participation of objects in relationship type
disjunctive relationship type
recursive relationship type
symmetric relationship type

6. ORA-SS The Data Model (cont.)
Attribute
key attribute
degree of n-ary relationship type
composite attribute
disjunctive attribute
attributes with unknown structure
ordering on attribute
fixed and default values of attribute
derived attribute
Semistructured data instance
Functional dependencies and other constraints
Inheritance hierarchy

7. The data model of ORA-SS Object Class
attributes of object class
ordering on object class
student
number
first name
last name
Figure 4: Object class student with attributes
in an ORA-SS schema diagram

8. The data model of ORA-SS Relationship Type
attributes of relationship type
degree of n-ary relationship type
participation of objects in relationship type
disjunctive relationship type
recursive relationship type
symmetric relationship type
project id
name
member
job title
publication
number
title
2, +, +
2, *, + p1 p2 p3 m1 m2
pub1
pub2
pub3
project
member
publication
♦ number
▼♦ publication
▼♦ project
▼♦ member
♦ name
♦ title
♦ job title
♦ id
(a) ORA-SS Schema Diagram
(b) Instance Relationship
(c) Dataguide
Figure 5: Representing binary relationship type

9. The data model of ORA-SS Relationship Type (cont.)
pub1
pub2
pub3
project
member
publication
project id
name
member
job title
publication
number
title
2, +, +
3, *, +
(b) Instance Relationship
♦ number
▼♦ publication
▼♦ project
▼♦ member
♦ name
♦ title
♦ job title
♦ id
(a) ORA-SS Schema Diagram
(c) Dataguide
Figure 6: Representing ternary relationship type

10. The data model of ORA-SS Attribute
key attribute
degree of n-ary relationship type
composite attribute
disjunctive attribute
attribute with unknown structure
ordering on attribute
fixed and default values of attribute
derived attribute
course
student *
code
title
ANY
dept prefix
D: comp
number
first
name
last
mark
grade cs
2, 4:n, 3:8
hobby
Figure 7: Object classes with relationship type and attributes
in an ORA-SS schema diagram

11. The data model of ORA-SS Ordering
the instances of an object class can be ordered,
the values of an attribute can be ordered, and
the set of attributes of an object class can be ordered
book *
content
chapter
paragraph
title
author
preface
toc
text
2, 1:1, 1:1
<
cc,
3, 1:n, 1:1
4, 1:n, 1:1
<
<
Figure 8: Ordered object classes and attributes
in an ORA-SS schema diagram

12. The data model of ORA-SS Disjunction
disjunctive object class, and
disjunctive attribute.
course
cs,
2, 4:n, 3:8
exam
venue
code
title
student
address, 2, ?, +
lecture theatre
laboratory cs
student
number
name
grade
hostel
home
street
name
name
number
Figure 9: Disjunctive attribute and relationship type
in an ORA-SS schema diagram

13. The data model of ORA-SS References
course
student
code
title
grade
faculty
name
fs,
2, 1:n, 1:n *
history
hostel
home
cs,
2, 4:n, 3:8
street
number cs
student number
course
code
grade
name
Figure 10: Referencing an object class in an ORA-SS Schema Diagram

14. The data model of ORA-SS References (cont.)
course
2, 0:5, 1:n
course
code
title
Figure 11: Example of a recursive relationship type
in an ORA-SS Schema Diagram
student
course
cs,
2, +, +
2, +, +
student
course
course
number
name
number
of students
student
number cs
grade
Figure 12: Symmetric relationship types in an ORA-SS schema diagram

15. The data model of ORA-SS Reference (cont.)
student
sc,
2, 3:8, 4:n
name
course
ct,
2, +, + sc
sct,
3, 1:1, 1:n
tutor
code
title
grade ct
tutor
sct
hours
name
office
feedback
hostel
home
building
room
name
number
street
Figure 13: ORA-SS schema diagram

16. The data model of ORA-SS Reference (cont.)
student sc
course ct
feedback
sct
hours
tutor
name
office
building
room
hostel
home
number
street
grade
code
title
3:8
4:n
1:1
1:n
UNION
address ta
Figure 14: ER diagram of schema in Figure 13.

17. The data model of ORA-SS Functional Dependencies
student, course  tutor
tutor  course
1/n
n/1
n/_
student
course
tutor
sct
Figure 15: Functional dependencies diagram

18. The data model of ORA-SS Inheritance Hierarchy
person
payrate
degree
student
tutor
ssn
number
3,+,+
grade
title
sc,
2,+,+
student
number
course
faculty
tutor
ssn
payrate
degree
ssn
faculty
staff
number
Student
number
(b) Inheritance Diagram
staff
number
student
number
(a) ORA-SS Schema Diagram
Figure 16: ORA-SS schema diagram and inheritance diagram

19. The data model of ORA-SS Constraints
Inclusion dependency
Semantic dependencies
2,1:1,1:n
jdate
name
ssn
department
employee ?
number
ed,
2,1:1,1:n
jdate
name
ssn
department
employee ?
number ed
(a) Date of employee joined company
(b) Date of employee joined department
Figure 17: Modeling join date (jdate) ORA-SS schema diagram

20. Research Topics for ORA-SS Model
Normal form ORA-SS schema diagram
remove redundant data
resolve class hierarchy conflicts
Storage schema for ORA-SS/XML databases
use Object Relational Model
ORA-SS/XML Views
derived information from references and class hierarchy
defining views
materialized view maintenance
view updates
Evaluating XML queries on ORA-SS databases
XML schema to ORA-SS Schema
XML document to ORA-SS database
Translating relational schema into ORA-SS schema
Integration of XML documents

21. Research Topics for ORA-SS Model Normal Form ORA-SS Schema Diagram
Schema may have a lot of redundant data
Update anomalies
Normal Form schema is needed
title
author
ISBN 2
professor
textbook
staff#
name
course
C.Code +

22. Research Topics for ORA-SS Model NF ORA-SS Schema Diagram (cont.)
Some better solutions:
Redundancies are removed, in normal form
ISBN
title
author
professor
textbook
staff#
name
course
C.Code +
C.Code
title
ISBN
author
professor
textbook
name
course +
staff#

23. Research Topics for ORA-SS Model Storage Schema for ORA-SS/XML Databases
Main Rules
Each object class together with its attributes form a nested relation (object relation)
Each relationship type together with its attribute form a nested relation (relationship relation)
Nested relations can be handled by Object Relational model, e.g. ORACLE 8i.

24. Supplier (S#, Name, (City)) Part (P#, Name, color)
Research Topics for ORA-SS Model Storage Schema for ORA-SS/XML Databases
Object Relations
Supplier (S#, Name, (City))
Part (P#, Name, color)
Project(J#, Name, Loc)
Relationship relations
SP (S#, P#, price)
SPJ (S#, P#, J#, Qty)
Constraint:
SPJ[S#, P#]  SP[S#, P#]
Price SP
SPJ 3
Loc
City
Name J# 2
Supplier
Project
Part +
Color
Qty S# P#

25. Research Topics for ORA-SS Model Views
What information can be directly derived from references and class hierarchy
code
faculty
grade
history fs cs
fs,
2,1:n,1:n
name
title
cs,
2,4:n,3:8
course
student
number *
street
hostel
home |
street
number
name cs
title
course
code
student
grade |
hostel
home
Referencing an object class in an ORA-SS schema diagram

26. Research Topics for ORA-SS Model Views (cont.)
Valid views of an ORA-SS schema
Operations: selection, projection, join, up/down
Supplier
Part
Project
Project 2 2 2
Part
Supplier
Part
Part 2 2 3 3 2 2 3
price
price
Project
Project
Supplier
total_qty 2 3 3 3
price
Qty
Qty
Qty
View 1
View 2
View 3

27. Research Topics for ORA-SS Model Views (cont.)
Views from ORA-SS storage schema
Main Rules
The order of the object classes in a relationship relation can be changed.
Object classes can be dropped from a relationship relation. In this case, the attributes of the relationships will have different cardinalities or change to some aggregate functions such as sum, max/min, average, etc.
Other Topics on Views
materialized views and maintenance
view update problem

28. Related issues: Map XML schema to ORA-SS schema
Research Topics for ORA-SS Model Evaluating XML queries on ORA-SS Databases
Related issues:
Map XML schema to ORA-SS schema
Extra information is needed
Map ORA-SS schema to storage schema (OR model)
Map XML documents to ORA-SS databases
(using object relational model DBMS)
Map XML queries to queries on the ORA-SS databases
Need to handle recursions and wildcard such as *(any), |(or), !(not), etc.
Result construction, i.e. to XML documents

29. Extra information needed:
Research Topics for ORA-SS Model Translating Relational Schema into ORA-SS Schema
Extra information needed:
FDs and keys
Inclusion dependencies
Semantic dependencies
Main steps:
Identify object classes and their attributes from object relations
Identify relationship classes and their attributes from relationship relations
Identify class hierarchy
Identify non key constraint functional dependencies
Generate ORA-SS/XML Views for applications.
Similar to translating relational schema to OO schema

30. Applications of ORA-SS Summary
Introduced ORA-SS model
Briefly discussed research topics using ORA-SS Model
Normal form ORA-SS schema diagram
Storage schema for ORA-SS/XML databases
ORA-SS/XML views
Evaluating XML queries on ORA-SS databases
Translating relational schema into ORA-SS schema