Pratt & Adamski chapter 9 & Some extra material

1. Pratt & Adamski chapter 9&Some extra material The Object-Oriented approach Object-Oriented DBMSs Semantic Object Models Spring 2012

2. Overview • Object-Oriented Systems • Class Diagrams • Unified Modeling Language (UML) • Object-Oriented DBMS • Semantic Object Models (SOM)

3. Object-Oriented Systems • View the world in terms of objects ("things") • • Easier to think of systems as objects (customer, shipping clerk,,) • • main driver: reusability • Object-orientation appears as: • • Object-oriented user interfaces (90% of new projects) • • Object-oriented programming (80% of new projects) • • Object-oriented databases (5% or less) • • OO analysis and design (30 to 40%)

4. Objects: Key Concepts • Definition: Objects are data guarded by a protective layer of code. OO Software components consist of variables and methods • Key concepts of the object-oriented paradigm: • object • attributes of objects • methods of object show behavior (what it can provide ) • class : template of objects • inheritance (lower level objects can inherit from higher level)

5. Objects: Key Concepts • Key Concepts (continued): • -Modularity (reduce complex systems into highly cohesive but loosely coupled modules) • -Encapsulation (Information hiding in implementation) • Message • Objects communicate via message passing. A message consists of an object (the recipient), a method, and optional parameters.

6. Object Examples • Example: items in a department store. • TV is an object. • The attributes of this object are model, year, cost, etc.The methods, for store are, purchase, repair • Radio is another object, so is a dishwasher • many of these objects have similar properties (attributes, methods) • can define a hierarchy .

7. Customer Smith: Customer Name Address Account No Balance Due -Smith -1109 Main St. -1100987546 -$589.19 Add-Customer() Update-Customer() Get-Balance-Due() Send-Invoice() Add-Customer() Update-Customer() Get-Balance-Due() Send-Invoice() Object Examples Class Object A Customer object is customer data and customer methods The attributes of customer object are Name, Address, Account No, Balance Due The methods on the customer object are Send-Invoice, Add-Customer, etc.

8. Resource Manage Resources Project Manager Resource Manager Hourly Salaried Manage Projects Unified Modeling Language (UML) • Unified Modeling Language (UML) • Original version released in 1996 • Became an International Standard in 1997 with the formation of UML Partners (HP, IBM, Microsoft, Oracle, Rational Software) • A graphical language for Object-Oriented Analysis and Design (OOAD) Class Diagram Use Case Diagram Sequence Diagram

9. Unified Modeling Language (UML) • Unified Modeling Language (UML) • 1. Use Case Diagram • 2. Class Diagrams • 3. Object Diagrams • 4. Sequence Diagrams • 5. Collaboration Diagrams • 6. Statechart Diagrams • 7. Activity Diagrams • 8. Component Diagrams • 9. Deployment Diagrams

10. Use-cases • Use cases describe the functionality of the system from the user point of view. • Each use case provides one or more scenarios of how the system should interact with the users called actors • Use cases are written in non-technical language, understood by users • Use cases are written as a part of requirement analysis. • Use cases are separate and distinct from use case diagrams, which allow one to abstractly work with groups of use cases. • Use case diagrams are created after the use case descriptions are written. Source: Dr. Sidorova, UNT

11. Use Cases Diagrams Depiction of a system’s behavior or functionality under various conditions as the system responds to requests from users <<include>> <<extend>> Source: Dr. Sidorova, UNT

12. Example of a use case diagram from Wikepidea Source: Dr. Sidorova, UNT

13. Class: Key Concepts • Class • A template or prototype that defines the composition and the behavior of all objects of certain kinds. These objects are called instances of the class • Inheritance • A mechanism to organize classes by commonalities. • subclasses, specialization • superclass, generalization • Example: • Student • GradStudent • MSStudent • PhDStudent • UGStudent

14. Point Class name x y Move methods p1: Point p2: Point x = 0 y = 0 x = 10 y = 10 Class diagrams • A class: point • An object: p1 • Attributes or fields: int x, y; • A method: point move(int dx, int dy) • A message: p2 = p1.move(10, 10) Fields (attributes)

15. Class Diagram details • Name of class • Attributes • Data types • Methods (operations) • Association (relationship) • Multiplicity (cardinality)

16. Class Diagram details • Associations are shown as lines joining classes and represent relationships. Multiplicity indicates the number of objects at the end of the relationship. Example: 1..1, 0..n, 1..n. • The visibility symbol indicates whether other classes can view or update attribute values: • Public visibility (+), any other class can view/update • Protected visibility (#), class itself or its subclasses can view/update • Private visibility (-), only class itself can view/update

17. Class Diagram for Premiere Products Figure 9.24

18. Class Diagram with Constraints Figure 9.25

19. Class Diagram with a Generalization and a Constraint Figure 9.26

20. Object-Oriented DBMS (OODBMS) • System in which data and the methods operating on that data are encapsulated into objects • Store graphics, drawings, video, sound, and other complex objects called binary large objects (BLOBs) • General concepts • Objects and classes • Methods and messages • Inheritance

21. Rules for OODBMSs: what they should support • Complex Objects • Object Identity • Encapsulation • Information Hiding • Types (classes) • Inheritance • Late Binding (polymorphism) • Computational Completeness • Extensibility • Persistence • Performance • Concurrent Update support • Recovery support • Query facilities

22. Semantic Object Model (SOM):a different approach

23. S-O MODEL CHARACTERISTICS • S-O Model More Bottom-Up-Oriented than the E-R Model • Both Are a Type of "Pseudo-Code“ or "Flowchart" Tool For DB Design • David Kroenke primary developer of the SO Model (1994). • The Model Is Robust But Lacks Standards. • NOT Widely Used Yet in CASE Tools.

24. S-O MODEL DEFINITIONS • * Semantic Object • * Object Identifier (primary key) • * Object Properties or Attributes • * Semantic Object Links • * Formulas

25. S-O MODEL DEFINITIONS • * Semantic Objects -- Represented by a Rectangle (See Fig B.2.a) • A named collection of Properties that sufficiently describes a distinct entity (Things, Objects (Nouns) Of Importance To The Users' Data Model) • E.g., Employee, Customer, Inventory, Order, Etc. • Instance Of A Semantic Object (Fig B.3) • Professor “Nick Evangelopoulos” • Semantic Object Classes -- • Collections Of Same Types Of Objects

26. Object Diagram Fig. B.2

27. Figure B.3Instance of a Semantic Object

28. S-O MODEL DEFINITIONS • * Semantic Objects are Distinct Entities -- • There are NO “weak” semantic objects! • Consider the relational DB design of an ordering system: Line_Item would be property of ORDER, not a distinct entity. • Semantic Objects are ALWAYS independent!! • Names in CAPITAL letters • Semantic Objects: • Must Exist In The Minds Of The Users-- • This is Why They Are Called Semantic Objects

29. S-O MODEL DEFINITIONS • Object Identifier: • Identifies A Unique Object Instance (Key) • May Be a Group or Composite (concatenated) Key (OrderNum, LineNum), (Cust_Name, Cust_Addr) • ID NameMixedCase • ID UniqueId when underlined

30. S-O MODEL DEFINITIONS • * Properties (Or Attributes) -- Fig B.2 Characteristics Of Semantic Objects: • Simple Data Values (S) • Multi-Valued (MV or 1.N) • Composite or Group Attributes (G) • Object attributes or Semantic Object Links(SOLs); • (see below) • Paired attributes: If an object contains another object, the second object will contain the first [SOLs are reciprocal] • USE Mixed Case for Naming Convention: DeptId

31. Figure B.2 (b)Cardinalities (Min.Max)

32. S-O MODEL DEFINITIONS • * Semantic Object Link (SOL) • Special Type of Property • Recursiveness • Represented by a rectangle inside of the SO • * Formulas (F) • Formula Functions: SUM, COUNT, MIN, MAX, AVG • Formula Expressions: e.g., Salary / 12

33. Figure B.2 (a) & (b) SOLs

34. S-O MODEL DEFINITIONS (Misc..) • Property Domains • Set Of All Possible Values Of A Property • Semantic Object Views (Fig. B.4) • Subset Of Properties Of S-O Required By A Particular Application Or User. Synthesis Of Multiple Objects • Views Required To Build Complete Object Diagram.

35. Figure B.4Semantic Object View

36. S-O DIAGRAMS Guidelines • Picture Of User’s Defined Objects • Non-Standard notation • Rectangles for Objects; NAMES in Capital letters inside rectangle • Object Properties written in MixedCase • SOLinks -- Written in Capital letters inside their own rectangles within the SO • Groups (Composites) properties are bracketed or braced on Right-hand side

37. S-O DIAGRAMS Guidelines (continued) • Multi-valued property Cardinalities are shown as Subscripts: • 1.1, 1.N, 0.1, 0.N, etc. (also, MV) • Actually Minimum and Maximum Cardinality for each property (ID, S, G, or SOL) • Min.Max The minimum and maximum allowable occurrences for each property. • 0.1 means that the property may have no instances, but at most 1. • 1.N means that the property must have at least one instance, and could have many instances.

38. Figure B.2 (b)Cardinalities (Min.Max)

39. Summary • Object-Oriented Systems • Class Diagrams • Unified Modeling Language (UML) • Object-Oriented DBMS • Semantic Object Models (SOM)