Lecture9 - 01/11/12 Lecture 9 on Object-Oriented Database...

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Unformatted text preview: 01/11/12 Lecture 9 on Object-Oriented Database To study object-oriented database as a 3 rd generation post relational database, its powerful features of inheritance, encapsulation, polymorphism, object identity, stored object identity, class, and method, and object, and above all, how it differentiates with relational database. 01/11/12 Motivations for Object-Oriented Database Systems - Serious Deficiencies in Current Database Systems - Promise of Object-Oriented Paradigm for Application Development - Application Productivity Enhancement - Offloading of Functions from Applications to Database Systems. e.g. Putting programs inside database (encapsulation). 01/11/12 Evolution of Database Systems- File systems e.g. ISAM, VSAM- Hierarchical Database Systems (e.g. IMS, System 2000)- CODASYL Database Systems (e.g. IDS, Total)- Relational Database Systems (e.g. DB2, ORACLE, SYBASE, INFORMIX).- Extended Relational Database (e.g. UniSQL)- Object-Oriented Database (e.g. GemStone) 01/11/12 Conventional Database Technology: Applications Perspective- Developed for Traditional Business Data Processing- Problematic for Many Non-Traditional Applications, e.g. Multimedia, Engineering, Design, Modeling/Analysis, Geographical, Moledular Biology, Statistical, etc.- Application Developers must do what database systems do not do. e.g. time- consuming and error-prone, potentially repeadted for each application 01/11/12 Conventional Database Technology: Serious Deficiencies- Due to Data Model. e.g. Fixed Data Types (integer, real, string, date, time, money, BLOB).- No Compound Data (complex nested data)- No Procedural Data (programs)- Single Value per Row/Column- Cannot Support Memory Pointer - Chasing Applications (navigate data via memory pointers) 01/11/12 Motivations for Object-Oriented Programming- Software Productivity- Development, Maintenance, and Evolution of Complex Software Systems.- Encapsulation (Data and Program)- Reuse (Inheritance) 01/11/12 Object-Oriented Concepts- Encapsulation- Object = Data + Program- Data = Values of Attributes (Row of a Table)- Program(Method) = Operates on the Data- Value of an Attribute can be an Object as well as a primitive value (number, string) 01/11/12 Example: Object Definition SHAPE attributes: Center-Point Point, Bounding-Box Box, Area Float methods: Display-Shape POINT attributes: X Float, Y Float BOX attributes: X1 Float, Y1 Float, X2 Float, Y2 Float 01/11/12 Example: Stored Representation SHAPE object POINT object Center-Point Bounding-Box Area Display-Shape X Y X1 Y1 X2 Y2 BOX object Display-Shape Code 01/11/12 Reuse - Attributes and Methods Inherited by Other Objects SHAPE TRIANGLE (Display-Shape) RECTANGLE (Display-Shape) (Display-Shape) 01/11/12 Organization of Objects- Organization of Objects- Objects (Instances) Are Grouped into a Class (Table)- Class: Attributes (and Data Types) and Methods 01/11/12 Classes are organized in a class hieraarchy (DAG)- Reuse (Inheritance) Superclass Subclass Single vs. Multiple InheritanceSingle vs....
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Lecture9 - 01/11/12 Lecture 9 on Object-Oriented Database...

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