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Object-Oriented Data Bases - Coggle Diagram
Object-Oriented Data Bases
Motivation for Object Database Management
digital storage
cheaper
more reliable than traditional means such as paper, film, etc.
allows retrieval and manipulation
Object Technology(
OT
) has been dominating the softwae engineering industry in recent times.
Object-oriented methodologies(
OOM
) provides obvious advantages to application programming
with benefits of
encapsulism
polymorphism
complexity(information) hiding
code reusability
object-oriented approach is preferable for certain scenarios
CAD
Multimedia systems and CASE tools
GIS(Geographic information systems)
Document storage
Retrieval systems
Overview of Object-Oriented Database Management Systems
object-oriented software system hold following concepts
object type is a concept of thing about which data is to be stored
object is an instance of an object type
operation is a set of actions to be performed on an object
method specifies the way an operation is to be performed
encapsulation is the packaging of data structure and operations
inheritance: a subclass\may inherit properties
polymorphism is the phenomenon where a given object or operation may take on a different form
objects communicate by sending messages to each other
Architectures for Object Database Management
Large objects and External Software
complex data a large text document uses the CLOB data type
large objects usually are stored separately from other data in a table
large object approach is simple to implement and is universal
Specialized Media Servers
complex data reside outside if a DBMS
Programmers use an application programming interface (API) to access complex data through a media server.
API provides a set of procedures to retrieve, update, and transform a specific kind of complex data
combining simple and complex data, the specialized server approach may perform poorly
media server may not provide indexing techniques for search conditions
Object Database Middleware
relieves the user of knowing a separate API for each media server
clients send SQL statements to middleware
sends SQL statements to database servers
makes API calls to media servers
circumvents problems with media servers by simulating object features
provides location independence because users do not need to know where complex data reside
provides a way to integrate complex data stored on PCs and remote servers with relational databases
can suffer performance problems because of a lack of integration with a DBMS
Object Relational Database Management Systems for User-Defined Types
With larger changes to a DBMS, more query and optimization capabilities are possible
To provide additional query capabilities
any kind of complex data can be added as a user-defined type
User-defined types involve a table-driven architecture
object query processor uses table-driven code for user-defined types
Object-relational DBMSs provide good integration of complex data, but reliability may be a concern
Object-Oriented Database Management Systems
The software companies have banded together to form the Object Database Management Group (ODMG)
ODMG has proposed an object definition language (ODL) and an object query language (OQL)
preceded object-relational technology offerings by 10 years
object-oriented DBMSs have provided ad hoc query, query optimization, and efficient transaction support