Object-Relational and Object-Oriented Data Base MANAGEMENT SYSTEMS

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18 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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Slide
1

Đoàn Văn Ban

Object
-
Relational and

Object
-
Oriented Data Base
MANAGEMENT SYSTEMS

Slide
2

Chapter Overview


Data Base Management Systems


Traditional Database Systems


Object
-
Relational

Database Systems


Object
-
Oriented Database Systems


The Future of Object
-
Oriented Database
Management Systems

Slide
3

Data Base Management Systems: an Overview



Relational DBMS

Object
-
Relational


DBMS

Simple Data Complex Data

Query

No Query

File System

Object
-
Oriented


DBMS

Slide
4

Definitions


Database


A collection of data records organized to facilitate the
storage and retrieval of the data by information systems


Database management system


The software that runs a database


Almost all traditional database management
systems are relational


Data are stored in tables


The
primary key

labels primary records


The primary key can be used to label records in other
tables

foreign key

Slide
5

Traditional Database Systems (contd)


Information systems use a database management
system for


Writing of data to disk and


Retrieval of data from the disk



Examples:


Mainframe: DB2, Oracle, Informix, Sybase


Personal computers: Microsoft Access

Slide
6

Traditional Database Systems (contd)


Execution of the database instruction

Slide
7

Traditional Database Systems (contd)


Database instructions can be embedded within
many traditional programming languages


Including C and COBOL



Typical database instructions include


Retrieve


Insert


Delete, and


Update

Slide
8

Traditional Database Systems (contd)


The database management system manages the
database itself



The programmer writes code to


Invoke the database management system, and


Provide it with data it needs

Slide
9

Object
-
Oriented Database Systems


A company with a traditional database management
system is unlikely to use object
-
oriented database
management systems for some time


They are still too complex


An extensive background in object
-
oriented database
theory is needed


When an existing database is converted into an
object
-
oriented database


The existing traditional information systems cannot access
the new database


They have to be totally rewritten, at enormous cost

Slide
10

Object
-
Oriented Database Systems (contd)

Solution 1: Two databases


The one traditional, and


The other object
-
oriented


However, a major reason for using a database is to
have just one copy of each record



Two databases means having


Two copies of all data, and


Two versions of every new information system

Slide
11

Object
-
Oriented Database Systems (contd)

Solution 2: A hybrid system


An object
-
oriented information system interfacing with a
traditional database management system


Instructions are embedded in C++ or Java code


The database management system must


Manage the database (as before), and


Perform conversions from traditional to object
-
oriented
systems, and vice versa

Slide
12

Object
-
Oriented Database Systems


When writing data to the traditional database it must


Extract the data from an object


Convert the data into a record, and


Write the record to the traditional database



After retrieving a record from the traditional
database, it must


Insert the record into an object

Slide
13

Object
-
Oriented Database Systems

Solution 3: Object
-
Oriented Database Systems


The object
-
relational data base would contain the same
data stored in the relational database.


It would also accommodate the following more
complex data:



student photos


student voice print


Object
-
oriented model!


Object of class Student could extend an object of class
Person


Subclasses Doctoral_Student, Masters_Student and
Undergraduate_Student could inherit the methods of class
Student


Objects of class Course

Slide
14

Object
-
Relational DBMS


Introduced in 1992 with the release of the UniSQL/X unified
relational and object
-
oriented database system.


Then, Hewlett Packard released
OpenODB

(later Odapter),
which extended its AllBase relational DBMS.



In 1993, Montage Systems (later Illustra): shipped the first
commercial version of the object
-
relational
Postgres
.


SQL3 exists in draft form
--
anticipated ratification in July 1998.

Slide
15

Object
-
Relational DBMS

Key Players


Informix: Illustra (Informix
-
Universal Server)


UniSQL


Oracle: Oracle8


Hewlett
-
Packard


Unisys: OSMOS


IBM: DB2 version 3


Sybase: Adaptive Server (introduced Sept. ‘97)


Just released
--
a Java
-
based ORDBMS
:


Cloudscape’s JBMS

Slide
16

Object
-
Oriented DBMS

Suited for Complex Data


OODBMS allow better control of complex data and
complex interrelationships among objects.

Examples
:


Financial portfolio risk
-
analysis systems


Telecommunications service applications


WWW document structures


Design and manufacturing systems


Hospital patient record systems



The OODBMS integrates database capabilities directly into
the object
-
oriented programming language (C++, Smalltalk,
Java). This is different than SQL, which is a separate
language that defines, retrieves, and manipulates data.


Client is the C++ program


Server is the OODBMS

Slide
17

Object
-
Oriented DBMS

Developing Standards


The Object Database Management Group (ODMG):
standards
-
setting body, organized in 1991


Rather than defining a completely new standard from the
ground up, the ODMG standard builds upon the existing
OMG, SQL
-
92, and ANSI programming language standards
to define an application
-
portability framework among
OODBMS



ODMG
-
93: the answer to SQL


ODMG
-
93: an extension of the CORBA Persistent
Object Service

Three major components of ODMG
-
93
:


Object Definition Language (ODL)


Object Query Language (OQL)


C++ and Smalltalk language bindings

Slide
18

Object
-
Oriented DBMS

Standard: ODMG 2.0 (July 1997)



The Object Database Management Group (ODMG)
has published the ODMG 2.0 Specification, a key
milestone in the development of the only industry
standard for object databases.


The ODMG 2.0 standard includes
:


a new ODMG binding for Java that standardizes and
simplifies the storage of Java objects in databases


a metamodel that provides a language
-
independent
description of a database schema to tools and applications


improved C++ and Smalltalk language bindings

Slide
19

Object
-
Oriented DBMS

Real
-
world applications


ObjectStore by Object Design


The Human Genome Project
at the MIT Whitehead Institute (Cambridge,
MA) is helping to sequence the entire human genome by the year 2005. They
have two applications: MAPBASE (genetic mapping of mice) and LABBASE
(physical mapping of humans and mice), both of which use ObjectStore as the
data and model repository. They chose an OODBMS for the repository
because of its ability to efficiently and quickly manage complex genetic data.


Monterey Bay Aquarium Research Institute
uses ObjectStore to collect and
store multi
-
media oceanographic research data (videos, image, etc.). They
share their ObjectStore
-
based research data with other research organizations
through an extranet application written in Java. They replaced Oracle with
ObjectStore because ObjectStore reduced the amount of Java code required
(no need to convert their objects to rows & columns) and because ObjectStore
could be extended very easily to store any type of multi
-
media or textual data.


Slide
20

Object
-
Oriented DBMS

Real
-
world applications


Versant Object Technology


NUSTAR International
(Atlanta) uses Versant to accept, store, manage, and
publish data about real estate in many markets across the country. OODBMS
allows great flexibility for updating local editions
--
each of which includes
photos and other information about homes for sale in a given area.
Publications are updated very frequently. Company scans between 16,000 and
25,000 photos a week. Each photo is associated with a real estate listing that
includes text and graphics (including maps, floor plans, or logos).




Some DBMS developers define limitations of the OODBMS
as follows:


OODBMS are limited to small applications (small databases)


OODBMS don’t support a lot of concurrent users


It takes too much time to deliver an OODBMS application


Slide
21

Object
-
Oriented DBMS

Limitations? A Response

1997 study of 24 applications found that:


15 applications occupied between 1 and 99 GB


Four applications supported more than 500 users, with the most common
situation involving between 10 and 99 users.


Development can be time
-
consuming, but not in every case and delivery time
is improving (facilitated by greater availability of vendor tools). Twelve to
twenty
-
three months is average development period, but many companies
delivered in less than a year.


Relational DBMS market will grow to $6.8 billion by 1997, and $8.1 billion by
2000 (compared to $2.9 billion in 1995)


ORDBMS market will grow to $1 billion by 2000 (compared to $14 million in
1995)


OODBMS market will grow to $430 million by 1997 and $600 million by 2000
(compared to $100 million in 1995)


Conclusion
: Market for OODBMS is growing very fast, but still dwarfed
by relational DBMS


Slide
22

Object
-
Relational DBMS or

Object
-
Oriented DBMS? The Future.


Future databases (in perhaps 5 to 10
years) will likely be capable of
everything.



Relational DBs will likely be replaced with object
-
relational DBs.


Object
-
relational DBs are quickly adapting the
capabilities to deal with complex data (objects).


Object
-
oriented DBs are adding querying
capabilities similar to those of relational DBs.

Slide
23

Future of O
-
O Database Management Systems


Object
-
oriented database management systems will
become as easy to use as traditional database
management systems



It will still be too expensive to convert existing
databases and information systems to the object
-
oriented paradigm


However, new information systems will be written using
the object
-
oriented paradigm, but will interface with the
traditional database

Slide
24

Future of O
-
O Database Management Systems


New companies will use the object
-
oriented
paradigm for both


Its information systems, and


Its database management system


Legacy systems are the biggest obstacle to the
widespread utilization of object
-
oriented database
management systems


Just as they are to object
-
oriented information systems in
general


The object
-
oriented paradigm is the current choice
for the development of new information systems


This will lead to the adoption of object
-
oriented database
systems in the future


Slide
25

OODMS Web Sites


ObjectStore (
www.odi.com
),


GemStore (
www.gemstore.com
),


Objectivity (
www.Objectivity.com
),


O2 (
www.ardensoftawre.com
),


Jasmine (
www.cai.com
),


Versant (
www.versant.com
)


POET (
www.poet.com
).