Matakuliah
Tahun
Versi
: M0174/OBJECT ORIENTED DATABASE
: 2005
: 1/0
Pertemuan 7
The Object Definition Language
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Mahasiswa dapat Menjelaskan object
definition language (C2)
• Mahasiswa dapat Menjelaskan hubungan
antara ODL dengan bahasa program dan
database schema (C2)
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Outline Materi
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What is ODL ?
The structure of an ODL Schema
Class definition
Class header
Supertypes and extender classes
Type properties
Interface definition
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What is ODL ?
• ODL is one of a collection of language
which are used together to implement
object database system.
• The purpose of ODL is to define object
types which conform to the object data
model
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What is ODL ?
• Relationship
between ODL and
Other Programming
Language
Object databse application program written in a programming
language such as C++, Java
ODL definition of the interface between the applications and the
object database
Implementation of the object database types written in a
programming language such as C++, Java
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What is ODL ?
• Relationship of ODL to an Object Database
Schema & Application
ODL Object Database
Schema Type
Declaration and
Interface
Object Database
Application Program
Written in an Extended
Programming Language
Object Database
Schema Preprocessor
Programming Language
Compiler/Linker
Object Database
Application
Object Database
Management System
Runtime Library
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What is ODL ?
• Two further advantages of the
independence of ODL from specific
programming language:
– First the ability to port object database system
from one programming environment to other.
– Second the ability to operate many object
database system together, even when
different language have been used to
implement them.
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What is ODL ?
• The ability to define interface to object in a
way which is independent of the language
that are used to implement or utilize them
has a general use in distributed object
oriented environment.
• This ability makes it possible for many
application to share and utilize objects
which provide general service.
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What is ODL ?
• The rules for forming statements is ODL, are
given using a notation called extended BNF
(Backus-Naur Form) in which:
– The symbol “ ::= “ can read as ‘is defined as’
– The Part of an ODL statement are described in
angular brackets (e.g <type definition>), or as they
appear in the statement it self.
– Square brackets are used to denote optional parts of
an expression. An asterisk after the closing square
bracket “]* ” indicates the optional part can occur
many time.
– A vertical line is used to separate alternative parts of
an expression.
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The structure of an ODL Schema
• The purpose of an ODL Schema is to
enable application programs and tools to
create, access, and manipulate the
contents of an object database
• Examples
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Class definition
• A class definition defines the behaviour
and state of an object type
• Examples
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Class header
• Object types are themselves represented
as objects and therefore have properties
• The properties of an object type include its
supertypes, extender class, extent, and
keys
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Supertypes and extender classes
• A class may inherit from other object types
in two ways :
– A class may have zero or one extender class
– An object type (a class or interface) may also
have zero, one, or more interface which are
its supertypes from which it inherits behaviour
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Type properties
• The extent name
• The instance properties that are used as
keys
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Interface definition
• An interface definition has two main parts
– The interface header
– The interface body
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SUMMARY
• The ODL is the ddl for object database
• The approach contrasts with that of
persistent object oriented programming
languages
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