第
30
卷第
2
期
2001
年
4
月
电子科技大学学报
Journal
of
UEST
of
China
UML Modeling Mechanism
ßased
on Layered
Structure
of
Abstraction *
WuYue
Luo Wuman
(College
of
Cornputer
Science
and
Engineering
,
UEST
of
China
Chengdu
610054)
Vo
1.3
0
NO.2
Apr.2oo1
Abstract
刀山
paper
introduces
UML(Unified
Modeling
Language)
modeling
method.
ßased
on
the
experience
of
traditional
softw
缸巳
development
method
and
由
e
analysis
of
traditional
由
ree
layered
structure
of
abstraction
in
UML
,
two
ideas
of
abstraction
and
d
巳
composition
are
brought
forward
as
出
e
kemel
modeling
ideas
of
UML
to
construct
也
e
abstraction
modeling
mechanism
of
UML
that
generalizes
由
e
process
of
computer
system
into
the
process
of
picking
up
five
cells:
the
function
cell.
the
structure
cell
,
the
service
cell
,
the
implementation
cell
and
由
e
integration
cell.
Th
e
pu
甲
ose
is
to
make
use
of
也
e
whole
semantics
of
UML
effectively
and
to
get
over
the
limitation
of
traditional
00
method
and
eventu
a11
y
to
achieve
the
perfectly
transition
企
om
requirement
to
analysis
and
virtual
separation
of
旬
nction
and
implementation.
Key
words
unified
modeling
language;
abs
往
'action;
d
巳
composition;
layered
modeling;
cell
1 Some Concepts
of
UML
1.1 Use case
An use case is a coherent unit
of
functionality provided by a system or
c1
ass as manifested by
sequences
of
messages exchanged among the system and one or more outside interactors (called actors)
together with actions performed by the system.
1.2 Class
A
c1
ass is the descriptor for a set
of
objects with similar structure, behavior, and relationships. A
c1
ass
may use a set
of
interfaces to
speci
句，
collections
of
operations it provides to its environmen
t.
Class may be
abstract and executable.
1.3
Interface
An interface is a de
c1
aration
of
a collection
of
operations
由
at
may be used for defining a service
offered by an instance
of
class
(0
时
ect).
An interface serves to name a collection
of
operations and specify
their signatures and protocols. An interface offers no implementation (method) for any
of
its operations.
1.4
Package
A pac
1ca
ge is a group
of
model elements such
as
c1
asses. A package may contain both subordinate
pac
1ca
ges and ordinary model elements. Some packages may be subsystems or models. The entire system
description can be thought
of
as a single high-level subsystem package with anything else in i
t.
1.
5
Component
A component is a non-trivial,
ne
町
ly
independent and replaceable
p
缸
t
of
a system that fulfills a
c1
ear function in the context
of
a well-defined architecture. A component conforms to and provides the
physical realization
of
a set
of
interfaces. A component may be one or more class.
Received
on
July
28
,
2000
*
The
project
supported
by
the
Acadernic
Foundation
of
Nu
c1
ear
Physics
of
China
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