7
Table 2. 1
Element Used in Use Case Diagram
Actor
An actor
represents
a
set
of
roles
that
a
user
plays
with
an
entity
(system, subsystem or a class). Actors can be human or other systems,
subsystems or classes that represent things outside of the entity. The
actor "communicates" with the entity by sending a series of messages
backwards and
forwards.
Use Case
A
use
case
is
a
related
sequence
of
steps
or
scenario
both
automated
and manual for the purpose of completing a single business task.
Actor-Use case Association
An association
is
a
semantic
or
structural
relationship
between
classifiers.
An
association
has
a
name
and
consists of at least two
association ends. The association ends are simply the end parts of the
association
where
they
connect
to
classifiers.
It
is
the
association's
ends that may have a number of adornments that express the rich
structural semantics of the
relationship.
Include
Include is
a
relationship
that
may
exist
between
two
use
cases,
a
base
use case and an addition use case. It
means a base
use case
may
insert
behavior from an addition use case. The relationship is said to be
unconditional
in the sense that
if
the
insertion occurs; all
the behavior
of the addition
use case
is unconditionally
inserted.
Extend
Extend is a relationship that may exist between two use cases, the base
use
case
and
the
extension
use
case.
The
extension
use
case
is
made
because
you
want
to
simply
the
use
case
and
make
it
more
easily
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