Information Technology Reference
In-Depth Information
For example in Fig.
8.5
the module
mars.fits
is not intelligible from ordinary
users (users with DC profile
u
2
). Therefore its intelligibility gap will be:
Gap
(
mars.fits
,
u
2
)
{
FITS Documentation
,
FITS SW
,
FITS Dictionary
,
JVM
}.
Notice that the modules that are already known from
u
2
(
PDF Reader, XML
Viewer
) are not included in the gap.
Clearly, if a module is already intelligible from a user, the intelligibility gap will
be empty i.e.
=
Gap
(
mars
.
fits
,
u
1
)
=
Ø.
Consider the file
HelloWorld.java
, shown in Fig.
8.8
. This file depends
on the modules
javac
and
Notepad
representing the tasks of compiling
and editing it correspondingly. Furthermore a DC profile
u
is specified con-
taining the module Notepad. Suppose that a user, having DC Profile
u
, wants
to edit the file
HelloWorld.java
. The editability of this file requires only
the module
Notepad
. However if the user requests for the intelligibility gap
(
Gap(
HelloWorld.java
,
u)
) it will contain the module
javac
even if it is not
required for the editability of the module. This motivates the need for type-restricted
gaps which are described below.
In general, to compute type-restricted gaps we have to traverse the dependencies
of a specific type. However since dependency types are organized hierarchically, we
must also include all the subtypes of the given type. Furthermore, the user might
request the dependencies for the performability of more than one task, by issuing
several dependency types.
Given a set of dependency types
W
, we define:
types
t
>
t
∩
t
>
W
t
iff
t
>
t
and
W
∗
=
Ø
where
types(t>t
)
is used to denote the types of the given dependency and
W
∗
(
a
)
(
b
)
is the set of all possible subtypes of the given set of types, i.e.
W
∗
=
∪
d
∈
W
{
d
. This means that
t>
W
t'
holds if
t>t'
holds and at least
one of the types of
t>t
belong to
W
or to a subtype of a type in
W
. Note that a depen-
dency might be used for the performability of more than one tasks (and therefore it
} ∪
d
|
d
d
Fig. 8.8
Dependency types and intelligibility gap
