Information Technology Reference
In-Depth Information
Based on the composition rules we have given in Section 3.2, we
give the definition of a service net and the method to derive it given a
service portfolio.
Definition 3.3. (Service Net, SN)
A service net
N
S
with respect to a
service portfolio and datamediation is a colored Petri net C
PN
¼
(
P
,
T
,
F
,
S
,
V
,
C
,
G
,
E
,
I
), where
1.
P
is a finite set of places.
2.
T
is a finite set of transitions,
T
T
M
where
T
O
is the set
of operation transitions, and
T
M
is the set of mediation ones.
3.
F
is a finite set of arcs.
4.
P
is a finite set of data types modeled as color sets.
5.
C
is a color function defined from
P
into
¼
T
O
[
S
.
C
is
injective
, that is,
p
2
.
6.
V
is a finite set of typed variables such that
Type
[
v
]
C
(
p
1
)
¼
C
(
p
2
)
)
p
1
¼
2S
for all
variables
v
2
V
.
7.
G
:
T
EXPR
V
is a guard function that assigns a guard to each
transition
t
such that
Type
[
G
(
t
)]
!
¼
Bool
.
8.
E
:
F
EXPR
V
is an arc expression function that assigns an
arc expression to each arc
f
!
2
F
such that
Type
[
E
(
f
)]
¼
C
(
p
)
MS
,
where
p
is the place connected to the arc
f.
9.
I
:
P
EXPR
1
is an initialization function that assigns an
initialization expression to each place
p
such that
Type
[
I
(
p
)]
!
¼
C
(
p
)
MS
.
This chapter focuses on the
structural
decomposition of service
nets guided by data types of places. Therefore, for simplicity, we will
use (
P
,
T
,
F
,
,
C
)or(
P
,
T
,
F
) to represent a net later.
A service net can be constructed in the following ways:
S
1. Data relations and mediations are modeled with mediation
transitions.
2. Service operations are modeled with operation transitions.
3. Places attached with an identical data type are merged into a
single one.
