Information Technology Reference
In-Depth Information
p
t
System A
1
Subsystem
B
Subsystem
C
Subsystem
D
Wire
Wire
p
p
p
2
3
4
AND structure in Petri nets
p
t
t
2
3
Module component E
Implementation
Implementation
p
p
6
7
Module G
Module H
OR structure in Petri nets
Figure 5.2
Modeling SCA function assembly through Petri nets.
5.3 ASSEMBLY PETRI NETS AND THEIR
PROPERTIES
5.3.1 Assembly and Disassembly Petri Nets
Assembly in SCA is the process of composing business applications by
configuring components that provide service functions. We transform
the assembly relationship in SCA into Petri nets, that is, transform
function combination and function selection to AND and OR structures
in Petri nets in Figure 5.2. The following definitions are used.
Definition 5.1.
A disassembly Petri net is an ordinary Petri net (
P
,
T
,
F
,
W
) with
M
0
and
M
f
as their initial and final markings, respectively,
satisfying the following conditions:
(i)
A place
p
0
2
P
is called a root such that it has no input
transition but has at least one output transition.
A subset of places
P
0
(ii)
P
are called a set of leafs such that
they have no output transitions, that is,
P
0
ΒΌ f
.
