Information Technology Reference
In-Depth Information
Algorithm 1.
Algorithm to initialize an object life cycle, call Algorithm 2 from a
reachability graph and post-process nodes already processed in Algorithm 2 (RG2OLC)
1:
IN:
RG
DP N
=(
N,M,T
RG
);
WRITERS
BP
2:
OUT:
S
OLC
;
T
OLC
;
WARN⊆ N
3:
S
OLC
←{START STATE}
;
T
OLC
←∅
4:
INPUT ←
(
WRITERS,firstNode,START STATE,∅, ∅, ∅, ∅,S
OLC
,T
OLC
)
5: (
S
OLC
,T
OLC
,PNODES,PP,WARN
)
← RG
2
OLC
(
INPUT
)
6:
found←
1 // Post-processing of nodes in PP
7:
while
found
=0
do
8:
found←
0
9:
for all
(
node, assocPath
)
∈ PP
do
10:
for all
(
s
i
,s
o
,path
)
∈ T
OLC
do
11:
if
node ∈ path
then
12:
found← found
+1;
newT ←
(
s
i
,s
o
,path
)
13:
T
OLC
← T
OLC
replace
(
newT, node, assocPath
)
14:
end if
15:
end for
16:
end for
17:
end while
18:
return
(
S
OLC
,T
OLC
,WARN
)
Its behaviour consists of calling Algorithm 2 with the appropriate parameters
and post-processing the resulting reachability graph. Algorithm 2 is a recursive
algorithm that builds an OLC by processing a reachability graph node by node
from its start node. Its input set and steps are described below.
Input of Algorithm 2.
-
WRIT
⊆
E
is the set of activities that write the data object.
-
cNode
∈
N
is the node being processed.
-
cState
D
is the current state of the data object.
-
PNODES
∈
⊆
N
is the set of already processed nodes.
-
PATH
N
contains a set of nodes of the reachability graph, which is
the information required in the transitions of the object life cycle.
-
PP
=
⊆
{
pair
1
,pair
2
, ..., pair
n
}
,where
pair
i
=(
node, assocPath
)
,node
i
∈
N
is a set of pairs containing a node of the reachability
graph and a set of nodes associated to that node, which conceptually
corresponds to the path contained in variable PATH when processing
that node.
-
WARN
N, assocPath
i
⊆
⊆
N
is a set of nodes related to deadlocks in the Petri net.
-
S
OLC
⊆
S
OLC
is the set of states of the resulting object life cycle.
-
T
OLC
⊆
T
OLC
is the set of transitions of the resulting object life cycle.
Check for and add new transitions (lines 3-7).
A new transition of one of
thetypesshowninFigures5aand5bmustbeaddedtotheOLCincasethat
a new state of the data object is found in the reachability graph. If, on the
contrary, the node shows that the data object is still in the current state but
