Information Technology Reference
In-Depth Information
2.2.3 If there is no m
00
2
V such that m
00
¼
m
0
, then V
¼
m
0
g
;
(and m
0
is untagged)
V
[f
m
0
Þg
2.2.4 E
¼
E
[fð
m
;
t
i
;
2.2.5 If t
i
\
p
m
(i.e., new tokens are fed into mes-
sage place p
m
with the firing of t
i
)
(a) Flag all the rows whose source message is C
P
Mi
¼
ð
p
m
Þ
in the data mapping table
(b) Compute m
00
such that m
0
!
m
0
Þ
m
00
. m
00
is derived
from m
0
through virtual transition t
M
ð
t
M
ð
m
0
Þ
by (i)
unmarking p
m
if in all data mapping rules whose
source message is C
, the target messages are
satisfied, (ii) marking the place attached with the
message, for each newly satisfied target message
in step (a). (Note that a target message is satisfied
if in the data mapping table all the rows it resides
in are flagged.)
(c) If m
00
ð
p
m
Þ
m
0
: tag m
0
; V
m
00
g
6¼
¼
V
[f
; E
¼
E
[
m
0
;
m
0
Þ;
m
00
Þg:
(and m
00
is untagged.)
fð
t
M
ð
Gð
;
;
Þ
3. The algorithm succeeds with
N
1
N
2
I
obtained.
Given eBay service N
1
, TPC service N
2
in Figure 4.7, and the data
mapping I in Table 4.2, we can derive
Gð
Þ
according to
Algorithm 4.1 as Figure 4.8 shows. The operation edges are denoted
with solid directed arcs and the names of operation transitions are
labeled on them. The mediation edges are denoted with dashed directed
arcs, and the data obtained by mediation are labeled on them. The first
several steps to obtain the CRG in Figure 4.8 are as follows. At the
beginning, eBay and TPC services are both at the initial state, with a
token in p
1
and p
14
, respectively. Other places are with no token except
p
10
that represents TPC.COReq.PartnerID with a token representing a
constant value “eBay”. Starting from this initial state denoted by
the initial bold ellipse in Figure 4.8, the eBay service can fire its
“Invoke TPC” transition and deposit a token to p
2
and p
5
, respectively
as seen in the second ellipse. At this state, by checking Table 4.2 we
can find that both parts of TPC.COReq,thatis,Order and PartnerID
are available, and eBay.(UserID, SecretID) is also available. Hence, a
mediation transition can fire to deposit a token to p
6
and p
11
,
N
1
;
N
2
;
I
