Information Technology Reference
In-Depth Information
Third-party
checkout
Mediator
eBay
p
14
p
1
COReq
Order
p
5
Order
Invoke TPC
Initiate TPC
p
11
(
UserID,
SecretID
)
p
2
p
10
p
15
Process
FetchToken
PartnerID
p
6
Invoke
GetOrderTrans
Token
(
OrderID, UserID
)
p
3
p
7
Token,
OrderID,
UserID
)
(
p
12
Process
GetOrderData
p
16
Process
OrderData
p
8
OrderData
Ack
p
17
p
9
(
p
13
)
p
4
p
18
Figure 4.12
Mediation-aided service composition.
reachability graph of N
1
P
C1
M
P
C2
N
2
is well-formed, that is, eBay and
TPC services are compatible with the aid of mediator
.
For mediator development/deployment, we use IBM Business Pro-
cess Manager [33]. A program takes the BPEL services defined as input,
transforms the BPEL services into SWF-nets, and analyzes their com-
patibility. If two BPEL services are partially compatible, a mediator Petri
net is generated and transformed back into a mediator BPEL service. The
mediator BPEL service consists of such activities as receive, assign,and
invoke and the links among them. Once all source messages are ready,
the target message is generated and the corresponding interface is
invoked. In our BPEL run-time, that is, IBM Business Process Manager,
each porttype is equipped with a message queue. Thus, the mediator can
simply forward the target message whenever all the source messages are
ready, being unaware of when the target messages will be consumed. The
mediator BPEL assembles the two original BPEL services and makes
them run smoothly with each other. Otherwise, if two services are not
compatible, our program can point out where the incompatibility is and
give instructions to correct the incompatibility, for example, by adding
data mapping or changing a message sequence.
M
