Thus, the in-order service synchronization centers on
activity priorities rather than on service cardinality or visibility aspects, which were discussed
previously. In a nutshell, the focus here is on message dependency aspects of a business or
technological process.
Why the dependency concerns? The in-order service synchronization method often introduces
performance challenges, because services must halt their operations until a response is
received; this is known as blocking mode. Think about a business transaction that must be executed
on time and must follow a set of steps in a certain predefined sequence. Take, for example, a business
that depends on client information before it delivers its goods, as depicted in Exhibit 12.13.
The illustrated distribution center consumer must first identify the customer by retrieving its pro-
file and obtaining its address. The second activity invokes the U.S. maps atomic service to learn
the customer??™s physical location. Finally, a customer order must be placed by calling upon the
248 Ch. 12 Service-Oriented Logical Design Relationship
Customer
Profile Atomic
Service
US Maps
Atomic
Service
Distribution
Center
Consumer
Place
Order
Atomic
Service
1
2
3
EXHIBIT 12.13 IN-ORDER SERVICE SYNCHRONIZATION
place order atomic service. This logical process execution ought to be synchronized to enforce a
sequence of activities that depend on each other to enable the successful ordering of a product.
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