For example, a transaction
may contain two activity groups. The first group executes a customer trading order, and the
second updates customer accounts (the activity section is discussed in the next section).
A transaction section is denoted by a dashed-line transaction frame, as depicted in
Exhibit 14.4. Note that this session contains two transactions??”transaction section 1 and transaction
section 2, each of which is also made up of activity groups. The former is composed of
three activity sections, and the latter contains a single activity group.
ACTIVITY SECTION. The activity section is where the sequences are described by which services
and consumers exchange messages and interact. This section is akin to Unified Modeling
Language (UML) sequence diagrams,9 in which message routing, remote call procedures (RPC),
time synchronization, and activity concurrency, are illustrated. Thus, this space is dedicated to the
most granular form of service interaction. For example, an activity can notify a mortgage consumer
about updated home loan rates. Another activity can invoke the customer records service
to provide a specific customer profile.
Consider Exhibit 14.5. It illustrates two transactions, each of which contains activity
sections. The depicted Transaction section 1 is composed of two activity sections: activity section
1 and activity section 2. However, Transaction section 2 includes only one activity group??”activity
section 1.
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