In a data flow diagram, the segment shown below is identified as having…
2005
In a data flow diagram, the segment shown below is identified as having transaction flow characteristics, with p2 identified as the transaction center
A first level architectural design of this segment will result in a set of process modules with an associated invocation sequence. The most appropriate architecture is
Answer: C. A new module Tc is defined to control the transaction flow. This module Tc first invokes p1 and then invokes p2. p2 invokes either p3, or p4, or p5. — The DFD segment has transaction-flow characteristics. The incoming flow reaches the transaction center p2 through p1, and then p2 dispatches control to one of…
- A.
p1 invokes p2, p2 invokes either p3, or p4, or p5
- B.
p2 invokes p1, and then invokes p3, or p4, or p5
- C.
A new module Tc is defined to control the transaction flow. This module Tc first invokes p1 and then invokes p2. p2 invokes either p3, or p4, or p5.
- D.
A new module Tc is defined to control the transaction flow. This module Tc invokes p2. p2 invokes p1, and then invokes p3, or p4, or p5
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Correct answer: C
The DFD segment has transaction-flow characteristics. The incoming flow reaches the transaction center p2 through p1, and then p2 dispatches control to one of the action paths p3, p4 or p5.
In transaction-flow mapping, a transaction-control module is introduced at the architectural level. Let this controller be Tc.
The appropriate first-level architecture is:
Tc invokes p1, then Tc invokes p2, and p2 invokes one of p3, p4 or p5 depending on the transaction.
This preserves the incoming-flow part and the transaction-center dispatch separately. Therefore, option 3 is the most appropriate architecture.