Consider a legacy, fax-based, problem-reporting system for an aircraft manufacturer. You are part of a reengineering project replacing the core of the system by a computer-based system, which includes a database and a notification system. The client requires the fax to remain an entry point for problem reports. You propose an E-mail entry point. Describe a subsystem decomposition, and possibly a design pattern, which would allow both interfaces.

What will be an ideal response?


There are two main approaches to this problem. The first approach is to design the system with an E-mail frontend



and add a subsystem which converts fax problem reports to E-mail (possibly with the assistance of an actor). The E-

mail front end then becomes a single point of entry into the problem reporting system. The second approach (depicted



in Figure 7-2) is to provide a network level interface to the problem reporting system (e.g., using RPC, RMI,

CORBA, or plain sockets) and to build two different clients to the system, one processing E-mail, the other

processing fax reports. The first solution is cheaper to realize and would be appropriate if the fax front end is short

lived or no other frontends are planned. The second solution is more general and allows the addition of other

frontends in the future. Design goals defined during system design would be used to decide between these two

alternatives. The main point the student should realize is that there are alternative solutions to subsystem

decomposition issues and that design goals can be used to sort them out.



Computer Science & Information Technology

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