CS302: Software Engineering

Rules for Specifying Programs 

The specification documents all known information about programs. Program specifications document the program's purpose, process requirements, the logical and physical data definitions, input and output formats, screen layouts, constraints, and special processing considerations that might complicate the program. Keep in mind that the term program might also mean a module within a program or an externally called function, or even a code fragment (e.g., DB call). A program specification should include the items shown in Table 8-7. As with program packaging, there are no 'rules.' Rather there are items that should be included if they relate to the item being specified. 

There are two parts to a program specification: one identifies interprogram relationships and communication, the other documents intraprogram processing that takes place within the individual program. Interfaces to other programs generally document who, what, when, where, and how communication takes place. Who identifies who initiates the communication and who, in the real world, is responsible for the interface. What identifies the message( s) content that is used for communication. When identifies the frequency and timing of the interface. Where locates the application and system in a hardware environment; where becomes complicated and is crucial to processing of distributed applications. How describes the nature of the interface-internal message, external diskette, and so forth.

Internal program processing information includes the data, processes, formats, controls, security, and constraints that define a particular program. Frequently, program specifications also include a flowchart of the program logic, a system flowchart showing the system names of the files, and a detailed specification of timing and other constraints. 

FIGURE 8-32 ABC Video Processing Focus Mainline

FIGURE 8-32 ABC Video Processing Focus Mainline

ABC Video Example Program Specification 

The program specification for one program to perform Get Valid Customer is shown as an example (see Table 8-8). Since this is a compilation of already known information there is no discussion.