Based on these specifications, Software Engineering decomposes the computer procedure into one or more programs. During previous phases, rough designs of the programs were prepared. However, during this activity, final decisions are made. The computer procedure is defined in terms of:

• The number of programs needed to implement the computer procedure.

• The processing flow of the programs. This establishes dependencies between programs during execution (sequence, iteration, and choice).

• How inputs, outputs and files flow in and out of each program. This includes specifying how they are used in the program (Create/Update/Reference).

• Supplemental computer working files to pass data between programs.

The Computer Procedure Flowchart is used to represent the design. Following this, Software Engineering determines the most appropriate way to implement each program:

• Manually writing an unstructured program.

• Manually writing a structured program (modular, object oriented, or otherwise).

• Assembling a program through re-usable code. Modules and subroutines are cataloged in the IRM. Software Engineering should be able to easily locate such resources and be able to perform an "impact analysis" on them.

• Through a commercially available software package.

• Using computer utility programs (such as to perform a sort).

• Generating a program through such tools as code generators, report writers, fourth generation languages (interpreters), etc.

• Combinations of the above.

For additional information on "PRIDE" Graphics, see: "PRIDE" Flowcharting Symbols.

Each program is then specified in the IRM by number, name, timing (offset and response time), language, and memory requirements. If the program is to be decomposed into modules and subroutines (either new or existing), Software Engineering defines them in the IRM and establishes the necessary relationships between programs, modules, and subroutines. By the end of this task, all of the major components of each program have been defined to a degree that the Software Engineer is confident in the software design both from the point-of-view that it is a workable solution and that a Detail estimate/ schedule can be prepared for the remaining activities of Phase 4-II (B - E).

If a program is complicated, it may be necessary to spend some time in Activity A performing experiments to research and validate the software design. This should only be done in areas where the Software Engineer is unsure of the programming technique or if it is uncertain whether the computer can perform the process or not.

DELIVERABLES

The deliverables resulting from this activity include:

• Computer Procedure Flowchart (as described above).

• Computer Procedure Discussion - narrative describing the software design approach. Prior to Phase 4-II, Systems Engineering prepared text describing the purpose of the computer procedure, and general processing requirements. During this activity, Software Engineering updates the text accordingly.