Chapter 13 Finalizing Design Specifications Modern Systems Analysis and Design Fifth Edition Jeffrey A. Hoffer Joey F. George Joseph S. Valacich Chapter 13 Finalizing Design Specifications

Learning Objectives Discuss how the need for system design specifications varies by system development methodology. Define quality requirements and write quality requirement statements. Read and understand a structure chart. Explain the roles of prototyping and CASE tools in capturing design specifications. Chapter 13 © 2008 by Prentice Hall

Finalizing Design Specifications Chapter 13 © 2008 by Prentice Hall

The Process of Finalizing Design Specifications Less costly to correct and detect errors during the design phase. Take logical design information and turn it into a blueprint for the physical information system. Can be paper-based or computer-based. Can be written, graphical, or combination of the two. Can be high-level broad-based or detailed as possible. Format and amount of detail will be driven by intended audience. Good specifications should be stated simply, completely, unambiguous, and have attributes that make requirements more understandable. Chapter 13 © 2008 by Prentice Hall

Design Specification Documents Contains: Overall system description. Interface requirements. System features. Nonfunctional requirements. Other requirements. Supporting diagrams and models (e.g., structure chart). Chapter 13 © 2008 by Prentice Hall

Structure Chart Structure Chart: a hierarchical diagram that shows how an information system is organized. Shows how an information system is organized in hierarchical models. Shows how parts of a system are related to one another. Shows breakdown of a system into programs and internal structures of programs written in third- and fourth-generation languages. Chapter 13 © 2008 by Prentice Hall

Structure Chart (Cont.) Structure chart is composed of modules. Modules: a self-contained component of a system that is defined by its function. Functions or subroutines in the resulting computer program (COBOL, BASIC, FORTRAN). Method in object-oriented language. Chapter 13 © 2008 by Prentice Hall

Structure Chart (Cont.) Pseudocode: a method for representing the instructions in a module with language very similar to computer programming code. Serves two functions: Helps analyst think in a structured way about the task a module is designed to perform. Acts as a communication tool between analyst and programmer. Chapter 13 © 2008 by Prentice Hall

Roles of prototyping in capturing design specifications

Evolutionary Prototyping Begin by modeling parts of the target system. If successful, evolve remaining system from prototype. Prototype becomes actual production system. Often, difficult parts of the system are prototyped first. Exception handling must be added to prototype. Chapter 13 © 2008 by Prentice Hall

Throwaway Prototyping Prototype is not preserved. It is developed quickly to demonstrate unclear aspect of system design. CASE tools aid this approach. Chapter 13 © 2008 by Prentice Hall

Summary In this chapter you learned how to: Discuss how the need for system design specifications varies by system development methodology. Define quality requirements and write quality requirement statements. Read and understand a structure chart. Explain the roles of prototyping in capturing design specifications. Chapter 13 © 2008 by Prentice Hall