SSADM in Practice

Frontmatter

1. Introduction to Systems Analysis and Design

Abstract

In this chapter we look at the traditional system development life cycle, identify the problems associated with it, introduce the concept of structured methods and provide a brief introduction to the Structured Systems Analysis and Design Method (SSADM).

Joyce Duncan, Lesley Rackley, Alexandria Walker

2. Stage 1: Investigation of Current Environment

Abstract

In this chapter we look in more detail at SSADM Stage 1 and introduce the technique of Data Flow Diagramming and the Requirements Catalogue (RC).

Joyce Duncan, Lesley Rackley, Alexandria Walker

3. Stage 1: Investigation of Current Environment (Continued)

Abstract

This chapter introduces two concepts which are used in Stage 1: Logical Data Modelling (LDM) and the Data Store/Entity Cross Reference.

Joyce Duncan, Lesley Rackley, Alexandria Walker

4. Completion of Stage 1 and Stage 2

Abstract

This chapter will bring together the final tasks involved in Stage 1. Many of these tasks involve completion of documentation that supports the DFD and LDM. The analyst must then define a logical system by converting the Current Physical Model to a Current Logical Model before moving into Stage 2 and the selection of Business System Options.

Joyce Duncan, Lesley Rackley, Alexandria Walker

5. Stage 3 — Requirements Specification

Abstract

In the previous chapter, we looked at Stages 1 and 2 in which the current system was analysed into its logical components and the user selected the broad approach to be adopted for the new system. Having defined what the new system is intended to achieve in outline, we can now move into Stage 3 and start to specify the requirements in more detail. The steps and products of Stage 3 are shown in Figure 5.1.

Joyce Duncan, Lesley Rackley, Alexandria Walker

6. Step 340 — Enhance Required Logical Data Model

Abstract

Relational data analysis (RDA) and Logical data modelling (LDM) are two different but complementary ways to identify and specify data requirements. LDM works from the top down, taking an overview of the data model and gradually adding more information, while RDA works from the bottom up, starting with arbitrary data groups and forming larger groups that correspond to the entities and relationships of the LDM.

Joyce Duncan, Lesley Rackley, Alexandria Walker

7. Stage 3: Develop Processing Specification

Abstract

Step 360 defines the detailed update and enquiry processing that has, thus far, only been outlined in the DFD and Function Definitions. Another major modelling technique is used to enable the analyst to acquire a more detailed understanding of the system. Entity-event modelling leads to further explorations of how the system works and completes the Logical Data Model, providing a specification of database update processing via the effect correspondence technique.

Joyce Duncan, Lesley Rackley, Alexandria Walker

8. Stage 4: Selection of Technical Systems Options

Abstract

Much of the work carried out in Stage 4 can be thought of as relating to the guidelines within project management as much as to SSADM, and thus the methods used to produce, for example, the performance objectives, may differ from project to project. In terms of SSADM there is a need for interaction with project management and other expertise to provide the information required to shape the Technical Systems Options. The main aim of this stage is to provide a firm basis for development of the system.

Joyce Duncan, Lesley Rackley, Alexandria Walker

9. Stage 5: Logical Design

Abstract

This stage adds the specific detail of processing structures that were initially defined in the Requirements Specification and to specify the Human Computer Interface (HCI) in the form of dialogues. This detailed specification should

• be non-procedural
• be implementable on a range of technical environments
• maximise the opportunity for re-use

Joyce Duncan, Lesley Rackley, Alexandria Walker

10. Stage 6: Design of the Physical System

Abstract

Stage 6 of SSADM is concerned with converting the logical design of the new system into a physical design specification. The logical design of the system, as we have seen, is a product of Stage 5 where we produce the logical Update and Enquiry Process Structures and the Dialogue Design.

Joyce Duncan, Lesley Rackley, Alexandria Walker

11. SSADM — A Critique

Abstract

SSADM has now been widely used for a number of years and some doubts have been expressed about its contribution to the successful development of information systems. In this chapter an attempt is made to review these criticisms and generally evaluate the method.

Joyce Duncan, Lesley Rackley, Alexandria Walker

Backmatter