A PARTS-AND-ASSEMBLY SYSTEM SPECIFICATION TECHNIQUE USING DATA FLOW DIAGRAM

Abstract

Software reusability and parts-and-assembly concept have been identified as possible to improving software design, production and quality. There is also a strong need in the industry to find an easy-to-use system specification technique to produce an adequate specification for the design of information systems. This thesis addresses the abovementioned issues for information systems by presenting a specification technique which constructs process specification using and data flow diagram and parts-and-assembly concept. This specification technique also provides a solution for creating domains for Draco approach to construction software systems [22] for information systems. Data flow diagrams is a well known tool used in structured analysis by the system analyst and parts-and-assembly concept is an easy-to-follow approach. This specification technique produces adequate specifications. Under this approach, process (assembly) is specified through data flow diagrams formed by composing data oriented generic processes (parts) from a set of data oriented generic processes constructed in this thesis. The member data oriented generic processes are specified through the attributes of these generic processes. In this technique, a representation scheme is established for representing an output entry or a group of output entries produced by a data oriented generic process. Consequently, the data flow diagram is extended to cover the control flow by represented it through the data flow represented in the representation scheme and the control structure of the generic processes. The resulting specification for the processes is data flow diagrams with the followings: i. all the primitive processes drawn from the set of data oriented generic processes ii. all the data which are retrieved, derived or sorted/merged from other data expressed in the diagrams using the representation scheme iii. a data dictionary without explicitly specifying the composition of the data stated in ii) iv. a specification of attributes for the generic processes to replace the mini-specifications (mini-specs) The adequacy of this specification technique for specifying processes in information systems is also proven in the thesis. In conjunction with our results in process specification, an user interfaces specification technique outlined from the existing techniques is also briefly presented to complete a system specification technique for information systems. The feasibility of automatic software production from the specification is an obvious consequence of this specification technique. The production can also be achieved through the corresponding parts-an-assembly concept by assembling the software parts for the corresponding parts specified, for the physical environment. This thesis is organised into ten chapters. Chapter 1 highlights some of the current research and need which are addressed by this thesis. Chapter 2 presents the data oriented process specification approach used in the system specification technique constructed in this thesis for specifying processes in information systems. A representation scheme is also presented in this chapter for specifying an output entry or a group of output entries of a data oriented generic process for its postprocesses to process. Chapter 3 describes all the data oriented generic processes constructed and their respective attributes. Chapter 4 integrates the results presented earlier with data flow diagram and data dictionary to form a parts-and-assembly specification technique for specifying data and processes in information systems. Chapter 5 proves the adequacy of this specification technique for specifying all the processes in information systems. Chapter 6 presents a heuristics procedure for specifying a process using the specification technique. Chapter 7 outlines an user interfaces specification technique from the existing techniques. As we restrict our scope of user interfaces to screen interfaces, chapter 8 presents a deduction of screen interfaces design, such that some of the screen interfaces specification can be deduced automatically. Chapter 9 presents a specification technique to integrate the process and screen interfaces specifications to form a complete system specification technique. Chapter 10 concludes the feasibility of automatic software production from specifications constructed under this technique.