FOOM: Functional and Object-Oriented Analysis and Design of Information Systems: An Integrated Methodology

INTRODUCTION Many paradigms for system analysis and design have been proposed over the years. Early approaches have advocated the functional approach. Common methodologies that support this approach are Structured System Analysis (SSA) and Structured System Design (SSD) (DeMarco, 1978; Yourdon & Constantine, 1979). SSA is based on the use of data flow diagrams (DFD), which define the functions to be performed by the system, the data stores within the system, the external entities, and the data flows that connect the above components. SSA and similar methodologies of that age emphasize the functional aspects of system analysis, neglecting somehow the structural aspect, namely that of modeling the data structure. Concurrently, Entity-Relationship (ER) became a popular model for designing the data structure, namely the database schema. SSD is based on the use of Structure Charts (SC), which describe the division of the system to program modules as well as the hierarchy of the different modules and their interfaces. Certain techniques have been proposed to create SCs from DFDs (see Yourdon & Constantine, 1979). The main difficulty of the above approach, that is, functional analysis followed by structured design, lies in the transition from DFDs to SCs. The translation is problematic because a DFD is a network structure, We propose FOOM (Functional and Object-Oriented Methodology), an integrated methodology for information systems analysis and design, which combines two essential software-engineering paradigms: the functional/data approach (or process-oriented) and the object-oriented (OO) approach. System analysis phase, where user requirements are set and defined, includes functional analysis and data modeling activities. This phase produces a hierarchy of data flow diagrams (DFD) and an initial OO schema, which can be created directly or from an entityrelationship diagram (ERD). The design phase is performed according to the OO approach, producing a complete OO schema and a behavior schema. The seamless transition from analysis to design is enabled thanks to ADISSA methodology, which facilitates the design of the menus, forms and reports classes, and the system behavior schema, from the DFDs and the application transactions. The paper introduces the motivation for the combined approach, outlines the methodology, and presents an example that demonstrates it.