Lab Manual ISM 224 System Analysis and DesignI

Lab Manual ISM 224 System Analysis and Design-I Department of Information systems Dr. Nissrein Babiker 1

LAB 1 Systems Theory and Process Concepts A System is a Process • The simplest process model of a system is based on inputs, outputs, and the system itself viewed a process. • The process symbol defines the boundary of the system. Dr. Nissrein Babiker 2

• The system is inside the boundary; the environment is outside that boundary. • The system exchanges inputs and outputs with its environment The Classis model of a system Dr. Nissrein Babiker 3

The Classis model of a system Dr. Nissrein Babiker 4

System Models Logical models show what a system ‘is’ or ‘does’. They are implementation -independent; that is, they depict the system independent of any technical implementation. As such , logical models illustrate the essence of the system. Popular synonyms include essential model, conceptual model, and business model. Dr. Nissrein Babiker 5

Physical models: show not only what a system ‘is’ or ‘does’, but also how the system is physically and technically implemented. They are implementation-dependent because they reflect technology choices, and the limitations of those technology choices. Synonyms include implementation model and technical model Dr. Nissrein Babiker 6

What is Process Modeling? Process modeling is a technique for organizing and documenting the structure and flow of data through a system’s PROCESSES and/or the logic, policies, and procedures to be implemented by a system’s PROCESSES. Process modeling originated in classical software engineering methods. A systems analysis process model consists of data flow diagrams (DFDs) Dr. Nissrein Babiker 7