tailieunhanh - Lecture Software requirements engineering - Lecture­ 15: Elaboration process

After this chapter the student should have acquired the following knowledge and skills: Object oriented analysis, behavioral modeling, structure analysis, flow oriented modeling, flow-oriented modeling, data flow diagrams (DFD), decomposition and abstraction, the procedure for constructing DFD’s,. | Elaboration Process Lecture-15 Recap Object Oriented Analysis Behavioral Modeling Today’s lecture Structure analysis Flow oriented modeling Flow-Oriented Modeling 4 What is a Data Flow Diagram? Known as DFDs A way to model a real world situation They are the interface between the real world activities and an understanding of how this can be converted into a computer system. Why do we use DFDs? It is a way of taking the physical view and converting it into a logical view. The physical view - all documents involved The logical view - the data they contain Their main purpose is to communicate with the user, the analyst’s understanding of the scope of the required system Where do they fit in? Analysis (What do we do?) Fact finding investigate business process and the current system modelling the current and required systems deliverables - requirements specification logical models of the required system Life Cycle Phases Planning Feasibility Study Analysis Design Code and Unit test Data . | Elaboration Process Lecture-15 Recap Object Oriented Analysis Behavioral Modeling Today’s lecture Structure analysis Flow oriented modeling Flow-Oriented Modeling 4 What is a Data Flow Diagram? Known as DFDs A way to model a real world situation They are the interface between the real world activities and an understanding of how this can be converted into a computer system. Why do we use DFDs? It is a way of taking the physical view and converting it into a logical view. The physical view - all documents involved The logical view - the data they contain Their main purpose is to communicate with the user, the analyst’s understanding of the scope of the required system Where do they fit in? Analysis (What do we do?) Fact finding investigate business process and the current system modelling the current and required systems deliverables - requirements specification logical models of the required system Life Cycle Phases Planning Feasibility Study Analysis Design Code and Unit test Data Flow Diagrams (DFD) DFDs describe the flow of data or information into and out of a system what does the system do to the data? A DFD is a graphic representation of the flow of data or information through a system 8 3 BCS - GP1 Use example of borrow library book here to illustrate the different components. Student is external passes in request (book and student details) into validate student process output valid student request into reserve book process. Two data stores, students and loans. Output back to student is book; Case study - Just A Line system Decomposition and Abstraction Decomposition - Divide and subdivide into manageable size problems Abstraction - Concentrate on the important issues and ignore the irrelevant 4 Main Elements external entity - people or organisations that send data into the system or receive data from the system process - models what happens to the data . transforms incoming data into outgoing data data store - represents permanent data that is used by .