tailieunhanh - Lecture Software engineering (7/e): Chapter 8 – Ian Sommerville

This chapter include objectives: To explain why the context of a system should be modelled as part of the re process, to describe behavioural modelling, data modelling and object modelling, to introduce some of the notations used in the Unified Modeling Language (UML), to show how CASE workbenches support system modelling. | System models Objectives To explain why the context of a system should be modelled as part of the RE process To describe behavioural modelling, data modelling and object modelling To introduce some of the notations used in the Unified Modeling Language (UML) To show how CASE workbenches support system modelling Topics covered Context models Behavioural models Data models Object models CASE workbenches System modelling System modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers. Different models present the system from different perspectives External perspective showing the system’s context or environment; Behavioural perspective showing the behaviour of the system; Structural perspective showing the system or data architecture. Model types Data processing model showing how the data is processed at different stages. Composition model showing how entities are composed of other entities. Architectural model showing . | System models Objectives To explain why the context of a system should be modelled as part of the RE process To describe behavioural modelling, data modelling and object modelling To introduce some of the notations used in the Unified Modeling Language (UML) To show how CASE workbenches support system modelling Topics covered Context models Behavioural models Data models Object models CASE workbenches System modelling System modelling helps the analyst to understand the functionality of the system and models are used to communicate with customers. Different models present the system from different perspectives External perspective showing the system’s context or environment; Behavioural perspective showing the behaviour of the system; Structural perspective showing the system or data architecture. Model types Data processing model showing how the data is processed at different stages. Composition model showing how entities are composed of other entities. Architectural model showing principal sub-systems. Classification model showing how entities have common characteristics. Stimulus/response model showing the system’s reaction to events. Context models Context models are used to illustrate the operational context of a system - they show what lies outside the system boundaries. Social and organisational concerns may affect the decision on where to position system boundaries. Architectural models show the system and its relationship with other systems. The context of an ATM system Process models Process models show the overall process and the processes that are supported by the system. Data flow models may be used to show the processes and the flow of information from one process to another. Equipment procurement process Behavioural models Behavioural models are used to describe the overall behaviour of a system. Two types of behavioural model are: Data processing models that show how data is processed as it moves through the system; State machine models that show .