chap7需求分析-用例圖-展示頁
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【正文】 ng above, below, or inside the ellipse. ? Actor （參與者） – anything that needs to interact with the system to exchange information. – Could be a human, an anization, another information system, an external device, or even time. ? Temporal event (時(shí)間事件 )– a system event triggered by time. – The actor is time. Copyright 169。 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Benefits of UseCase Modeling ? Provides a tool for capturing functional requirements(獲取功能需求 ). ? Provides a means of municating with users and other stakeholders concerning system functionality in a language that is easily understood.（便于溝通） ? Provides a tool for requirements traceability(需求跟蹤 ). ? Provides a framework for driving the system development project. （提供一個(gè)驅(qū)動(dòng)系統(tǒng)開發(fā)項(xiàng)目的框架） Copyright 169。 2022 The McGrawHill Companies. All Rights reserved UseCase Modeling 用例建模 ? Usecase modeling – the process of modeling a system’s functions in terms of 針對系統(tǒng)功能進(jìn)行建模： – business events：有哪些業(yè)務(wù)事件？ – who initiated the events：誰發(fā)起了這些事件？ – and how the system responds to those events：系統(tǒng)將如何響應(yīng)這些事件？ Copyright 169。 2022 The McGrawHill Companies. All Rights reserved UserCentered Development and UseCase Modeling 以用戶為中心的系統(tǒng)開發(fā) 與用例建模 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved An Introduction to UseCase Modeling 簡介 ? One of the primary challenges in a system design process is the ability to elicit(提取 ) the correct and necessary system requirements from the stakeholders and specify them in a manner understandable to them so those requirements can be verified and validated. 系統(tǒng)開發(fā)過程的首要問題 是正確地提取用戶需求，并以用戶能夠理解的方式進(jìn)行表達(dá)，以便他們他們能夠核實(shí)并確認(rèn) Copyright 169。Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Chapter 7 MODELING SYSTEM REQUIREMENTS WITH USE CASES 使用用例建模系統(tǒng)需求 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved An Introduction to UseCase Modeling 簡介 ? 傳統(tǒng)的建方法： – Data and process models – Prototypes – requirement specifications ? 問題： 設(shè)計(jì)者理解而用戶不理解 – Leads to scope creep（范圍蔓延） , schedule creep （進(jìn)度蔓延） , cost overruns（成本超支） . Copyright 169。 2022 The McGrawHill Companies. All Rights reserved UserCentered Development ? Usercentered development – a process of systems development based on understanding the needs of the stakeholders and the reasons why the system should be developed. 系統(tǒng)開發(fā)建立應(yīng)在理解用戶需求之上 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample UseCase Model Diagram Copyright 169。 2022 The McGrawHill Companies. All Rights reserved System Concepts for UseCase Modeling ? Usecase diagram – describes who will use the system and in what ways the user expects to interact with the system. 用例圖 ——描述系統(tǒng)與外部系統(tǒng)或用戶之間的交互圖 ? Usecase narrative – a textual description of the business event and how the user will interact with the system to acplish the task. 用例說明 ——針對用例執(zhí)行過程的文本說明 ? Use case –a behaviorally related sequence of steps (a scenario), both automated and manual, for the purpose of pleting a single business task. 用例 ——從外部使用者的角度描述系統(tǒng)功能，是一系列相關(guān)的操作步聚，共同完成單一的工作任務(wù)。 2022 The McGrawHill Companies. All Rights reserved Sample UseCase Model Diagram Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Four Types of Actors ? Primary business actor – The stakeholder that primarily benefits from the execution of the use case. – . the employee receiving the paycheck ? Primary system actor – The stakeholder that directly interfaces with the system to initiate or trigger the business or system event. – . the bank teller entering deposit information ? External server actor – The stakeholder that responds to a request from the use case. – . the credit bureau authorizing a credit card charge ? External receiver actor – The stakeho
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