【正文】 lder that is not the primary actor but receives something of value from the use case. – . the warehouse receiving a packing slip Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Use Case Extends Relationship ? Extension use case（擴展用例） – a use case consisting of steps extracted from a more plex use case in order to simplify the original case and thus extend its functionality. – Relationship between the extension use case and the use case it is extending is called an extends relationship. – Represented as an arrowheaded line beginning at the extension use case and point to the use case it is extending. – Each extends relationship line is labeled “extends.” Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Use Case Depends On Relationship Depends On – a use case relationship that specifies which other use cases must be performed before the current use case. – Can help determine sequence in which use cases need to be developed. – Depicted as an arrow headed line beginning at one use case and pointing to a use case it is dependent on. – Each depends on relationship line is labeled “depends on.” Copyright 169。 2022 The McGrawHill Companies. All Rights reserved The Process of Requirements UseCase Modeling ? Steps步驟 1. Identify business actors (參與者 ). 2. Identify business use cases (用例 ). 3. Construct usecase model diagram (用例模型圖 ). 4. Documents business requirements usecase narratives (用例說明 ). Copyright 169。 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Step 1: identify Business Actors ? When looking for actors, ask the following questions: – Who or what provides inputs to the system? 誰向系統(tǒng)提供輸入？ – Who or what receives outputs from the system? 誰接收系統(tǒng)的輸出？ – Are interfaces (接口 ) required to other systems? 需要與其他系統(tǒng)接口嗎？ – Are there events that are automatically triggered (觸發(fā) ) at a predetermined time? 有無在預(yù)定時間自動觸發(fā)的事件？ – Who will maintain information in the system? 誰來維護系統(tǒng)中的信息？ Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Step 2: Identify Business Requirements Use Cases ? During requirements analysis, strive（ 努力） to identify and document (記錄 ) only the most critical, plex, and important use cases, often called essential use cases. 在需求分析階段，應(yīng)重點識別和記錄那些最為關(guān)鍵、最為復(fù)雜、以及最為重要的用例，統(tǒng)稱為基本用例 Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample Context Diagram Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample UseCase Glossary (continued) continued Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Step 3: Construct UseCase Model Diagram Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample HighLevel Version of a UseCase Narrative Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample Expanded Version of a UseCase Narrative (cont) continued Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Use Cases and Project Management ? Usecase model can drive the entire development effort. ? Project manager or systems analyst uses business requirements use cases to plan (estimate and schedule) the build cycles of the project. – Build cycles are scoped on the basis of the importance of the use case and the time it takes to implement the use case. ? To determine importance of the use cases, will create: – Usecase ranking and evaluation matrix – Usecase dependency diagram Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample UseCase Ranking and Priority Matrix Copyright 169。 2022 The McGrawHill Companies. All Rights reserved Sample UseCase Dependency Diagram Copyright 169。 要求分析該系統(tǒng)，并 給出該系統(tǒng)的用例圖。 2022 The McGrawHill Companies. All Rights reserved 練習(xí) 1（續(xù)） ? 如果該小型圖書館完全采用不記名押金管理體系，則用例圖應(yīng)做何改動？