UML

简答

1.Why are linear approaches not preferred for software development?

• In linear approaches, the requirements for the software system are finalized（确定） before the design phase. Once the SRS for the software is developed, the approach assumes that there will be no change in the requirements. However, this is not true for most projects. The requirements for such software evolve during the development process and, therefore, cannot be finalized in the beginning of the project. As a result, linear approaches are not preferred.
  线性方法中的需求已经被确定了，而大多数项目要求在开发过程中还要进行演变，所以线性方法不适合。

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2.What is the main advantage of the object-oriented design approach over the function-oriented design approach?

• The object-oriented design approach applies reuse engineering on classes. The object-oriented design approach supports the inheritance of attributes and operations among classes, which enables the reusability of code.
  面向对象的设计方法将重用工程应用于类。面向对象的设计方法支持类之间的属性和操作的继承，从而实现代码的可重用性。
• The function-oriented design approach is module-centric and concentrates on functions of the software. As a result, it is difficult to separate the construction of one module from the other. Reusability of the software becomes difficult as functions become complex. Another limitation of the function-oriented approach is that data is visible and accessible across the program.
  面向功能的设计以模型为中心，注重软件功能，导致难以从其他模块分离出一个模块结构。随着功能变得复杂软件的重用性变得难以实现，面向功能的方法的数据对其他应用可见，可跨应用访问。

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3.What is the difference between OOPs and OOAD?

• Although the concept behind OOAD and OOPs is similar, OOAD is an analysis and design technique used in the analysis and design phases of the SDLC. However, OOPs is a programming technique used in the coding phase of the SDLC.
  OOAD被用在分析与设计阶段，OOPS正常被用在软件开发生命周期的编码阶段

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4.What does a deployment diagram represent?

• A deployment diagram represents all the nodes required to deploy the software, such as the client and server nodes that contains the various components of the software system.
  部署关系图表示部署软件所需要的所有节点，例如包含软件系统各种组件的客户端和服务器节点
• The deployment diagram also represents the relationship among the various nodes of the system.
  也表示系统节点间的关系

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5.Which UML diagrams can you use to design the system architecture?

• You can use the component and deployment diagrams to design the system architecture.
  组件图和部署图

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6.How can use cases help increase the project quality?

• You map the use cases with the features of the software system to ensure that use cases for all the features have been identified.
  用例与软件系统特性对应，保证所有特性都被用例确定
• Similarly, the code that is generated in the implementation phase is mapped with the use cases to verify that the code implements the functions of all the use cases.实现阶段生成的代码与用例对应，保证实现所有用例的功能

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7.What is a use case driven model?

• In a use case driven model(用例驱动模型), use cases are used throughout the Software Development Life Cycle (SDLC). You model requirements by using use cases, and then create class diagrams using the use cases identified in the requirements analysis phase. （使用在需求分析阶段定义的用例去创造类图）You also use the use cases to generate the test cases in the testing phase of the SDLC. （你也需要在软件开发的生命周期去使用用例去生成测试用例）Finally, you use the use cases for requirement traceability.
  在用例驱动模型里面，用例可以被应用于整个软件开发周期。使用用例对需求建模，然后使用在需求分析阶段被确定的用例来创建类关系图，在测试阶段使用用例来生成测试用例，使用用例进行需求跟踪。

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8.What is use case realization?

• Use case realization is a collaboration of classes that interact with each other to realize a use case. Use case realization describes how the functions of a particular use case are implemented in the design model.
  用例实现是相互交互以实现用例的类的协作。描述了在设计阶段特定用例的功能是如何实现的。

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9. How is a class diagram different from an object diagram?

• A class diagram represents classes, their attributes, operations, and relationships. Conversely, an object diagram represents objects, their attribute values, and relationships. An object in a class diagram is an instance of a class in a class diagram.
  类关系图表示类，类的属性、操作和关系。对象关系图表示对象，对象属性值和关系。对象图中的对象是类图中类的实例

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10.What is the difference between aggregation and composition?

• An aggregation relationship between two classes indicates that a class is a part of another class. Conversely, in a composition relationship, one class contains another class. For example, in an order management system, a customer can place multiple orders. Therefore, the Customer and Order classes share an aggregation relationship. Every order consists of the order information. Therefore, the Order and OrderDetail classes share a composition relationship.
  聚合：类a是类b的一部分，并且类a可独立存在。组合：类a包含类b，且类a控制类b的生命周期

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11.What is the difference between a sequence diagram and a communication diagram?

• Sequence diagram and communication diagram are the two most commonly used types of interaction diagrams. The difference between sequence and communication diagrams is that sequence diagrams depict the flow of control of messages by time ordering as opposed to communication diagrams that emphasize on the organization of objects to depict the flow of control of messages.
  序列图按时间表示信息控制流，而通信图着重表示信息对象的结构化组织。

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12.What does an activity diagram illustrate(说明)？

• An activity diagram shows the workflow or an operation in terms of the sequence of activities and transitions.
  活动图根据活动和转换顺序显示工作流程或操作。