Software Engineering 2007/2008 Chapter 2 Modeling the Process and Life Cycle

Learning objectives  Define what is meant by the term “ process ” and how it applies to software development. ( 过程的定义与其在软件开发中的应用 )   Describe the activities, resources and products involved in the software development process. （软件开发过程中有关活动、资源与产品的描述）   Describe several different models of the software development process and understand their drawbacks and when they are applicable. （描述了几个不同的软件开发过程模型，了解它们的缺点与适用 条件）   Describe the characteristics of several different tools and techniques for process modeling. （描述了过程模型中几个不同的工具与方法的特征）

2.1 THE MEANING OF PROCESS （过程的含义） ① A process A series of steps involving activities( 活跃 ), constraints( 约束 ), and resources( 资源 ) that produce an intended( 打算 / 计划 ) output of some kind.

2.1 THE MEANING OF PROCESS ② process characteristics. The process prescribes( 规定 ) all of the major process activities.. The process uses resources subject to a set of constraints (such as a schedule), and produces intermediate( 中间的 ) and final products.. The process may be composed( 组成，构成 ) of subprocesses that are linked in some way. The process may be defined as a hierarchy( 层次 ) of processes, organized so that each sub- process has its own process model.. Each process activity has entry and exit criteria( 准则，条 件 ), so that we know when the activity begins and ends.

2.1 THE MEANING OF PROCESS ② process characteristics. The activities are organized in a sequence( 顺序，时序 ), so that it is dear when one activity is performed relative to the other activities.. Every process has a set of guiding( 导向 ) principles that explain the goals of each activity. Constraints( 约束条件 ) or controls may apply to an activity resource, or product. For example, the budget or schedule may constrain the length of time an activity may take or a tool may limit the way in which a resource may be used.

2.1 THE MEANING OF PROCESS ③ software life Cycle it describes the life of a software product from its conception( 构思 ) to its implementation( 实现 ), delivery( 交付 ), use( 应用 ), and maintenance( 维护 )

2.2 SOFTWARE PROCESS MODELS （软件过程模型）  Waterfall Model （瀑布模型） Requirements Analysis System Design Program Design Coding Unit & Integration Testing System Testing Acceptance Testing Operation & Maintenance

2.2 SOFTWARE PROCESS MODELS The waterfall model with prototyping Verify Requirements Analysis System Design Program Design Coding Unit & Inte- gration Testing System Testing Acceptance Testing Operation & Maintenance Prototyping Validate

2.2 SOFTWARE PROCESS MODELS  V Model （ V 模型） The V model is a variation( 变种 ) of the waterfall model that demonstrates( 示范 ) how the testing activities are related to analysis and design Requirements Analysis System Design Program Design Coding Unit & Inte- gration Testing System Testing Acceptance Testing Operation & Maintenance

2.2 SOFTWARE PROCESS MODELS  Prototyping Model （原型模型） revise prototype user/ customer review List of Revisions ( 修正 ) List of Revisions List of Revisions Prototype Requirements Prototype Design Prototype System Test System Requirements (sometimes informal or incomplete) Delivered System The prototyping model

2.2 SOFTWARE PROCESS MODELS  Operational Specification （操作规范） Execute( 执行 ) and Revise Operational Specification (problem-oriented) Transformed Specification (implementation ( 实施 )-oriented) Test System Requirements (sometimes informal or incomplete) Delivered System The operational specification model

2.2 SOFTWARE PROCESS MODELS  Transformational Model （转换模型） Sequence of transformation plus rationale for them Compare with requirements; update as needed Formal Specification Transform N · Test System Requirements (sometimes informal or incomplete) Delivered System The transformational model. Transform 2 Transform 1 Formal Development Record

2.2 SOFTWARE PROCESS MODELS  Phased Development: Increments and Interactions( 分 阶段开发：增量交互 )

2.2 SOFTWARE PROCESS MODELS  Spiral Model （螺旋模型）

2.3 TOOLS AND TECHNIQUES FOR PROCESS MODELING （过程模型的工具与方法） In particular, the elements( 原理 ) of a process are viewed in terms of seven types: 1. Activity: Something that will happen in a process. This element can be related to what happens before and after, what resources are needed, What triggers the activity's start, what rules govern the activity, how to describe the algorithms( 运算法则 ) and lessons learned, and how to relate the activity to the project team. 2. Sequence( 顺序 ): The order of activities. The sequence can be described using triggers( 触发器 ), programming constructs, transformations, ordering, or satisfaction of conditions. 3. Process model: A view of interest about the system. Thus, parts of the process may be represented as a separate model, either to predict( 预计，预言，预测 ) process behavior or to examine certain characteristics. To be continue ….

2.3 TOOLS AND TECHNIQUES FOR PROCESS MODELING 4. Resource: A necessary item ( 项目；条款，内容 ; 对象，数 据项 ), tool, or person. Resources can include equipment, time, office space, people, techniques, and so on. The process model identifies how much of each resource is needed for each activity 5. Control: An external influence ( 外部影响 ) over process enactment( 设定, 制定 ). The controls may be manual or automatic, human or mechanical. 6. Policy( 政策 ): A guiding principle ( 指导原则 ). This high- level process constraint influences process enactment. It may include a prescribed development process, a tool that must be used, or a mandatory management style. 7. Organization: The hierarchical structure ( 层次结构, 分级 结构 ) of process agents( 代理 ( 商 )), with physical grouping corresponding to logical grouping and related roles.

2.3 TOOLS AND TECHNIQUES FOR PROCESS MODELING  Dynamic Modeling: System Dynamics （动态模型：系统动态） Structure of software development (Abdel-Hamid l996).

2.4 PRACTICAL PROCESS MODELING （实际的过程模型）  Marvel Case Studies 1. a rule-based specification of process behavior ( 一个基于规则的过程行为 ) 2. an object-oriented definition of the model's information process( 一个面向对象模型的信息过 程的定义 ) 3. a set of envelopes to interface between Marvel and external software tools used to execute the process.

2.4 PRACTICAL PROCESS MODELING  Desirable properties of Process Modeling Tools and Techniques （合乎过程模型要求的工具与方法的性质） 1. Facilitates human understanding and communication. ( 易于理解与交流 ) 2. Supports process improvement. ( 支持过程的改进 ) 3. Supports process management. ( 支持过程管理 ) 4. Provides automated guidance in performing the process. ( 在执行过程中自动给予指导 ) 5. Supports automated process execution. ( 支持 自动过程的运行 )