第二章结构化建模与工具

ProcessAnalyst Model Basics
Objects in a PAM:
• Data item:Elementary piece of information • External entity:Active object which transmits or receives data from the system • Process:Data transformation • Data flow:Transfer of data between processes, external entities, and data stores • Data store:Place where data in the model is stored
– Standard parameters:Common data controls (minimum, maximum, and accepted values). – Validation rules:Customized rules for data validation.
Processes
Business Rules
Types of business rules • Definition:Characteristics or properties of an object in the information system. e.g: A customer is a person identified by a name and an address. • Fact:Certainty or an existence in the information system. e.g: A client may place one or more orders.
ProcessAnalyst Model Basics
A PAM enables you to:
• Analyze the processes of a system • Represent these processes in the form of a model • Create a hierarchical tree structure representing these processes
Applying business rules to objects
• You can apply a business rule to existing objects.
Domains and data items
What is a Domain?
• Domain help you identify the types of
2.1.1 结构化方法概述
• 软件工程方法的主要概念和技术： 自顶向下的设计方法 结构化程序设计 模块化 逐步求精和功能分解 软件质量度量 程序设计语言的抽象 • 主要步骤 • 代表性的结构化方法 DeMarco方法、Yourdon方法、Jacson方法、 Martin信息工程方法等。
软件工程方法程序开发步骤
Domains and data items
What is a data item ?
• A data item is an elementary piece of information in the data dictionary. Rather than creating an attribute directly attached to an object, you can define a data item first and then attach it to an object. • You can add data items to data stores and to data flows using the data store and data flow property sheets.
Domains and data items
check parameters
• Check parameters indicate data ranges and validation rules. You can attach check parameters to domains and data items. • There are two types of check parameters:
2.2 PowerDesigner建模
– PowerDesigner是Sybase公司推出的一组结构 化模型设计工具。由六个工具集成： – ProcessAnalyst:用于系统分析。 – DataArchitect:用于数据库建模。 – Appmodeler:用于应用对象和数据敏感组件 的生成。 – WarehouseArchitect:用于数据仓库建模。 – Viewer:用于以只读的方式访问模型。
information in your project. Applying domains to data items makes it easier to standardize data characteristics. • In a PAM, you can associate the following information with a domain: – Data type, length, and precision – Check parameters – Business rules
Business Rules
Types of business rules
• Formula:Calculation employed in the information system. e.g: The total order is the sum of all the order line costs. • Validation:Constraint on a value in the information system. e.g:The sum of the order totals for a given client must not be greater than that client‘s allowance.
Business ቤተ መጻሕፍቲ ባይዱules
What is a business rule?
• A business rule is a rule that your business follows. • A business rule could be a government-imposed law, a customer requirement, or an internal guidelin • Business rules guide and document the creation of a model. • business rules complement model graphics with information that is not easily represented graphically • Expressions remind you to create validation rules if you use the PAM as a basis for creating a CDM
What is a process ?
• A process represents a transformation of data. For example, in a model about the publication of books, selecting a manuscript is a process.
2.1.5 Martin信息工程方法 • 分析步骤：
1.规划信息策略：企业的全局模型及其数据。 2.应用领域分析：定义具体业务领域的实体及其 关系。 3.系统设计：程序结构、数据结构、动作图、屏 幕/报告格式等。 4.构造：物理设计和程序实现。
• 表达工具：
实体关系图、数据依赖图、动作图等。
第二章 结构化建模与工具
All methodologies implemented in ProcessAnalyst use the same data processing concepts:
• Process:"Black box" which receives data, transforms it, and produces a result. • Process decomposition:Breakdown of the process into several lower hierarchical levels. • External entity:Source of data used in the model • Data store:Location where data is temporarily or permanently stored in the system • Data flow:Transfer of data between the various components of the system
1.数据步：画出所有输入、输出数据流的网络图， 再表示为分层结构。 2.程序步：把数据结构组合成一个程序结构。 （通过识别数据结构模块间的消费－生产者关 系） 3.操作步：列出将输入变成输出的操作，安排在 程序结构中的合适地方。 4.正文步：用伪码描述的程序设计。
• 表达工具：
系统网络图、树型结构图、结构化正文（伪码）
ProcessAnalyst Model Basics
What is a PAM?
• PAM:Process Analyst Model. • ProcessAnalyst is a PowerDesigner tool which enables you to represent the processes in your information system. • A PAM shows how data is transformed and shows the functional processes applied to the data.
Methodology
ProcessAnalyst supports four methods:
• Object Modeling Technique (OMT) functional model • Yourdon/DeMarco • Gane & Sarson • Structured System Analysis and Design Methodology (SSADM)
2.2.1 ProcessAnalyst
• ProcessAnalyst Model Basics
• • • • • • • • Methodology Business Rules Domains and data items Processes Global and local objects Checking a PAM CRUD matrix & Report Example
2.1.2 DeMarco结构化分析方法 • 分析步骤： 1.描述当前系统的物理模型 2.抽象当前系统的逻辑模型 3.设计目标系统的逻辑模型 4.建立目标系统的物理模型（可多个） 5.估算物理模型的成本和进度 6.选择一个物理模型作为目标系统的需求 7.将结构化规格说明组装：DFD+DD+小说 明
Demacro方法步骤
2.1.3Yourdon 结构化设计 • 设计步骤： 1.划出数据流图 2.划出程序结构图（变化分析和事务分析） 3.评估设计（耦合性、内聚性度量） 4.实现设计（物理程序设计） • 使用的表示工具 DFD、MSD、IPO图、模块说明
2.1.4 Jackson程序设计方法 • 设计步骤：