Software Engineering-Requirement Analysis Method

Source: Internet
Author: User

Structural Analysis (SA method)

Structural Analysis Methods break down and abstract points of view. Any information processing process is regarded as a device that transforms the input data into the required output information. Therefore, data stream analysis is the starting point of demand analysis. the SA method uses the "top-down, out-of-the-box, and gradually refine" strategy to analyze the problem. the practice is to first regard the entire system as a processing (black box), and identify the system boundary and all input/output data streams. then, the process is further divided into several simple functions, including complex functions and detailed descriptions. the main methods to describe the SA structure are Data Flow Graphs and data dictionaries.

Step 3:

  1. Determine the system boundary and draw the top-layer data flow diagram
  2. Top-down, internal decomposition of each processing, draw a hierarchical data flow diagram (DFD)
  3. Review the data flow chart

The guiding principles for layered DFD charts are as follows:

  1. Pay attention to the balance between the parent and subgraphs.
  2. Differentiate between local files and external items.
  3. Master the Decomposition Speed.
  1. Follow the processing numbering rules.

Because the DFD graph at the bottom layer contains all the data and processing of the system, the data at the same time indicates the output of the system, which must be clear and generally starts from the end of the data, the DFD chart traces back to the data source point step by step, which makes it easier to see the ins and outs of each data item in the data stream and helps reduce errors and omissions.

Object-Oriented Analysis Method (OOA)

Let's talk about my understanding of basic object-oriented knowledge. according to object-oriented = Object + class + inheritance + communication, an object is an abstract representation of the real world. We know that an object has attributes, events, and methods. if many objects share common attributes, they become a class. Classes are collections of similar objects with the same data and operations. an isosceles triangle is an object. Therefore, an isosceles triangle and a right triangle belong to the same type of triangle. A triangle is a class. the association between a triangle and an isosceles triangle is inheritance. inheritance is a new definition technology based on existing definitions. likewise, passenger ships are a special class of ships. when we define a passenger ship, we will say, what are the characteristics of a passenger ship. we focus on the special characteristics of the Passenger Ship Based on the ship, instead of explaining the concept of the ship.


Object-oriented features module encapsulation and internal information hiding. in object-oriented analysis, an object is an abstract representation of the real world, which enables system analysts to focus on understanding the problematic space and ultimately produce a visible, review and manageable and stable hierarchical model. objects are attributes of external entities and allowed service abstraction. the only way to access a property is through a service. attributes and their services are regarded as an inherent whole in the object-oriented analysis method. A series of objects with the same attributes and service abstraction form an object class. the object-oriented model can contain several object classes, which correspond to the abstraction at different layers of the generated model. such abstract classes have a certain level of association and property inheritance relationships.

Step 5:

  1. Identifies an object (class ).
  2. Id structure.
  3. Identifies a topic.
  4. Define attributes.
  5. Define a service.

    For author information, seeGu Haiyan's blog
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