Software Engineering-Requirement Analysis

Software Requirement analysis is the focus of the entire software project. Only by deeply understanding what we need to do can we better design what we do and how we do it ".

 

Requirement Analysis:The Study Targets users' requirements for software projects. The requirements of users must be fully understood and the requirements of accepted users must be expressed. Is the basis of software design.

 

Click to view the big chart:

 

When drawing a data flow diagram, you must consider the following:

Principles for checking and modifying a data flow chart:

1. All graphical symbols are limited to the preceding four basic graphic elements.
2. The main chart must contain the preceding four basic elements.

1. Each processing process must have at least one input data stream and one output data stream.
2. Data Streams on the master image must be enclosed in external entities.

1. Number the processing box by layer. Number indicates the level of the processing and parent-child relationship of the upper and lower layers

1. It is required that a data stream subgraph must correspond to a processing operation on the previous layer, and the input and output data streams of the two must be consistent.

1. Some material flows can be added to help users understand

 

Note:

1. Each element must have a name (including data streams)
2. Control flow is not supported in data flow charts.
3. Tedious details can be ignored during initial painting to focus on the main data streams

Step: determine the main processing-determine the source point-further division

The flow direction can be:

Processing-processing

Processing-File

Processing-source point

File-processing

Source point-processing

It cannot be:

File-file,

File-source point

In general:

Data streams are either from processing or from streaming processing.

 

The main document formed in the demand analysis stage is the requirement specification ".

Requirement specification requirements:

1. Consistency
2. Integrity

1. Reality

1. Validity

1. Verifiable

 

Principles of requirement specifications:

1. If you only implement a small project of a large project, you should describe the large project in the specification.
2. Separates functions from reality, that is, to describe what to do rather than how to implement it"
3. Processing-oriented specification language (or system definition language) is required)