On structured and object-oriented methods

On structured and object-oriented methods

 

2. Structured Software Development Method

Structured Software development is a kind of traditional software development method in the early stage. Its basic idea is to break down and Abstract Software Based on functions to form a systematic module structure, in this way, the structural design and structured programming of each module are carried out to complete the development of the entire system. The whole method is to break down a complex system into a slightly simple module for processing, so as to simplify the complicated problem and complete the development work efficiently.

The Structured Software development method consists of three parts: structural analysis, structural design, and structural program design.

Structured Analysis is a data stream-oriented system analysis method. We can analyze data streams in detail through data flow charts, data dictionaries, decision tables, decision trees, or object relational graphs. A common analysis method is data flow diagram and object relationship diagram. The former establishes a system logic model through system hierarchy, while the latter is the basis of backend database design. Let's take a data flow chart as an example. The core idea of a data flow chart is to layer and gradually reflect the logic functions of the system through layers. The overall idea is to first determine the data stream between the system and the external entities involved in the system, and then analyze the main functions of the system on this basis, so as to abstract the processing module of the system and realize data stream layering.

Structured design is also an important part of the structural method. Based on structural analysis, It maps the analysis model to the design model to obtain the module structure and database structure of the system. In fact, the module structure of the system is obtained based on the data flow diagram and corresponding Transformation Analysis and transaction analysis. When the ing process only involves transformation analysis and does not involve transaction analysis, the designed module must meet the requirements of high independence.

After the structural design stage, it is the structural program design stage. The objectives of this stage are relatively clear, that is, the corresponding code is implemented according to the structure of each Designed module, by analyzing the internal logic structure of each module, the code framework and internal implementation of each module are designed, which is the least abstract stage in the three phases.

3. Object-Oriented Software Development Method

The development of object-oriented development methods is closely related to the emergence of some object-oriented languages (such as C ++ and Java). In the current software industry, more and more people are using Java, PHP, C # and other languages for development. This shows that object-oriented development methods have occupied most fields of software development, object-oriented modeling is fundamental.

Like structured development, object-oriented analysis, object-oriented design, and object-oriented programming are divided into three parts. In the object-oriented method, UML is a very important part. It covers all aspects from Object-Oriented Analysis to design to program design, through UML modeling, You can systematically analyze the overall model of the system involved and the design of each module. In fact, the object-oriented thinking is to abstract people, things, and things that exist in reality into one class after another, and complete various functions through the interaction of attributes and methods, the process of establishing this model integrates analysis and design, and good encapsulation reduces the difficulty of coding and improves the quality of software development from thought to implementation.

Iv. Comparison between structured and object-oriented

Both structured and object-oriented methods are classic development methods. It is hard to say which method is better. You can only say which method is more suitable for development. This is called the right remedy ".

Structured methods are based on functional decomposition and abstraction. Therefore, the model is simple, intuitive, and readable, it can break down a large and complex system into multiple independent small modules to facilitate communication between customers and developers, and effectively improve the quality of software development. On the other hand, considering the particularity of the computer industry and software engineering, the rapid upgrading and flexibility are the characteristics of the entire industry. Therefore, changes in demand are inevitable. However, the underlying module is greatly affected by frequent demand changes. A small demand change may cause a huge reconstruction of the entire system from the underlying layer. Therefore, the structured method is weak in the maintenance layer and will be constantly in the cycle of demand changes-> re-structured analysis-> modify module-> Software reconstruction-> demand changes.

The object-oriented method is mainly based on the interaction between objects and is a data-centric system. The data has better stability than the functions. Therefore, the object-oriented method can naturally face the changes in requirements and can easily perform system maintenance and code reuse. The disadvantages of the object-oriented method are also obvious, that is, it is not applicable to the development of some large systems, because the large scale of large systems, if there is no clear module division during the development process, the system structure division will be unreasonable and the model establishment will be too complicated. In addition, it is very difficult for the customer to understand the modeling conditions in UML and the relationship between classes in the class diagram. This increases the difficulty for developers to communicate with the customer to a certain extent, development is not a good phenomenon.

The following table shows the differences between the two development methods:

	Structured Method	Object-oriented Method
Execution efficiency	The generated executable code is direct and efficient, and the system runs efficiently.	The generated executable code is complex, and the execution efficiency of large systems is low.
Reusability	It is difficult to modify and expand. When the external interface of the system changes, the system structure will be greatly changed.	When data and operations are combined, code can be reused through inheritance, abstraction, and other mechanisms when similar problems are encountered.
Compilation process	The code generated by the structured method is directly compiled and run.	The code generated by the object-oriented method must be compiled into structured code by the compiler before further running.
Difficulty	The structured method is simple and easy to understand.	The object-oriented method covers a wide range of content and involves many aspects. It often requires a supported analysis and design method.
Application Scope	It is applicable to the problem of few data but many operations, such as a function-based system like the operating system.	Applicable to systems with data-based operations, such as databases or data management systems.

 

V. Combination of structuring and object-oriented

We can intuitively understand structured methods and object-oriented methods, and find that structured methods are process-oriented, which is closer to objective implementation of requirements on the computer physical layer; the object-oriented method is more in line with people's habits. Therefore, in the actual development process, we can combine the two and adopt a comprehensive programming method, such as using structured analysis and design methods in the analysis and design stages, further generate the software structure. Then, you can use some conversion methods to obtain the controls required for Object-Oriented coding. Finally, you can use the object-oriented coding method to design the entire program. This not only saves time in the analysis and design of structured methods, reduces errors, simplifies problems, but also ensures high interaction and reusability of program design, in addition, the adaptability of the software has been greatly improved to achieve a win-win effect.

 

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On structured and object-oriented methods