Structured approach and object-oriented approach

Structured approach and object-oriented approach

14231011 Gold Ho

Directory

I. Structured approach

1. Characteristics of structured methods
2. The development of structured methods

Ii. Object-oriented approach

1. The characteristics of object-oriented methods
2. The development of object-oriented method

Third, Comparison

1. Difference
2. Application Status

Iv. Summary and Prospect

V. References

Background:

A variety of software development methods are accompanied by the 60 's "software Crisis" produced. In order to deal with the various difficulties encountered in the development of large-scale software, people have created various methods to guide the development of software. These methods can be broadly divided into three categories: structured methods, object-oriented methods and formal methods. In the past more than 30 years, people have done a lot of work on the research and application of structured method and object-oriented method. The structure method is the most mature and the most influential. Until now, 60% to 70% of systems have been developed using a structured approach. The object-oriented approach has developed rapidly over the past ten years, and it has a tendency to replace the structured method. "2" below will be introduced by the two main mainstream development methods, compare their differences and research status, and future development to make a prospect.

I. Structured approach

A) characteristics of the structured approach "2"

Structured method is based on functional decomposition design system structure, it simulates the objective world from the internal function. The main tool used is the dataflow diagram DFD. Simplify the problem by continually decomposing the complex processing of the DFD into a sub-flow diagram.

Advantage: The structure method can increase the readability of software specification and the reliability of software system. The flow chart is easy to understand and facilitates the communication between developers and customers.

Disadvantage: The software system structure is very sensitive to the change of function, and the function change often means redesign. The design of software is difficult to reuse, delaying the development process.

b) Development of a structured approach

In 1966, C-bohm and G-jacopini put forward the theory of "program Structure", and gave the proof that the logical structure of any program can be expressed by sequential structure, selection structure and cyclic structure. On the basis of the program structure theory, in 1968, Dykstra put forward the problem of "GOTO statement is harmful", and aroused the general attention, the SP formed gradually, and became an important method in the field of computer software, which is of great significance to the development of computer software. With the formation of SP, Modula-2, C and Ada have appeared in the structure of programming language. "1"

Ii. Object-oriented approach

A) The characteristics of the object-oriented approach "2"

The object-oriented approach simulates the objective world from the internal structure. The object here is the direct image of the objective world object. Objects contain not only data, but also methods for manipulating data. Communication between objects is done by sending a message.

Advantages: Because of the concept of inheritance, it is advantageous to the reuse of software. Judging from the stability of the model, it is also higher than the structural method.

Disadvantage: The developed software redundancy part is many, from the efficiency aspect, is lower than the structure method; And because of its encapsulation, so that the internal control of the system is not clear, to the future maintenance work to increase the difficulty.

b) Development of object-oriented approaches

The object-oriented approach originates from the object-oriented programming language (Obiect oriented program Ianguage, referred to as OOPL). The object-oriented programming language began in the late the 1960s and the first OOPL was the Simula language developed by the Norwegian Computing Center Kristennygaard and Ole-johan Dahl in 1967, which introduced many object-oriented concepts such as class and inheritance. Influenced by the Simula language, in 1972, Alan Kay successfully developed the Smalltalk language in Xerox and made a more precise definition of some object-oriented concepts. In 1980, Xerox launched the Smalltalk-80 language marking the 00PL into the practical phase. In the the 1980s, OOPL was greatly developed, and a large number of practical object-oriented languages appeared in succession. "1"

Third, Comparison

A) difference between "3"

According to the Reading literature, the author thinks that the biggest difference between the structure method and the object-oriented method is that the structured method focuses on the characterization of the system function, while the object-oriented method is data-centric. From this essential difference, it leads to their respective characteristics.

The first concern of the structured method is the function, emphasizing the module (i.e. process) as the center, adopting the modular, top-down, step-up design process, the system is a set of functions and processes to realize the function of the module, the structure is clear, the readability is good, is indeed an effective means to improve the quality of software development. Each module is likely to maintain a strong independence, but it is often independent of the database structure, the function module and the database is not mapped between the logical mode, the program and data structure is difficult to encapsulate together. If the functionality of the problem world is more complex or more important than data, then the structured approach should still be the preferred method. If the data structure is complex, the module independence is difficult to guarantee.

The object-oriented method starts from the processed data, describes the system with the data as the center, and the data is more stable than the function, so the system model can map the problem domain model well. The application of object, class, inheritance, polymorphism, dynamic concept and facility, obviously makes the object-oriented design method have some advantages, and can provide an effective way to produce reusable software components and solve the complexity problem of software.

b) Application Status

Currently, 60% to 70% of systems are developed using a structured approach. The object-oriented approach has developed rapidly over the past ten years, and it has a tendency to replace the structured method. However, in the search for information, it was found that many of the research in the software development, the use of the two methods of their respective advantages, in large systems to integrate the two methods. "1"

Iv. Summary and Prospect

The above system introduces the characteristics of the structure method and the object-oriented method. The emphasis is on comparing their differences and analyzing their pros and cons. The author thinks: Facing more and more complex software development, more and more data, object-oriented will occupy the subject position in the program design. This improves the encapsulation of the data, enhances the reuse of the code, and models the real world at a higher level.

In addition to the two development methods mentioned above, there is a software development approach called formal approach, although not under this topic, but the feeling of the future may also become a very high reliability demand for the development of software development methods. Individuals also prefer this formalized development approach, which can be proven and not only validated by testing. This development method, in a variety of control, management system, for the software reliability requirements of the field is very high, will be very good application.

V. References

"1" Software development method ——— structured method compared with object-oriented method, Wang Hanhao Sega Shang, Science & Technology Information 2011 13th

"2" the Comparison and combination of structured methodology,

object-oriented methodology and formal Methods,miu Huaikou, Gao xiaolei and Li gang,computer engin EERING& Science Vo L.. 4, 1999

Comparison of structured method and object-oriented method in "3" Software engineering, Horondan, Journalof INNER Mongolia RADIO &tv UNIVERSITY No.2, (Sum No. 90) 2nd issue 2007 (total 90th period)

Structured approach and object-oriented approach