1.2.1 Structured approach (process-oriented approach)
It is composed of three parts: structured analysis (Structured Analysis, SA), structured design (Structured Design, SD) and structured programming (Structured Programming; SP). Its essence is top-down, progressive refinement and Modular design.
Features: Clear development goals, phased development work, standardized documentation, and structured design methods (decomposition, aggregation, and gradual realization).
The structured method is currently the most mature and widely used engineering method. It is especially suitable for problems in the field of data processing, but it is not suitable for large-scale and complex system development.
Limitations and deficiencies: long development cycle (only hear the voice, not see the person), difficult to adapt to changes in requirements, rarely consider the data structure.
1.2.2 Object-oriented approach
The object-oriented (Object-Oriented, 00) method believes that the objective world is composed of various objects , everything is an object, and each object has its own motion law and internal state, and belongs to a certain object class. An element of the object class. Complex objects can be constructed in a certain way from various relatively simple objects, and the combination and interaction of different objects constitute a system.
Features:
(1) The 00 method is the current mainstream development method.
(2) The system constructed by OO method has better reusability .
(3) The 00 method makes the description of the system and the representation of the information model correspond to the objective entity and conform to people's thinking habits.
(4) It is beneficial to the exchange and communication between users and developers during the system development process , shortening the development cycle.
(Simultaneous reading: textbook P42 object-oriented analysis, P47 object-oriented design.)
At present, the development of some large-scale information systems is usually a combination of structured methods and OO methods. First use the structured method for top-down overall division; then, use the OO method for development from the bottom up Therefore, the structured method and the OO method are still two irreplaceable methods that are interdependent in the field of system development
1.2.3 Prototyping method
In general, a prototype refers to an original model that simulates a certain product.
Features:
(1) The prototyping method can shorten the system development cycle, reduce costs and risks, speed up, and obtain higher comprehensive development efficiency.
(2) The prototype method develops the system with the user as the center, the degree of user participation is greatly improved, and the developed system meets the needs of users, thus increasing user satisfaction and improving the success rate of system development
(3) Since the user participates in the whole process of system development, it is easy to understand and accept the function and structure of the system, which is conducive to the handover of the system and the operation and maintenance of the system.
(4) It can be seen from the above analysis that the advantage of the prototype method lies in the fact that it can confirm user needs more effectively. Intuitively, the prototyping method is suitable for system development with unclear requirements.
Strictly speaking, the current prototyping method is not an independent system development method, but a development idea . It only supports the rapid generation of system prototypes in the early stage of system development, and does not specify which method must be used in the prototype construction process. Therefore, it is not a methodological system in a complete sense. This means that the prototyping method must be used in combination with other information system development methods. The prototyping method is used to obtain and analyze requirements , and the modified and determined prototype system is used as the basis for system development. On this basis, the user requirements specification is perfected .
1.2.4 Service-Oriented Approach
OO applications are built on top of classes and objects, and then developed modeling techniques group related objects according to business functions, forming the concept of components. For cross-component function calls, it is exposed in the form of interfaces . Further decoupling the definition and implementation of the interface (high cohesion, low coupling) will give birth to services and service-oriented (Service-Oriented, SO) development methods.
From the application point of view, the intercommunication and interoperability of various application systems within and between organizations directly affect the organization's grasp of information and processing speed. How to make information systems quickly respond to demands and environmental changes, improve system reusability, information resource sharing, and interoperability between systems has become a key issue that affects the efficiency of informatization construction, and SO's way of thinking just satisfies this need. At present, the SO method is a relatively new field, and many researches and practices have yet to be further deepened. However, it represents a new system development idea that is not limited to specific technical implementation methods, and has become a general trend of information system construction. More and more organizations have begun to implement SO information systems.
--------Reference intercepted from "National Computer Technology and Software Professional Technical Qualification Level) Examination Designated Book-- Information Department Project Manager Tutorial "