1. Various development methods
(I) Self-development
Advantages: You can get a satisfactory system suitable for the unit and cultivate your own strength through system development.
Disadvantages: The development cycle is often long. It requires strong leadership and sufficient technical strength, and certain consultations are required.
(II) Commissioned development
Advantages: More trouble-saving (from the user's perspective)
Disadvantages: It is necessary to be equipped with business-proficient personnel to participate, and to check and coordinate frequently. Development costs are high and system maintenance is difficult.
(III) Purchase ready-made software package
Advantages: The most convenient (from the user's perspective)
Disadvantages: It is not easy to buy a satisfactory system that is completely suitable for the unit. It requires strong discrimination ability, and there is no question about system maintenance.
(IV) Joint development
Advantages: It is most beneficial for cultivating one's own technical strength and is more convenient for system maintenance.
Disadvantages: Both parties should cooperate sincerely and have certain systematic analysis and design strength
1. Structured system development method
(I) Basic ideas
The system engineering ideas and engineering methods are developed by oneself, and the system is analyzed and designed in a structured, modular, top-down manner according to the principle of user first. That is, the entire development process is first divided into several relatively independent stages (analysis, design, and implementation). In the first two stages, we insist on structural division and design of the system from top to bottom to bottom, and in the system implementation stage, we should insist on gradually implementing from bottom to top.
(II) Features:
1. The overall analysis and design of top-down and the system development process of gradual implementation from bottom to top
2. User first
3. In-depth investigation and research
4. Strictly distinguish the work stages
5. Fully predict possible changes
6. Engineering of the development process
(IV) Advantages and Disadvantages:
1. Advantages:
(1) Emphasize the integrity and overall nature of the system development process, and emphasize the consideration of specific analytical design issues under the premise of holism, that is, the top-down view.
(2) Emphasize the strict regional division of development stages, emphasize the strict systematic analysis and design step by step, and timely summarize each step of work, and promptly feedback and correct problems when found, thereby avoiding the chaotic state of the development process.
2. Disadvantages:
(1) The starting point is too low and the tools used are backward, which leads to the system development cycle being too long, which will cause many problems.
(2) Developers are required to fully grasp user needs, management status and possible changes in the investigation, which is not in line with people's gradual understanding of the regularity of things, and there are certain difficulties in implementing them in actual work.
2. Prototyping method
(1) Basic idea: First, the user proposes development requirements, the developer recognizes and summarizes the user's requirements, constructs a prototype based on the results of identification and induction, and then evaluates the prototype with the user. If it doesn't work at all, reconstructs the prototype; if it is not satisfied, modify the prototype until the user is satisfied, which is the final prototype, which is the system implemented.
(II) Features:
1. Follow the rules of people's understanding of things and are easy for people to accept.
2. Introducing simulation methods in the early stage of analysis, communicating people's ideas, shortening the distance between users and analysts, and solving the most difficult part of the structured method.
3. Make full use of the latest software tools, get rid of the old methods, greatly reduce the time and cost of system development, and greatly improve efficiency, technology and other aspects.
(III) Advantages and disadvantages:
1. Advantages:
(1) The development cycle is short and the cost is relatively small.
(2) Provide initial prototypes to users, making user participation more practical and constructive.
(3) Easy to use by users and reduce the training time for users.
2. Disadvantages:
(1) This method is not applicable to large systems or systems with high complexity.
(2) Difficulty in the development process management.
(3) The user saw the prototype too early and mistakenly believed that the new system was like this, which made the user lack confidence and patience.
(4) It is also easy for developers to subconsciously replace system analysis with prototypes.
III. Object-oriented development method
(I) Basic ideas
The objective world is composed of various objects, each of which has its own internal state and motion laws, and the interactions and connections between different objects form various different systems. When designing and implementing an objective system, the system is designed as a minimum set of immutable (relatively fixed) parts - objects, under the conditions of meeting the needs, which is the basic idea of the OO method.
(II) Features:
(1) Encapsulated objects are encapsulations of data and operations. Their state is described by the "properties" of data in the object, while the change of the object state can only be achieved by the "operations" in the object.
(2) An abstract object is an instance of a class. The class abstracts and encapsulates the shared properties and operations of the object. Objects created through a class automatically have the properties and operations specified in the class.
(3) Inheritance: The class can derive subclasses, and the subclass automatically inherits the properties and operations of the parent class. In the development of subclasses, it is only necessary to explain that it is different from the parent class's characteristics, which improves the reusability of the software.
(4) Polymorphism: Dynamic connections are established between objects through message delivery to realize the connection between objects. Sending the same message to different objects can trigger different operations.
(III) Advantages and disadvantages:
1. Advantages:
(1) The developed software is easy to understand and maintain.
(2) The system is maintainable and scalable.
(3) The software is reusable.
2. Disadvantages:
(1) It requires a certain amount of software basic support before it can be applied.
(2) If the OO method is used from the bottom to the top to the top to the top to the top to the top and the OO method is developed from the beginning, it will cause unreasonable system structure, irregular relationships among various parts, and other problems.
IV. Object-oriented development method
The CASE method is a method to assist system development using computer software tools. Strictly speaking, it is just a development environment rather than a development method. Other development methods are still needed during specific development. The idea is that in any of the methods introduced above, after the system investigation, each step in the development process will form a correspondence to a certain extent, and then use specially developed software tools to realize the system development process.
5. Comparison of various development methods
(1) The prototype method is suitable for the design and implementation of small local systems or systems with relatively simple processing processes.
(II) The OO method can be widely applicable to the development of various information systems, but it cannot involve the previous development links of system analysis.
(III) The CASE method has the characteristics of high automation, but it must rely on specific development methods.
(IV) The structured system development method is a method that can truly support the entire system development process more comprehensively.
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