System Planning---Cost-Benefit Analysis
The commonly used methods for evaluating the economic benefits of information systems mainly include cost-benefit analysis, input-output analysis and value engineering. The break-even method is commonly used in sales pricing;
Feasibility Analysis
System planning is the first stage of the information system life cycle. Its task is to conduct a preliminary investigation of the enterprise's environment, goals and the status of the existing system. Analyze and forecast the needs of the new system, and consider the various constraints on the construction of the new system, and study the necessity and possibility of the construction of the new system. According to the needs and possibilities, give the alternatives of the proposed system. Carry out feasibility analysis on these schemes and write a feasibility study report. After the feasibility study report is reviewed and approved, the new system construction plan and implementation plan will be compiled into a system design task book.
Software Engineering---Development Model
Common agile development models include:
- extreme programming
- Adaptive Software Development
- crystal method
- SCRUM
- feature-driven development
Information System Development Methodology
The structured method assumes that the system to be developed is a structured system, and its basic idea is to divide the life cycle of the system into stages such as system planning, system analysis, system construction, system implementation, and system maintenance. This method follows the principles of system engineering, uses certain development tools, completes specified documents, and develops information systems on a structured basis in accordance with pre-designed procedures and steps. The development process of the structured method generally regards the system function as a large module first, and then further decomposes or combines it according to the requirements of system analysis and design.
The OMT method uses the idea of modeling and discusses how to build a practical application model, including object model, dynamic model and function model. The object model describes the static structure of objects in the system, the relationship between objects, attributes and operations, and is mainly realized by object diagrams; the dynamic model describes the system characteristics related to time and operation sequence, such as triggering events, event sequences, To determine the state of the relationship between events, etc., the state diagram is mainly used to realize the dynamic model; the functional model describes how a calculation obtains the output value from the input value, it does not consider the order of calculation, and mainly uses DFD to realize the functional model. Simply put: the functional model indicates what happens, the dynamic model determines when it happens, and the object model determines what happens.
Software Engineering---Information System Development Method
OO application components are based on 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 leads to services and a service-oriented approach. It can be seen that object-oriented, component-based, and service-oriented are three progressive abstraction levels.
The SO approach has three main levels of abstraction, operations, services, and business processes. Operations at the lowest level represent transactions of a single logical unit, and execution of an operation typically results in the reading, writing, or modification of one or more persistent data items. The operation of the service is similar to the method of the object. They all have a specific structured interface and return a structured response; the service at the second layer represents a logical grouping of operations; the highest-level business process is to achieve a specific business goal. A set of long-running actions or activities performed, consisting of a series of operations performed in an ordered sequence according to a set of business rules. The sequencing, selection, and execution of operations become the orchestration of services or processes, and the typical situation is to call the orchestrated services to respond to business events.
Development model:
Disposable prototypes are mainly used in interface design:
The basic idea of the disposable prototype is to make a simple interface design at the beginning, so that users can have an intuitive feeling, so that they can put forward requirements, and after the requirements are obtained, the interface prototype can be discarded.
The evolutionary prototype will keep the prototype and gradually form the final product through continuous evolution.
Information system development methods:
In the case of unclear requirements, it is very risky to adopt a structured approach and a waterfall model. The formal method has higher requirements and should be based on mathematical modeling. In this way, only extreme programming is the most suitable. Extreme Programming is agile programming, emphasizing small steps and fast running, and will continue to release small versions, which can effectively deal with unclear requirements.
Among the many development methods, the object-oriented method originated from the field of simulation, and its characteristic is that the description of the system and the representation of the information model correspond to the objective entity, which is in line with people's thinking habits and is conducive to the interaction between users and developers during the system development process. Communicate and communicate, shorten the development cycle, and provide accuracy and efficiency in system development. The service-oriented method takes the coarse-grained and loosely coupled system functions as the core, emphasizes the standardization and componentization of the system, and strengthens the flexibility, reusability and evolution of the system.
Development model:
The functions of the four phases of RUP are:
- The task of the initial phase is to establish a business model for the system and define the project boundaries. In the initial phase, all external entities that interact with the system must be identified, and the characteristics of the system's interaction with external entities must be defined. In this phase, the focus is on the main risks to the business and requirements of the overall project.
- The task of the Elaboration phase is to analyze the problem areas, establish a sound structure, and eliminate the highest risk elements of the project. During the Elaboration phase, decisions on the architecture must be made based on an understanding of the entire system, including its scope, major functions, and non-functional requirements such as performance, while establishing a supporting environment for the project.
- The tasks of the build phase are to develop the remaining components and application functionality, integrate these components into a product, and conduct detailed testing. In a sense, the build phase is a manufacturing process that focuses on managing resources and controlling operations to optimize cost, schedule, and quality. The main task of the construction phase is to minimize the development cost by optimizing resources and avoiding unnecessary scrap and rework; complete the analysis, development and testing of the required functions, and quickly complete the available version; determine whether the software, site and users have prepare the software for deployment;
- In the handover phase, when the baseline is complete enough to be installed in the end user's actual environment, it enters the handover phase. The focus of the handover phase is to ensure that the software is available to end users. The main tasks of the handover phase are to test and produce a product release version; to finalize end-user support documents; to determine the new system according to user needs; to train users and maintenance personnel; to obtain User feedback on the current version, based on which the product is adjusted, for example, by debugging, performance or usability enhancements, etc.
Information system life cycle:
System planning is the first stage of the information system life cycle. Its task is to conduct a preliminary investigation of the enterprise's environment, goals and the status of the existing system. Analyze and forecast the needs of the new system, and consider the various constraints on the construction of the new system, and study the necessity and possibility of the construction of the new system. According to the needs and possibilities, give the alternatives of the proposed system. Carry out feasibility analysis on these schemes and write a feasibility study report. After the feasibility study report has been reviewed and approved, the new system construction plan and implementation plan will be compiled into a system design task book.
According to the main tasks of system planning, the system planning can be carried out according to the following steps:
- Conduct a preliminary investigation on the existing system, collect various information from similar companies and the company according to the company's strategy and development goals, observe the current situation of the company from the perspective of the management, and analyze the operation of the existing system
- Analyze and determine the goals of the system. System goals should include the quality and scope of services, policies, organizations and personnel, etc. It not only includes the goals of the information system, but also reflects the goals of the entire enterprise.
- Analyze the composition and basic functions of subsystems. The system is divided from top to bottom, and the functions that each subsystem should implement are specified in detail.
- Draft the implementation plan of the system. Subsystem priorities can be set to determine the order in which subsystems are developed
- Carry out a systematic feasibility study, write a feasibility study report, and hold a feasibility discussion meeting.
- Develop a system construction plan. Analyze and compare the various technical indicators proposed in the feasibility study, and implement the preconditions of various assumptions, formulate a system construction plan, and compile a system design task book according to the plan and implementation plan, and the system design task book is approved by the superior supervisor After approval by the department, it will be formally used as the basis for system construction.
Development model:
The spiral model, which combines the waterfall model and the rapid prototyping model, emphasizes the risk analysis that other models ignore, and is especially suitable for large and complex systems. The spiral model iterates several layers along the spiral, divided into the following four activities:
- Develop a plan: identify software goals, select an implementation plan, and clarify project development constraints
- Risk analysis: analyze and evaluate the selected solutions, consider how to identify and eliminate risks
- Implementation engineering: implementation of software development and verification;
- Customer evaluation: Evaluate the development work, put forward correction suggestions, and formulate the next step plan;
The spiral model is driven by risk, emphasizes alternatives and constraints to support software reuse, and helps to incorporate software quality as a special goal into product development. However, the spiral model also has certain restrictions, as follows;
- The spiral model emphasizes risk analysis, but it is not easy to require many customers to accept and detail this analysis, and to make relevant responses. Therefore, this model is often adapted to internal large-scale software development
- There is no point in performing a risk analysis if performing the risk analysis will greatly affect the profit of the project, therefore, the spiral model is only suitable for large-scale software projects;
- Software developers should be good at finding possible risks and analyzing risks accurately, otherwise it will bring greater risks
The first is to determine the goals of a stage, complete the options and constraints of these goals, and then analyze the development strategy of the plan from the perspective of risk, try to eliminate various potential risks, and sometimes it needs to be completed by building the original. If certain risks cannot be ruled out, the program is terminated immediately, otherwise the next development step is started. Finally, the results of this phase are evaluated and the next phase is designed.
Development model: Agile development includes the following seven types
- In Extreme Programming, the core ideas are communication, simplicity, feedback, and courage. Knowing that plans cannot keep up with changes, Extreme Programming does not require developers to do a lot of documentation at the beginning of the software. Extreme Programming emphasizes the advocacy of testing first, in order to minimize the chance of bugs in the future.
- SCRUM is an iterative and incremental process for product development or working principles. It is an empirical process framework that can integrate various development events. The importance of releasing products in SCRUM is above all else. It is an improvement on the iterative object-oriented method, which seeks to seek a development method that takes full advantage of object-oriented and component technology.
- The feature-driven method FDD is a set of development models for small and medium-sized software development projects. In addition, FDD is a model-driven rapid iterative development process. It emphasizes simplicity, practicality, and easy acceptance by the development team. It is suitable for frequent changes in requirements. s project
- ASD (Adaptive Software Development) ASD emphasizes the applicability of development methods. This idea comes from the chaos theory of complex systems. ASD does not have many specific practices like other methods. It focuses more on providing the most fundamental aspects of the importance of ASD. and explain why the development approach is adaptive from a higher organizational and management perspective
- DSDM (Dynamic System Development Method) is one of many agile development methods, which advocates fast and effective system development with business as the core. Practice has proved that DSDM is one of the successful agile development. In the UK, it has become the most widely used rapid application development methodology due to its success in software organizations of all sizes. DSDM not only follows the principles of agile methods, but also is suitable for those mature traditional development methods and software organizations with a solid foundation.
- Lightweight RUP. RUP is actually a process framework that can accommodate many different types of processes. CL believes that RUP should be used in an agile way. Emphasize that the Agile method of advancement is nothing more than RUP's mainstream OO development methodology.
ITIL information technology infrastructure library believes that service management is its core module, which includes two process groups of service provision and service support
Extreme programming is an important agile development method, including the rules and practices of the four framework activities of planning, design, coding and testing. The important technology used in extreme programming is refactoring, which includes the refactoring of design technology and the refactoring of construction technology; extreme programming advocates that after the basic design is completed, the team should not start coding directly, but develop a series of Detect unit tests including all stories (Story) released this time; one of the key concepts in extreme programming activities is "pair programming", recommending that two people face the same computer to develop code together; unit tests established during extreme programming A framework that can be automatically implemented should be used to support immediate regression testing strategies after code changes
The spiral model is an evolutionary software process model that combines the systematic and controllable features of the prototype development method and the waterfall model. It has two notable features, one is to adopt a cyclical approach to gradually deepen the depth of system definition and implementation while reducing risks; the other is to determine a series of milestones to ensure that stakeholders in the project development process support feasible and compelling Satisfactory system solution.
