System architecture design professional skills·Basics of information systems

Table of Contents of Series Articles

Professional skills in system architecture design · Network technology (3)
Professional skills in system architecture design · System security analysis and design (4) [System architect]
Advanced skills in system architecture design · Software architecture design (1) [System architect]
System Advanced skills in architecture design · System quality attributes and architecture assessment (2) [System Architect]
Advanced skills in system architecture design · Software reliability analysis and design (3) [System Architect]

现在的一切都是为将来的梦想编织翅膀，让梦想在现实中展翅高飞。
Now everything is for the future of dream weaving wings, let the dream fly in reality.

1. Overview of information systems

1.1 Definition of information system

An information system is a human-machine integrated system composed of computer software and hardware, network and communication equipment, information resources, users and rules and regulations for the purpose of processing information flow . The functions
of information systems are: input, storage, processing, output and control . The development path of information systems is divided into six stages : initialization, dissemination, control, integration, data management and maturity .

1.2 Classification of information systems

Information systems are divided into six categories: business (data) processing systems, management information systems, decision support systems, expert systems, office automation systems, and comprehensive information systems .

1.3 Information system life cycle

The life cycle of an information system is divided into four stages: generation, development, operation and demise .

1.4 Principles of information system construction

The principles of information system construction can be divided into the principle of senior management intervention, the principle of user participation in development, the principle of top-down planning, the principle of engineering, etc.

• Principle of senior management intervention : such as CIO intervention
• Principles of user participation in development : users determine the scope, core users participate in the entire process, and users deeply participate
• Top-down planning principle : to reduce information inconsistency
• Engineering Principles : Introduction of [Software Engineering]
• Other principles : principle of innovation, principle of integrity, principle of development, principle of economy

1.5 Information system development methods

Information system development methods mainly include: structured method, prototype method, object-oriented method, service-oriented method, agile method, and component-based development method .

Other information system development methods:

• Formal methods, based on strict mathematical modeling, such as clean room software engineering
• Unified Process Method [UP/RUP]
• Agile methods
• Architecture-based development method [ABSD]

2. Typical applications of informatization

The process from low-level to high-level, from local to global, from simple to complex.

2.1 Business Processing System (TPS)

Transaction Processing System (TPS), also known as Electronic Data Processing System (EDP) , is the most rudimentary form of information system used in the early days of computer management.

TPS is the lowest and most basic information system serving the organizational management hierarchy.

2.2 Electronic Data Processing System (EDPS)

Management Information System (MIS) is developed from the business processing system. It introduces a large number of management methods on the basis of TPS to process the overall information of the enterprise , and uses the information to predict, control, plan, and assist the overall management of the enterprise. information system.

There are four major components of MIS system: information source, information processor, information user and information manager .

In the decision-making process, the closed-loop structure continuously collects information and sends it to the decision-maker.

• Batch processing system belongs to [open loop system]
• Computer real-time processing system belongs to [closed-loop system]

2.3 Management Information System (MIS)

(1) Sales market subsystem. It includes sales and promotion. In terms of operational control, it includes hiring and training sales personnel, daily scheduling of sales and promotion, and regular analysis of sales volume by region, product, and customer.
(2) Production subsystem. It includes product design, production equipment planning, production equipment scheduling and operation, production personnel hiring and training, quality control and inspection, etc.
(3) Logistics subsystem. It includes purchasing, receiving, inventory control and distribution.
(4) Personnel subsystem. It includes hiring, training, appraisal records, wages and firing, etc.
(5) Finance and accounting subsystem. The goal of finance is to ensure the financial requirements of the enterprise and keep costs as low as possible; accounting is to classify and summarize financial business, fill in standard financial reports, prepare budgets, analyze and classify cost data, etc.
(6) Information processing subsystem. The function of this system is to ensure the information needs of the enterprise. Typical tasks are handling requests to collect data, requests to change data and programs, reporting hardware and software failures and planning recommendations, etc.
(7) High-level management subsystem. Serve senior leadership. Business includes retrieving information and supporting decision-making, writing documents and correspondence, and sending instructions to other departments in the company.

2.4 Decision Support System (DSS)

Decision Support System (DSS) is acomputer-based system composed of three interrelated parts: language system, knowledge system and problem processing system .

The two basic structural forms of DSS are the two-database structure and the knowledge-based structure . The actual DSS evolves from these two basic structures by decomposing or adding certain components. The two-database structure consists of a database subsystem, a model library subsystem and a dialogue subsystem forming a triangular distribution structure.

[Characteristics that DSS should have] :

(1) Data and models are the main resources of DSS.
(2) DSS is used to support users in making decisions rather than on behalf of users.
(3) DSS is mainly used to solve semi-structured and unstructured problems .
(3) The role of DSS is to improve the effectiveness of decision-making rather than the efficiency of decision-making.

Decision support system components

1. Data reorganization and confirmation. The problem with databases associated with decision support systems is getting the right data well and manipulating the data in the ideal form. This problem can be solved through the concept of data warehouse.

2. Creation of data dictionary. The data warehouse is a database that exists separately from the operation layer system. Through access to data warehouses, managers can make fact-based decisions to solve many business problems.

3. Data mining and intelligence. Once a data warehouse is built, managers need to use tools for data access and query. The tools used are called agents. Data mining result types include:

1）联合：把各个事件联系在一起的过程。例如，将学生们经常同时选修的两门课程联系起来，以便这两门课程不被安排在同一时间。

2）定序：识别模式的过程。例如，识别学生们多个学期课程的次序。

3）分类：根据模式组织数据的过程。例如，以学生完成学业的时间(4年以内，4年以上)为标准分成几个小组。

4）聚类：推导特定小组与其他小组相区分的判断规则的过程。例如，通过兴趣、年龄
工作经验来划分学生。

4. Model establishment. The purpose of model management is to help decision makers understand the phenomena related to choices. Methods for building models include finite enumeration, algorithms, heuristics and simulations.

The basic structure of DSS mainly consists of 4 parts: database subsystem, model library subsystem, reasoning part and user interface subsystem .

2.5 Expert System (ES)

Expert System (ES) is an intelligent computer program system (an important branch of artificial intelligence), which contains a large amount of expert-level knowledge and experience in a certain field . It can use the knowledge and problem-solving methods of human experts to solve problems. Address issues in the field.

Expert systems differ from traditional applications and other types of artificial intelligence problem-solving programs. Mainly manifested in the following five aspects :

(1) Expert systems belong to the category of artificial intelligence, and the problems they solve are semi-structured or unstructured problems.
(2) The expert system simulates the reasoning of human experts in the problem domain, rather than simulating the problem domain itself.
(3) The expert system consists of three elements: a comprehensive database that describes the problem status, a knowledge base that stores heuristic empirical knowledge, and an inference engine that infers the knowledge in the knowledge base. The three elements respectively correspond to the three-level knowledge of data level, knowledge base level and control level, while traditional applications only have two-level structures of data and program.
(4) The problems handled by the expert system are practical problems, not purely academic problems.
(5) From the perspective of solution methods, the expert system has strong specificity and poor versatility.

The main branches of artificial intelligence AI include expert systems, robotics, vision systems, natural language processing, learning systems and neural networks.

The composition of expert systems

• knowledge base. It is used to store the domain knowledge used by the system to solve practical problems . The knowledge in the knowledge base can be divided into two categories: one is factual knowledge, and the other is heuristic knowledge.
• Comprehensive database. It is a working memory used by the expert system to store various information required and generated during the execution and reasoning process. Therefore, the comprehensive database is also called a dynamic knowledge base, and its content is constantly changing during the operation of the system. Correspondingly, the knowledge base of the expert system is called a static knowledge base. Together they form a complete knowledge base.
• Reasoning engine. The inference engine and knowledge base together form the core of the expert system . An inference engine, also known as a control structure or rule interpreter, usually includes an inference mechanism and a control strategy. It is a set of program modules used to control the operation of the system, perform various tasks, and perform various searches and reasoning based on the knowledge base.
• Knowledge acquisition. It mainly has two functions: one is the editing and refinement of knowledge, and the other is knowledge self-learning .
• Explain the program. It is a user-oriented service and is responsible for answering various questions raised by users .
• Human-machine interface. It usually includes two parts: one is the interface between the expert system and the user, and the other is the interface between the expert system and domain experts and knowledge engineers .

2.6 Office Automation System (OAS)

Office automation is the automation of office information processing methods . What OAS wants to solve is the integrated processing of information including data, text, sounds and images. In essence, office automation is based on advanced science and technology, using relevant office automation equipment to assist office workers in managing various office information, and mainly using resources to improve office efficiency and office quality . Computer technology, communication technology, system science and behavioral science are its four pillars. Among them, behavioral science is the leading one, system science is the theoretical basis, and computer technology and communication technology are combined.

Main functions of OAS:

(1) Transaction processing . Complete a large number of tedious things in the office part, also known as transaction office system, which is divided into single-machine processing system and multi-machine processing system (communication, information sharing).
(2) Information management . The control and management of information flow mainly includes the comprehensive work of office personnel in the collection, processing, transmission, exchange, access, provision, analysis, judgment, application and feedback of information. It can be called a managed office system, which can connect various isolated transaction processes in a transactional office system through information exchange and shared resources to obtain accurate, fast, timely and high-quality results. A managed office system is a distributed processing system with computer communication and network functions.
(3) Assist decision-making . It can be called a decision-making office system. It uses a large amount of information provided by the manager-type office system as the basis for decision-making work. It establishes a computer-operable decision-making model that can comprehensively analyze, predict development, and judge pros and cons. It can automatically make decisions based on original data information. A more realistic decision-making solution.
The components of the office automation system: computer equipment, office equipment, data communication and network equipment, and software systems.

The components of the office automation system : computer equipment, office equipment, data communication and network equipment, and software systems .

2.7 Enterprise Resource Planning (ERP)

Enterprise resources can be summarized into three "flows", namely logistics, capital flow and information flow .

ERP refers to a management platform based on information technology and using systematic management ideas to provide enterprises with decision-making and operational means.

The ERP system is an information system that integrates all resources of an enterprise and conducts comprehensive and integrated management.

• Management thought: It is a change in management thought.
• Software products: You cannot buy them and use them directly. They require personalized development and deployment.
• Management system: There are many subsystems . These subsystems have unified planning and are interconnected to facilitate pre-event and ongoing monitoring .
• Includes content: financial management, logistics management, production control management, human resources management, inventory management, etc.

ERP structure :

(1) Production forecast . Market demand is the basis for the survival of an enterprise. In ERP, it is first necessary to make a more accurate prediction of the market. Forecasting is mainly used for planning. Among the five levels of planning in ERP, the preparation of the first three levels of planning, namely the business plan, production plan outline and master production plan, is inseparable from forecasting.
(2) Sales management (planning) . Sales management is mainly aimed at managing the related business of the enterprise's sales department.
Business plan (outline of production plan). It is formulated based on the production goals of the business plan. It is a refinement of the enterprise's business plan and is used to describe the enterprise's production plan in a certain period of time under the conditions of available resources.
(3) Master production plan . It is a refinement of the enterprise's production plan outline, describing the plan within a certain period of time: what to produce, how much to produce and when to deliver. The preparation of the master production plan shall be based on the production outline, and its summary result shall be equivalent to the production plan outline.
(4) Species demand planning . Material requirements planning is the network support plan and time schedule plan for all manufactured parts and all purchased parts required for each project of the master production plan. It derives the demand quantity and demand period of the parts and materials that make up the product based on the demand quantity and delivery date of the final product according to the master production plan, and then derives the production order issuance date of the self-made parts and the purchase order delivery date of the purchased parts. , and further balance between required resources and available capabilities.
(6) Capacity demand planning . It is a planning management method for accounting for the capabilities required for material requirements planning. The purpose is to analyze and compare the MRP requirements and the existing production capacity of the enterprise to find out the bottlenecks of the capacity as early as possible and provide capacity guarantee for the realization of the enterprise's production tasks.
(7) Workshop operation plan. It is based on the processing and manufacturing orders generated by MRP (i.e., self-made parts production plan), in accordance with the delivery date and production priority selection principles, as well as the production resources of the workshop (such as equipment, personnel, material availability, processing Capacity, etc.), release the production plan of parts to the appropriate workshop in the form of an order.
(8) Purchasing and inventory management . Procurement and inventory management are the basic modules of ERP. The procurement management module organizes, implements and controls the entire process of procurement, from the generation of purchase orders to the receipt of goods. The inventory management module is responsible for the entry and exit of enterprise materials. , deposit management.
(9) Quality and equipment management . Quality management runs through the entire enterprise management process. Equipment management refers to the comprehensive management of all equipment material movement forms and value movement forms within the equipment life cycle through a series of technical, economic and organizational measures based on the enterprise's production and operation goals.
(10) Financial management . Accounting work is an important part of enterprise management. It reflects and supervises the daily economic activities of enterprises in the form of currency, and classifies and summarizes the data of these economic operations to provide necessary information support for enterprise management and decision-making. Corporate financial management is the collective name for corporate accounting work and activities.
(11) ERP related extended application modules . Such as customer relationship management, distribution resource management, supply chain management and e-commerce, etc. These extension modules themselves are also an independent system, and they are often sold and implemented as independent software products on the market.

Functions of ERP :
support decision-making, provide targeted IT solutions for enterprises in different industries, and develop from an internal supply chain to an industry-wide and cross-industry supply chain.

3. Typical information system architecture model

3.1 E-Government (EG)

E-government is a systematic project that uses information technology and other related technologies to realize the integrated management and operation of public affairs, government affairs, commerce, and affairs.

The main actors (roles) are: government (Government), enterprises (institutions) (Business), and residents (Citizen). If there is a fourth category, it is civil servants (Employee).

type	Interpretation and application
Government to Government (G2G)	The flow of electronic official documents between upper and lower levels of government, different regions and different functional departments , electronic judicial files, electronic financial management and electronic statistics, etc., business transactions between governments at the same level, including the collection, processing and utilization of national and local basic information . Such as: population information, geographical information, and government decision support at all levels .
Government to Business (G2B)	Various public services are provided to enterprises , such as online tax declaration, electronic license processing, and information consulting services. Enterprises need to file taxes, and on one side is the government tax reporting department. For example: the government issues various business licenses, permits, certificates, and quality certifications to enterprises and units .
Government to Residents (G2C)	It is a service provided by the government to the public , including education and training services, public employment services, electronic medical services, social insurance services, traffic management services (online motor vehicle violation inquiries), public electronic taxation and electronic document services, etc. For example: management of community police and water, fire, natural disaster and other public safety-related information, household registration, various certificates and licenses.
Business to Government (B2G)	Enterprises pay taxes to the government Enterprises supply various goods and services to the government [including competition/bidding] Enterprises make suggestions and appeals to the government
Citizens to Government (C2G)	Various taxes and fees that individuals should pay to the government. Individuals provide feedback to the government on public opinion [ soliciting opinions from the masses ] . Alarm services [robbery, medical, first aid, fire alarm, etc.]
Government to Civil Servants (G2E)	It refers to e-government affairs , e-policies and regulations, e-official document circulation, e-office, e-training, e- financial management, civil servant performance evaluation, and government systems for internal use between the government and government civil servants, that is, government employees. For example: office automation within the department, internal work system.

3.2 Enterprise informatization (EI)

Enterprise Informatization (EI). Enterprise informatization is a process in which enterprises use current information technology to realize automation, convenience, networking and intelligence of business activities to enhance the core competitiveness of enterprises. Enterprise informatization is the integration of technology and business, and is realized from three levels: corporate strategy, business operations and management operations. The methods of enterprise informatization include: business process reconstruction method, core business application method, information system construction method, main database method, resource management method, and human capital investment method.

3.3 Electronic Commerce (EC)

Electronic Commerce (EC). E-commerce refers to the use of communication means provided by the Web to buy and sell products or provide services online, and its derivative behaviors. The main models are B2B, B2C, C2C, and O2O (online purchase of offline services).