Systems thinking and systems thinking is "Yi Jin Jing" in the field of thinking, is thinking and methodology has focused on the vital.
Feature of the system
Five Features
Whole greater than its parts
The whole is greater than the sum of its parts, is a classic saying about the system.
Why is part of the whole is greater than the sum of it? The principle consists in form and function of partial complementarity, combination and cooperation . For example, a developer, a design, a product that can make up a product development team, because their skills are complementary, and collaboration created through a combination of a system with product development capabilities; and three through good design and product development without the people, but can not make up a product development team, because their skills are not complementary, and the combination is difficult to collaborate on the development of the product level.
stability
There is a relatively stable system. Stability that satisfies the necessary and sufficient in the form of relation between parts and members.
Openness
The system is not isolated, but closely associated with the environment around the system. Exchange and collaboration systems and the environment, form the basis of a higher-level system.
Hierarchy
The system is composed of a plurality of levels of subsystems, each subsystem meet the system characterized in comprising the recursive nature. Stability and openness form the basis of hierarchy.
Dynamic changes
On the basis of stability and openness on the exchange system with the outside world of matter and energy, which prompted the system also changes the dynamic. This dynamic change, the attenuation can make the system stability, it may enhance the stability of the system.
Example: Software System
Software system, embodies the five main characteristics of the system.
- Whole greater than its parts. Software systems work together is formed by a large number of logic cells, each logic cell only complete a single function, and harmonious cooperation only logical units that constitute the visible features and services software.
- stability. Stability of the software system, depending on the code written accuracy and robustness, stability of the server to run the program, as well as with the service request traffic load under control.
- Openness. Interactive software system through the client, the space available to a user operation, and in response to the operation returns the user to achieve the openness of external interaction with the target; UAV software interacting with the system and by the other software systems for data exchange, to achieve open.
- Hierarchy: each subsystem, sub-modules, sub-components of the internal software system, is composed of a plurality of subsystems, sub-modules, sub-assembly and form relationships in turn composed of lower level subsystems, sub-modules, sub-assembly, and constitute a form of relationship.
- Dynamic Change: With more code components, modules, software subsystem to the existing system, the bearing capacity, stability, and so open in the event of a change. If the software can continue to adapt to the needs, we will be able to grow and develop; on the contrary, can not meet the required, or poor stability, or competition defeated the software, it can only withdraw from the market gradually disappearing.
Understanding of the system
What systems are? The system is a set of elements between the elements and form relationships with a certain posed by function and value of the whole .
From the basic level to understand the system, you need:
- Familiar features and boundaries of the system;
- Identification system elements and their functions;
- Combination and cooperation between the elements of the identification system.
These are the prerequisite knowledge system requirements. On this basis, explore the transformation and optimization system implementation, system impact, system applicability of the system.
Implementation of the system can come from understanding the function and form.
- Function: is the meaning of existence of the system. Systems to provide certain services through output function and value.
- Form: a carrier function support, necessary and sufficient to achieve relations functions.
Function and form to meet the level and stability characteristics. Usually in the form determines function.
Functional Analysis
Functional analysis, the OPM may be employed, a process of the operands in combination. Usually be "verb + noun" to express, such as auto function is to "load + people", air-conditioning function is to "regulate + temperature and humidity, people feel comfortable," the network's function is to "+ data transmission." Functional analysis, identification system need to be combined and the number of operation processes, conversion of the operand, the process.
Functional relationship to the number of operations for the share exchange. Operand in the flow occurs during the expected transition, the output to the outside to provide services. Sharing and exchanging operation of the process and the number of combination, constitutes a system function value passageway .
From the perspective of human needs, the function of the system is divided into four dimensions: satisfaction, disappointment, surprise, surprise. Satisfaction is a system function in line with expectations; disappointment is the system function failed to meet people's expectations; refers to incidental surprise function of the system to bring people great value; accident incidental feature means that the system gives a big trouble.
Formal analysis
Form, elements of the system is relatively stable structural relationship combined with the collaboration. Due to the nature of the diverse elements, and the structure of the relationship is relatively fixed, therefore, to explore the possible structural relationships.
Exploring the relationship between structure, common method is to decompose. Decomposition, the complex system is divided into a plurality of subsystems, and combinations thereof simpler and collaboration. Decomposition, can be the system architecture . This architecture includes both the basic structure of relations at different levels of subsystems, including the basic structure of the relationship between subsystems on the same level.
The basic structure of the relationship are:
- Hierarchical relationships: low level to a high level of service, form the basis for high-level;
- Sequence relations: has, in parallel with the sequence of events;
- Positional relationship: upper, lower, left, right, front, rear, surround;
- Contacting relationship: embedded, bonded, adhered, without touch;
- Connection relationship: aligned, chain, tessellation mesh;
- Mapping relationship: for example 1: 1, 1: N, N: N;
- Complementary relationship: an interface slot, the Community;
- Exchange relationship: data and information, the exchange of matter and energy;
- Logic: true and false, or with, the circulation condition;
- Mechanics relationship: gravity, momentum, force;
Example: Software System
The fundamental functions of the software system is processing data. Enter the specified data, output and display the specified data, in line with expectations.
In the form of a software system, comprising main data, instructions, and the relationship between the form of data and instructions. Form of the relationship between data and instructions, mainly having the ability to convert data processing instruction; related instruction and the instruction form, mainly in the logic and sequence relationships.
Further, execution of the instructions may have a hierarchy. A plurality of instructions can be combined into a more level routines, such as assembly. In the component level, the main structural relationship is a mapping, complementary, connection, switching, hierarchical relationships. These constitute a form of relationship between software systems.
Systematic approach
Top-down and bottom-up
The method of the system, usually top-down and bottom-up two kinds.
Top-down from the high level functionality of the system as a starting point, down layer decomposition, design and concept of a plurality of levels of functional subsystems; bottom-up, from the bottom of the element as a starting point, be clear elements and relationship form, then up layer by layer composition to achieve different levels of form and function subsystem.
In the design phase, usually top-down, avoiding lost in the labyrinth system; in the implementation phase, usually from the bottom up, to be achieved because of the characteristics of functional subsystems and elements in the form of relationship.
In the process of constructing form and function (sub) systems, often to think alternately jumps between form and function in the field. To continue thinking in the form of field depth, and then continued in-depth thinking about jumping into functional areas. vice versa.
View and Projection
Function and form to make the system more intuitive, it is necessary with a certain visualization tool system is depicted.
There are two views: an integrated view and projection view. Integrated view, depicting the main high-level view of the system, and comprising a functional relationship in the form of its subsystems; projection view, depicting the major functions and relationships form the internal configuration of the low-level subsystem, subsystem, or that, from a certain angle a cross-sectional view of the system observed. You can create an integrated view, and then through a projection at different angles to obtain projection views.
Integrated view, the OPM may be employed; projection views may be employed UML or SysML. Readers can access to information on their own, not mentioned here.
Affect the system
The system is open. Exchange system and the environment, reflecting the impact of the system.
System functions and environmental needs is a two-way effect, mutual adaptation. On the one hand, changes in environmental requirements, functional requirements of the system to adapt, to change the function of the system, its form will change, which contributed to the evolution of the system, is an example of the evolution of man; on the other hand, the form and function of the system advanced, will lead and affect the environment, to promote environmental adaptation system up to a certain extent, such as Apple leading the mobile phone in the IT industry. In either case, the system functions and the environment will reach the final of mutual adaptation.
Under normal circumstances, a leading climate change adaptation system. When the environment changes play a leading role, the system must make the transformation and optimization, to adapt to changes in the environment, otherwise, the system will gradually decline and demise. Reconstruction and optimized system, must be carried out on the basis of the principle of form and function. Change form, thereby changing the function, to adapt to environmental changes.
summary
Systems thinking and systems thinking, is a very powerful idea and methodology. This article discusses the main features of the system, affecting the form and function of the system, the basic method of the system, the system of preliminary outline of the profile system knowledge. Road system, the road ahead will be long Come.