Architecture and design pattern of software: hierarchy principle

The computer software industry is a young industry born in 1950. It has only a history of more than 50 years. In contrast, architectural design can be traced back to the Egyptian pyramid era thousands of years ago, or even earlier. Therefore, computer software designers can learn a lot from architects. There are obvious similarities between the design of computer software systems and architectural design.

If you are near New York Wall Street, you will find that there are a large number of ancient and magnificent landmark buildings scattered in the ultra-luxury residential buildings, very discord. In fact, these buildings are expensive office buildings, and the building structure is extremely strong. They are only unable to meet the demands of building computer communication equipment, elevator transformation, and so on because of the old design of the building, and have to be transformed into a residential building. This wave of IT equipment innovation that occurred in 1980s led to the demolition and reconstruction of a large number of buildings, only a few of which survived the transformation into residential buildings.

Steward brand, a famous architectural designer, examines thousands of ancient and modern buildings, especially what happened after they were built and put into use. He found that in the design of buildings, the concept of hierarchy is the basic principle.

Steward Brand said that good buildings are all built for change. Since ancient times, thousands of buildings have been built by humans, the success and failure lies in the ability to adapt to changes in requirements. But how can we achieve this? Steward Brand said: "A good architecture should separate the changing and unchanged layers." That is, buildings are divided into different change Layers Based on variability.

Figure 10 steward Brand's six s principles describe the design of a building.

Six s

"Our basic idea is that there is no such concept as a building," said Frank duy, dean of the British Institute of Architecture. "Why? "A building" is a solid concept, but a solid building does not exist. What actually exists is a fluid, which is constantly flowing and changing, it can be divided into several different layers by flow rate.

In the document [brand94], Steward brand further developed this concept. He pointed out that buildings can be divided into six levels:

· Site (location), the geographical location of a building, and the shape of the building land. The construction on the construction land will be retried every several decades, but the construction land will exist for a long time.

· The structure and infrastructure of a building are difficult to change and expensive to change. In general, the life of the infrastructure is the life of the building itself. Infrastructure life can usually be up to thirty to three hundred years. Of course, for other reasons, few buildings have lived for more than 60 years.

Obviously, the stability of the building's main structure is second only to the stability of the location. The main structure of a steel structure or a concrete structure is very difficult to change, even if the cost of a small change is too high to bear.

The Windows operating system is constantly upgraded from 9x to XP, and its internal changes are very expensive, just like the change in the main structure of the building.

· Skin (appearance), which is the appearance of a building. Because of fashion, belief, technological revolution, and large-scale renovation, the appearance of a general building changes every 20 years. For example, recent energy conservation concerns have led to a more closed and insulated building exterior.

Apparently, the solid criminal department of the Building Exterior can be compared with the main structure of the building. When the main structure of a building remains unchanged, the appearance may change appropriately. Readers familiar with windows have witnessed the changes in the graphic user interfaces from Windows 3. X to Windows 9x and Windows 2000, an early-developed application.ProgramWithout modification, you can "Change your face ".

Services: communication cables, power cables, drainage, heating, ventilation and air conditioners, as well as movable parts inside the building, such as elevators and automatic stairs. These parts are worn out every 7 to 15 years. In many cases, the worn-out parts are very closely embedded into the structure of the building, so that they cannot be simply replaced, so that the building has to be re-built.

Therefore, the design of buildings must allow the service part to be constantly updated to provide timely services for residents or businesses of buildings.

· Space Plan, the distribution of walls, ceilings, floors, and doors inside a building. The planning of commercial space often changes because of the restructuring of departments. Generally, it changes every three years, while the housing space sometimes changes every thirty years.

Obviously, space planning is subject to the basic structure and services of buildings.

· Stuff (decoration): This is something that everyone is very familiar with, such as documents, telephones, bonsai, and waste paper baskets in the office, household beds, gargle rooms, photos, kitchen facilities, lights, hair combs, etc. These things change every month, every week, every day, and every hour.

The use of these decorations depends on the internal space planning of the building, rather than the opposite.

Figure 11 steward Brand's six s principles describe the design of a building.

This is the hierarchical design principle of the architecture. The key is to divide the structure of the building according to the structural stability. The opposite of stability is the possibility of change. This design principle splits the structure into different layers based on the difficulty of change. The most stable and unchangeable structure is at the bottom, the higher the stability, the easier the change.
Therefore, Frank duy said, as a designer, you should avoid providing a 50-year solution to a five-minute problem, or provide a five-minute solution to a 50-year problem. Architects, service engineers, space planners, and interior decorators should solve problems at different time scales.