The architecture of the application

The architecture of an application is a conceptual description of the application architecture.

At present, with the rapid development of information technology, most of modern enterprises adopt distributed computer system. Increasingly intense competition requires applications to minimize the development cycle and to be highly flexible in order to adapt to the vagaries of the marketplace. All of this challenges the business and technical aspects of the developers of distributed applications.

Traditional distributed applications are mostly two-tier client/server mode (Client/server), where clients connect directly to the server, responsible for processing data and executing client applications on the client.

There are many limitations to this two-tier application architecture: The cost of customer connections, the limitations of server data formats, scalability, and so on. In particular, when the number of customers is unknown, or the number of customers can be very large, the two-tier application architecture will not be able to handle this situation.

To increase the flexibility and reusability of distributed applications, you can add a third tier to a two-tier architecture, which is the three-tier application architecture:

The presentation layer provides data to the user, presenting the user interface.

The business layer is used to implement business logic, and the presentation layer uses the services provided by the business layer.

The data access layer performs specific data access services, including retrieval and storage.

In a three-tier application architecture, the business layer is not fixed to any customers, nor does it care how the data is stored. Modifying any layer will not adversely affect the other layers. Each service is independent and can be combined in a new way to create a new application. This three-tier architecture facilitates developers to create highly scalable applications.

Note: A three-tier application does not imply three separate computers. The three-tier architecture is a logical model in which the physical model depends on where the service is provided.