With the more and more extensive applications of Internet, it is originally based on local area network-based enterprise network to start using Internet technology to build and transform their own enterprise network, inTranet. Thus, an emerging architecture Browser / Server came into being, and rapidly developed a new architecture that many manufacturers competed. Essentially, Browser / Server is also a CLIENT / Server structure, which is a special case for the three-layer Client / Server structure developed by traditional Layer CLIENT / Server structures. In the Browser / Server system, users can send a request to many servers distributed on the network through the browser. The Browser / Server structure has greatly simplified the client's work. You only need to install, configure a small amount of client software on the client, and the server will take more work. The execution of the database access and the execution of the application will be on the server. carry out. Under the Browser / Server three-layer architecture, the presentatio, a function layer (data service), the data layer is cut into three relatively independent units:
level one
Indicates the layer: web browser contains the display logic of the system in the representation layer, located on the client. Its task is to make a service request from a web browser to a web server on the network, and the web server authenticates the user's identity and uses the HTTP protocol to transfer the required homepage to the client, the client accepts the homepage file, And display it on a web browser.
Second floor
Function layer: Web server with application extension features contains system transaction logic in the function layer, located in the web server side. Its task is to accept the user's request, first requiring the corresponding extension application to connect to the database, file a data processing application to the database server via SQL, and then submitted the data processing to the web server, and then The web server is transferred back to the client.
the third floor
Data layer: The database server contains the data processing logic of the system in the data layer, located in the database server. Its task is to accept the request for the Web server on the database manipulation, implement the database query, modification, update, etc., submit the run results to the web server. Careful analysis is not difficult to see, the three-story Browser / Server architecture is to separate the transaction logic module of the Layer 2 Client / Server structure from the client's task, which is burdening its task, which client The pressure is greatly reduced, and the load is equalized to the web server, so that the original two-layer Client / Server structure is converted to three Browser / Server structures. This three-layer architecture is shown below. This structure not only liberates the client from a heavy burden and continuous improvement of its improved performance, but also frees the technical maintenance personnel from heavy maintenance upgrades. Since the client points the transaction logic to the function server, the client suddenly "slim", it is no longer responsible for handling key transactions such as complex computing and data access, only responsible for the display section, so maintenance personnel no longer The maintenance work is running between each client, and puts the main energy in the function server update. This three-layer structure layer is independent of each other between the layers, and the change in any layer does not affect the function of other layers. It fundamentally changes the defects of the traditional Layer CLIENT / Server architecture, which is a deep change in the application system architecture. The comparison of the two architecture is all the advantages of the Client / Server architecture than the Client / Server architecture, but also unique advantages of the Clinet / Server architecture: open standards: Client / Server uses the standards that can be uniform internally, and its applications are often dedicated. The standards used by Browser / Server are open, non-special, and is determined by standardized organizations, not the single manufacturer, to ensure the versatility and cross-platformability of their applications. Lower development and maintenance costs: Client / Server applications must develop dedicated client software, whether installation, configuration or upgrade, need to be implemented on all clients, greatly waste humanity and material. Browser / Server applications only need to have a general browser in the client, maintenance and upgrade work in the server side, do not need to change any changes to the client, so greatly reduces the cost of development and maintenance. Using simple, interface friendly: Client / Server user interface is determined by the client software, the method and interface of its use are different, and each to promote a Client / Server system requires users to learn from the beginning, difficult to use. Browser / Server user interface is unified on the browser, the browser is easy to use, interface is friendly, do not need to use other software, and solve the user's use problem. Client Swelling: Client / Server's client has the function of displaying and processing data, which is very high for the client, is a "fat" client. Browser / Server clients no longer be responsible for the tasks of the database access and complex data calculations, only need to display, which fully exerts the powerful role of the server, which greatly reduces the requirements for the client, the client becomes Very "thin". The system flexible: Part of the three partial modules of the Client / Server system needs to be changed to associate changes to other modules, making the system extremely difficult to upgrade. The three parts of the Browser / Server system are each relatively independent. The other modules are not affected when some of the modules changes, and the system improvements become very easy, and the products of different manufacturers can be used to form a better system.
