c/S and b/s

c/S structure, that is, client/server (client/server) structure, is well-known software system architecture, through the rational allocation of tasks to the client side and server side, reduce the communication overhead of the system, can make full use of the advantages of both ends of the hardware environment. Early software systems used this as the preferred design standard.
b/s structure, that is, Browser/server (browser/server) structure, with the rise of internet technology, a change of C/s structure or improved structure. In this structure, the user interface is implemented completely through WWW browser, some transaction logic is implemented at the front end, but the main transaction logic is implemented on the server side to form the so-called 3-tier structure. b/s structure, mainly using the continuous mature WWW browser technology, combined with the browser of a variety of script language (VBScript, JavaScript ...) and ActiveX technology, with the common browser to achieve the original need for complex special software to achieve the powerful features, and save the development cost, is a new software system construction technology. With Windows 98/windows 2000 embedding Browser technology inside the operating system, this structure becomes the preferred architecture for today's application software.
c/S and b/s difference:
Client/server is built on the basis of the local area network. Browser/server is built on the basis of the WAN.
1. Different hardware environments:
c/S is generally established in a dedicated network, a small range of network environment, LAN and then through a dedicated server to provide connectivity and data exchange services.
b/S is built on the WAN, need not be specialized network hardware environment, example with telephone Internet, renting equipment. Information is managed by itself. Have more than C/s to adapt to the range, generally as long as there are operating systems and browsers on the line
2. Different for security requirements
c/S is generally oriented to a relatively fixed user group, the ability to control information security is very strong. Generally highly confidential information system using C/s structure is suitable. Can be published through the B/s part of the public information.
b/S is built on the wide area network, the security control ability is relatively weak, facing is an unknown user group.
3. Different from the program architecture
c/S program can pay more attention to the process, the authority can be multi-level check, the system running speed can be less considered.
b/S multiple considerations for security and access speed are based on the need for more optimization. More than C/s has higher requirements B/s structure of the program architecture is the trend of development, from the MS. NET series of BizTalk Exchange 2000, etc., fully support the network component Building system. SUN and IBM push the JavaBean component technology, so that b/s more mature.
4. Software reuse is different
c/S program can inevitably be considered as a whole, the reuse of components is not as good as the reuse of components under B/s requirements.
The multi-structure of B/s pair requires the relative independent function of the component. Can be reused relatively well. You can reuse the table you bought, not the stone table on the wall.
5. system maintenance is different
System maintenance is the software life cycle, the cost is big,-------important
Due to the integrity of the C/s program, it is necessary to investigate the problem and upgrade the system. Upgrade is difficult. Could be a whole new system.
b/S components, components of individual replacement, to achieve seamless upgrade of the system. Minimal system maintenance overhead. Users can download and install themselves from the Internet to achieve upgrades.
6. Handling problems differently
c/S program can handle the user face fixed, and in the same area, security requirements of high demand, operating system-related. Should all be the same system.
b/S is built on the wide area network, facing different user groups, dispersed area, this is the C/s can not be made. Minimal relationship to operating system platform.
7. User interface is different
C/S is established window platform, the performance method is limited, the programmer generally requires higher
b/S is built on the browser, there is more rich and vivid expression way to communicate with users. And most of the difficulty is reduced, reducing development costs.
8. Different information flow
c/S program is typically a centralized mechanical processing, the interaction is relatively low
b/S information flow can change, b-b b-c b-g and other information, flow changes, more like the trading center

3-tier:

The role of each layer1: Data access layer: mainly for the original data (database or text files, such as the form of data storage) operation layer, rather than the original data, that is, the operation of the data, rather than the database, specifically for the business logic layer or presentation layer to provide data services. 2: Business logic Layer: mainly for the specific problem of operation, can also be understood as the operation of the data layer, the data business logic processing, if the data layer is a building block, the logic layer is the building of these blocks. 3: The presentation layer: The main means of the web, can also be expressed as a WinForm way, the web can also be represented as: ASPX, if the logical layer is quite powerful and perfect, no matter how the presentation layer is defined and changed, the logic layer can provide services perfectly.