Preliminary understanding of b/s--

First, c/s introduction1. Concept

that is, the client and server structure . It is a reasonable allocation of tasks to the client side and server side to achieve, reduce the communication overhead of the system, can make full use of the advantages of both sides of the hardware environment.

Servers typically employ high-performance PCs, workstations, or minicomputer, and employ large database systems such as Oracle, Sybase, Informix, or SQL Server. The client needs to install the dedicated client software.

2. Advantages and Disadvantages

The advantages of C/s:
is to give full play to the processing power of the client PC, a lot of work can be submitted to the server after the client processing. The corresponding advantage is that the client should respond faster.

Disadvantages of C/s:

(1) The client is relatively large, the installation is a bit complicated .
(2) In the client needs to configure the connection database information, the client software directly linked to the database, there is a security risk .
(3) When the amount of data is large, the client responds relatively slowly. Because the client wants to download the server-side data over the LAN to the client computer and then analyze the processing.
(4) remote use is not flexible , and enterprise data is not secure if you want to remotely use a port that must open a database to intetnet.

3, three layer and C/s structure of the combination(1) three layer C/s structure software in the past, now, or in the future is a strong functional enterprise management software mainstream application platform. (b/S structure is also one of them, but it is restricted by IE browser and Web server to die, so can not be qualified in the application of complex functions. ）
(2) three layer C/s structure is to divide the application function into the representation layer, the logic layer and the data layer three parts. The solution is to explicitly split the three layers and logically make them independent.

(3) Popular speaking is: In the client is a simple EXE program, on the server side is an application server, in the background is a database. The client requests a request to the application server and the application server calls the data to the database and processes and then returns the data to the client. Functionality is implemented on the server side, and the client is not directly connected to the database.
Three-layer C/s structure does not exist in the above-mentioned C/s problems, with good stability, collapse platform, usability, strict data security.

Second, b/s introduction1. Concept

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.

2. Advantages and Disadvantages

Advantages of b/s :

(1) The distribution is strong, maintenance is convenient, the development is simple and the share is strong, the total cost of ownership is low .

(2) The biggest advantage is that you can operate anywhere without having to install any specialized software .

As long as there is a computer can use the Internet, the client 0 maintenance. System extension is very easy, as long as the Internet, and then by the system administrator assigned a user name and password, it can be used. With Internet/intranet technology, more customers are supported for WAN environments. The Web server, application server can be dynamically configured to ensure system performance based on traffic.

Client only need standard browser with object-oriented technology, code reusability is good, system expansion maintenance simple development cost is high, development cycle is long

The disadvantages of B/s:

(1) Slow execution speed .

b/s structure of software customers through IE browser to operate,.
(2) The security is relatively poor .

If placed directly on the Internet is more dangerous, IE and Web servers are the focus of viruses and hacker attacks. Internet Explorer virus is a frequent thing, as long as you accidentally on some abnormal website, ie on the strange kind of virus. The person who uses the computer IE basically has planted the virus, if your IE browser kind of virus, then your system paralysis cannot use.
(3) more data security risks .

If you use B/s to open your customer profile information, then your customer information will reside in the temporary files of this computer, the next time you do not have a server, directly in this computer has offline browsing, directly can be viewed. There are now many companies, hotels, Internet cafes are equipped with network monitoring system, you have used the system, you have seen all the data will be monitored.
(4) very poor operability .

b/S is widely known as the main use of Web pages, more suitable for viewing information. But if you do data entry, modification, printing and other operational very poor, do not support mouse drag, right-click and other common operations. Just like you use Outlook or Foxmail client software to send and receive mail conveniently, or directly to 163 of the website to send and receive mail convenient?

Second, C/s and b/ a comparison1. Form of form

2. Language description

(1) Hardware environment
C/S is established on the basis of local area network, and provides connection and data Exchange service through specialized server. The user being processed is not only fixed, but is in the same area and requires the same operating system. b/s based on the wide area network, information management, there is more than C/s to adapt to the range, generally as long as there are operating systems and browsers on the line. Minimal relationship to operating system platform. Target an unknown user base.

(2) structure
c/s software generally adopts two-layer structure, while B/s adopts three-layer structure:
The difference between the two structures is that the client participates in the two-tier structure, and the client in the three-tier structure does not participate in the operation, but simply receives the user's request and displays the final result.

because clients in a three-tier structure do not need to participate in the calculation, the client's computer configuration requirements are low. Although B/S uses a logical three-layer structure, the physical network structure is still the original Ethernet or ring network.

in this way, the communication between the first layer and the second layer structure, the communication between the second layer and the third layer structure must occupy the same network line, and the network traffic is large. and C/s only two layer structure, network traffic only includes the traffic between client and server, network traffic is low. Therefore, C/s to deal with a large amount of information capacity is B/s incomparable.

(3) Processing mode
b/s processing mode compared with C/s, greatly simplifies the client, as long as the operating system, network protocol software and browser, then the client becomes a thin client, and the server is centralized all the application logic.

(4) Component Reuse
in the reuse of component, the C/S program is considered from the whole and has low reusability. The BLS corresponds to multiple structures, which requires the component to have relatively independent function and has good reusability.

(5) System maintenance
system maintenance is the most expensive part of the software life cycle.

Because of its entirety, the C/s program must investigate and deal with the problems in its entirety. and b/S structure, the client does not have to install and maintenance.

The b/s structure only changes individual components in component composition, and the development and maintenance work is concentrated on the server side. When upgrading is required, only update the server-side software without having to replace the client software to achieve a seamless system upgrade. This reduces the cost and effort of system maintenance and upgrades, greatly reducing the total cost of ownership (TCO) of the user.

(6) Requirements for safety
because C/s adopts paired point-to-point structure mode, and adopts network protocol (such as NT NetBEUI protocol) which is suitable for LAN and security, the security can be better ensured.

c/S generally oriented to a relatively fixed user base, the program more focused on the process, it can be multi-level verification of permissions, providing a more secure access mode, the ability to control information security is very strong. Generally highly confidential information system using C/s structure is suitable.

and b/s using point-to-multipoint, multi-point to multi-point of this open structure mode, and the use of TCP/IP as a kind of open protocol used in Intemet, its security can only rely on the data server Management password database to ensure. So b/s for security and access speed than C/s have higher requirements. These key security issues in Intemet technology are far from resolved.

(7) different speed
because c/s in the logical structure than b/s less layer, for the same task, C/s to complete faster than B/s. Makes C/s more advantageous to deal with large amounts of data.

(8) Interactivity is different from the flow of information
Strong interactivity is an inherent advantage of C/s.

In C/S, the client has a complete set of applications that have powerful functions in terms of error hints, online help, and can be freely switched between subroutines.

Although the B/s is provided with some interactivity by JavaScript and VBScript, it is too limited compared with the client application of C/S. The information flow of C/S is single, and b/s can be processed such as B-b, B-C, b-g etc. and has the change of flow direction.

Preliminary understanding of b/s--