B/S structure and C/S structure

In recent years, with the continuous development of network technology, especially the rapid development of web-based information publishing and retrieval technology, Java computing technology and network distributed object technology, as a result, the architecture of many application systems has evolved from the C/S structure to a more flexible B/S multi-level distribution structure, and the network architecture of software systems has entered a new stage. Understanding the characteristics of these structures and selecting the system based on the actual situation is critical to the successful development of a MIS system.

1 C/S structure and B/S structure

1.1 C/S structure

The C/S structure, that is, the client/server (Client/Server) structure. This structure stores the database content on a remote server and installs the corresponding software on the client. The C/S software generally adopts a two-layer structure, and its distribution structure is 1. It consists of two parts: the front-end is the client, that is, the user interface (client) combines the expression with the business logic, accepts the user's request, and requests to the database service, usually a PC; the backend is a server, that is, the Data Management (server) submits the data to the client, and the client computes the data and presents the result to the user. It also provides comprehensive security protection and data integrity processing, and allows multiple customers to access the same database at the same time. In this structure, the server hardware must have sufficient processing capabilities to meet the requirements of various customers.

The C/S structure is very mature in technology. It is mainly characterized by strong interactivity, secure access mode, low network traffic, fast response, and conducive to processing a large amount of data. HoweverProgramIt is targeted development, changes are not flexible enough, and maintenance and management are difficult. Generally, it is limited to a small LAN, which is not conducive to expansion. In addition, because each client of this structure needs to install the corresponding client program, the distribution function is weak and the compatibility is poor, so the rapid deployment and installation and configuration cannot be achieved, so the lack of versatility, it has great limitations. Technical personnel with a certain level of expertise are required to complete the process.

1.2 B/S structure

B/S structure, that is, the Browser/Server structure, is to install and maintain only one server, and the client uses the browser (Browse) to run the software. With the rise of internet technology, it is a change and improvement of the C/S structure. It mainly utilizes the mature WWW browser technology, combined with a variety of script languages (VBScript, JavaScript ...) And ActiveX technology, is a new software system construction technology. Screen. Width-500) This. style. width = screen. Width-500;
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The B/S layer-3 architecture adopts a layer-3 client/g middleware structure. A layer structure is added to the data management layer (server) and user interface layer (client), called middleware (middleware ), make the entire architecture three layers. The three-layer structure is emerging along with the maturity of middleware technology. The core concept is to use middleware to divide applications into three different processing layers: presentation layer, business logic layer, and data storage layer, as shown in figure 2. The division of the three layers is logically divided. The specific physical division can have multiple combinations. As a basic platform for constructing a three-layer application system, middleware provides the following functions: it is responsible for the connection and communication between clients and servers, servers and servers, and achieves efficient connection between applications and databases; A three-tier application development, operation, deployment, and management platform is provided. This layer-3 structure is independent of each other. Any layer change will not affect the functions of other layers.

In the B/S architecture system, a user sends a request to many servers distributed on the network through a browser. The server processes the browser request and returns the user's required information to the browser. Other tasks, such as data request, processing, result return, dynamic web page generation, database access, and application execution, are all done by the Web server. As windows embeds browser technology into the operating system, this structure has become the preferred architecture for today's application software. Obviously, B/S structure applications are greatly improved compared with traditional C/S structure applications.

The main characteristics of the B/S structure are strong distribution, convenient maintenance, simple development, strong sharing, and low total cost of ownership. However, due to data security issues, high server requirements, slow data transmission speeds, and a significant reduction in software personalization, these shortcomings are obvious and difficult to meet special functional requirements in traditional modes. For example, it is difficult and inconvenient to input large amounts of data or respond to reports, and print and output specific data in a browser. In addition, it is difficult to construct complex applications. Although ActiveX, Java and other technologies can be used to develop more complex applications, the development of these technologies is complex compared with a series of application tools that have developed very mature C/S, there is no mature technical tool for use.

2 Analysis and Comparison of C/S structure and B/S structure

2.1 different hardware Environments

C/s is built on a LAN and provides connection and data exchange services through dedicated servers. The user to be processed is not only fixed but also in the same region and requires the same operating system. B/S is based on the wide area network and its information is managed by itself. It has a stronger adaptability than C/S. Generally, only the operating system and browser are available. The relationship with the operating system platform is minimal. Oriented to unknown user groups.

2.2 different structures

The C/S software generally adopts a two-layer structure, while the B/S adopts a three-layer structure:

The difference between the two structures is that the client participates in the operation in the two-layer structure, while the client does not participate in the operation in the three-layer structure, but simply receives the user's request and displays the final result. Because the client in the layer-3 structure does not need to participate in computing, it has low requirements on the computer configuration of the client. Although CSG uses a logical three-tier structure, the physical network structure is still the original Ethernet or ring-shaped network. In this way, the communication between the first layer and the second layer, and between the second layer and the third layer all occupy the same network line, resulting in a large amount of network communication. C/S only has two layers. The network traffic only includes the traffic between the client and the server, and the network traffic is low. Therefore, the ability of C/S to process a large amount of information is incomparable to that of B/S.

2.3 different processing Modes

Compared with C/S, the B/S processing mode greatly simplifies the client. You only need to install the operating system, network protocol software, and browser, and then the client becomes a thin client, the server concentrates on all application logic.

2.4 Different Component Reuse

In terms of component reusability, the C/S program has a low degree of reusability. The middleware corresponds to multiple structures, requiring components to have relatively independent functions and good reusability.

2.5 different system maintenance

System maintenance is the biggest part of the software lifecycle. Due to its integrity, the C/S program must comprehensively investigate and handle problems. In the B/S structure, the client does not have to be installed and maintained. The B/S structure only changes individual components in component composition, and development and maintenance work is concentrated on the server side. To upgrade the system, you only need to update the software on the server without changing the client software. In this way, the cost and workload of system maintenance and upgrade are reduced, and the total cost of ownership (TCO) of users is greatly reduced.

2.6 different security requirements

Because c/s adopts a paired point-to-point structure mode and adopts network protocols suitable for LAN and better security (such as netbeui protocol of NT), the security can be well guaranteed. C/s is generally oriented to a relatively fixed user group, and the program pays more attention to the process. It can perform multi-level verification on permissions, provide a safer access mode, and have strong information security control capabilities. Generally, the C/S structure is suitable for highly confidential information systems. B/S adopts the Open Structure Mode of point-to-point and multi-point-to-point, and applies TCP/IP to Intemet open protocols, its security can only be guaranteed by databases that manage passwords on data servers. Therefore, B/S requires higher security and access speed than C/S. However, these key security problems in Intemet technology are far from being solved.

2.7 different speeds

Because C/S has a lower logical structure than B/S, C/S performs faster than B/S for the same task. This makes c/s easier to process large amounts of data.

2.8 interaction and information flow are different

Strong interactivity is an inherent advantage of C/S. In C/S, the client has a complete set of applications, which have powerful functions in error prompt and online help, and can switch between subprograms freely. Although B/S provides some interactive capabilities by JavaScript and VBScript, it is too limited compared with a complete set of client applications of C/S. The information flow of C/S is single, and B/S can process information such as B-B, B-C, B-G and has a flow change.

3 architecture based on B/S structure and C/S structure

In conclusion, the two technologies B/S and C/S have their own advantages and disadvantages.

C/S technology is the mainstream development technology 20 years ago. It is mainly limited to the needs of the internal LAN. As a result, it lacks some features as an application platform and is difficult to expand to an Internet environment, in addition, developers are required to handle system-level issues such as transaction management, message queue, data replication and synchronization, and communication security. This imposes high requirements on application developers and forces them to invest a lot of effort in solving problems other than applications. This makes the maintenance, porting, and interoperability of applications complex and becomes a major defect of C/S.

However, compared with the B/S structure, C/S technology has a longer history ". From the perspective of technical maturity, software design, and developer mastery, the C/S technology is more mature and reliable. In some cases, using 100% B/S will lead to slow system response speed, high server overhead, high communication bandwidth requirements, poor security, and increased total investment. In addition, for some complex applications, the B/S method is currently not suitable for development.
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Objectively analyzing the advantages and disadvantages of C/S and B/S, establishing a network architecture that combines C/S and B/S structures has become an inevitable trend. Only when developing and planning a system can we build an appropriate information system.

The following uses the school student management system as an example to describe this design method. The system adopts the B/S + C/S architecture, integrates ASP technology, and applies the component technology COM + and ActiveX technology on the server and client respectively. The implementation of the system is divided into three parts: ASP page, COM + component and database, which is a three-layer structure. The presentation layer consists of ASP pages for displaying web pages and calling COM + components. business logic and data access are composed of a group of COM + components implemented by VC. In order to facilitate maintenance, upgrade, and implementation of distributed applications, the business logic layer and data access layer are separated during implementation, and the ASP page does not directly call the data access layer, instead, the database is called through the business logic layer. Some functional interfaces that require web processing and meet most visitor requests adopt the B/S structure. For example, instructors can query various related information of students in their classes through Browsers; school administrators manage, maintain, and query statistics of school students and teachers through a browser. The leadership can query and make decisions on data through a browser. In this way, the client is flexible. A few functions in the background use the C/S structure, such as the database management and maintenance interface. In this way, the advantages of various modes can be fully utilized-avoiding the shortcomings of the B/S structure in terms of security, confidentiality and response speed, and the disadvantages of the C/S structure in terms of maintenance and flexibility. The implementation of COM + can be divided into three steps: the design of COM + components, the generation and programming of COM + applications. The COM + component is located in a web application, and the client sends a request to the web server. The Web server sends the request to the Web application. Web applications send data requests to the database server, and the database server returns data to the Web application. The Web server then delivers the data to the client. Some difficult functions are implemented by embedding ActiveX controls in pages.

This structure has the following advantages:

(1) Make full use of the advantages of the B/S and C/S architectures and make up for the shortcomings of the two. Fully considering the interests of users, the system is updated and maintained in a simple, flexible, and easy-to-operate manner while ensuring convenient operation by the browser queryer.

(2) Information Publishing adopts the B/S structure to maintain the advantages of thin clients. The software loaded into the client can adopt a uniform WWW browser. Moreover, because both the WWW browser and the integrated network server are based on industrial standards, they can work on all platforms.

(3) The database uses a C/S structure and connects to the database through ODBC/jdbc. This part only involves system maintenance and data updates. It does not have many disadvantages, such as the large client maintenance workload caused by the full use of the C/S structure. In addition, it can construct very complex applications on the client. The interface is friendly, flexible, and easy to operate. It can solve many inherent shortcomings of B/S.

(4) For the original application based on the C/S architecture, you only need to develop the WWW interface for release, and it is very easy to upgrade to this architecture, and retain some of the original subsystems. In this way, the resources of the existing system are fully utilized.

(5) Embedding ActiveX controls in a browser makes it difficult to implement or implement functions in a browser. For example, you can use a browser to respond to a report.

(6) divide the server into two parts: Web server and web application. Web applications use component technology to implement the logic in the three-tier architecture to achieve encapsulation.

The B/S structure and C/S structure have their own advantages and disadvantages. How to combine B/S with C/s development systems is a common concern in the development of MIS systems. In the application process, the system should be selected and constructed based on the actual situation to develop an efficient and secure application system.