Aptech Study Notes (1): Chapter 1: ASP. NET and web forms

Objectives:
1. Describe Web Applications
2. Describe the web application development cycle
3. Explore ASP
4. Explain ASP. NET functions

Keyword query:
I. B/S three-layer structure:

The B/S structure, that is, the Browser/Server structure, is a change or improved structure of the C/S structure with the rise of Internet technology. In this structure, the user interface is fully implemented through the WWW browser. Some transaction logic is implemented at the front end, but the main transaction logic is implemented at the server end, forming a so-called 3-tier structure. The B/S structure is mainly based on the mature WWW browser technology, combined with a variety of browser script languages (VBScript, JavaScript ...) And ActiveX technology, the use of general browsers to achieve the original need for complex special software to achieve the powerful functions, and reduce development costs, is a new software system construction technology. As Windows 98/Windows 2000 embeds browser technology into the operating system, this structure has become the preferred architecture for today's application software. Obviously, B/S structure applications will be greatly improved compared with traditional C/S structure applications.

Differences between C/S and B/S:
Client/Server is built on the LAN. Browser/Server is built on the WAN.
1. Different hardware environments:
C/s is generally built on a dedicated network. In a small network environment, the LAN provides connection and data exchange services through dedicated servers.
B/S is built on a wide area network. It does not need to be a dedicated network hardware environment, such as accessing the Internet over the phone and renting equipment. information management. it has a stronger adaptability than C/S. Generally, only the operating system and browser are available.
2. Different security requirements
C/s is generally oriented to relatively fixed user groups and has strong information security control capabilities. generally, the C/S structure is suitable for highly confidential information systems. some public information can be published through B/S.
B/S is built on a wide area network and has relatively weak security control capabilities. It is intended for unknown user groups.
3. Different program Architectures
The C/S program can focus more on processes, perform multi-level permission verification, and minimize the system running speed.
B/S's multiple considerations for security and access speed are based on the need for more optimization. higher requirements for B/S architecture than c/s is a development trend, from Ms. net series of BizTalk 2000 Exchange 2000 and so on, fully support the system built by network components. the JavaBean Component Technology pushed by Sun and IBM makes B/S more mature.
4. Different Software Reuse
The reusability of components is not as good as that of components under B/S requirements.
The multiple structures of B/S pairs require relatively independent components and can be reused relatively well. You can purchase a dining table instead of a stone table on the wall.
5. Different system maintenance
System maintenance is an important part of the software life cycle with high overhead.
Due to the integrity of the C/S program, it is necessary to make an overall investigation to solve the problems and system upgrades. Upgrading is difficult. It may be necessary to create a new system.
B/S components, which can be replaced individually to achieve seamless system upgrade. The system maintenance overhead is minimized. Users can download and install the components online to achieve the upgrade.
6. Different handling problems
The c/s program can fix the user surface and meet high security requirements in the same region. It is related to the operating system and should be the same system.
B/S is built on the Wide Area Network. It targets different user groups and is scattered across regions. This is what C/S cannot do. It has the least relationship with the operating system platform.
7. Different user interfaces
C/s is mostly built on Windows platforms, with limited performance methods and high requirements on programmers.
B/S is built on a browser, with richer and more vivid expressions to communicate with users, and most of the difficulties are reduced to reduce development costs.
8. Different information flows
C/S programs are generally typical centralized mechanical processing, with relatively low interaction.
B/S information flow to changeable, B-B B-C B-G and other information, flow changes, more like the transaction center.

Ii. Socket

On the network, an IP address and a port are collectively referred to as a socket. A pair of sockets can form a unique channel on the network.

3. Web application development cycle

1. Planning Web applications: requirement analysis, clarifying the required functions and objectives to be achieved;
2. design the application: what technology is used, what structure is used, and the dominant tone is ...;
3. Construct and test application components;
4. Implementation;
5. Production and maintenance.