Java Web application development overview

 

Java Web application development overview

1. program development architecture

There are many network program development architectures, among which the most widely used network application development architecture is two, one is based on Browser/Server B/S structure, the other is based on the C/S structure of the Client/Server. With the following content, you can master the technologies and web development processes required by web development on the server and browser respectively.

1) C/S architecture

C/s is the abbreviation of Client/Server, that is, the Client/Server structure. A server usually uses a high-performance PC or workstation and a large database system (such as oracle or SQL Server). A dedicated client software must be installed on the client. This structure can take full advantage of the advantages of both ends of the hardware environment, and allocate tasks to the client and server reasonably, thus reducing the communication overhead of the system.

2) B/S architecture Introduction

B/S is the abbreviation of Browser/Server, that is, the Browser/Server structure. In this structure, the client does not need to develop any user interface, but uses browsers such as IE, Firefox, to send requests to the Web server through a Web browser, which is processed by the Web server, the processing results are sent back to the client step by step. This structure uses sophisticated and universal browser technology to implement powerful functions that originally required complex specialized software, thus saving development costs. It is a brand new software architecture.

3) Comparison of the two architectures

(1) Development and maintenance costs

The development and maintenance costs of the C/S structure are higher than those of B/S. When the C/S structure is used, the system maintainer must uninstall the original software on the client, install the new version, and configure it. For B/S-Structured Software, the system maintainer only needs to upgrade the server software to the latest version. For other clients, you only need to log on to the system again to use the latest version of software.

(2) Client Load

The C/S client is not only responsible for interaction with users, but also needs to request the server through the network to process the database, workbooks, documents, and other information. The client in the B/S structure handed over the transaction processing logic to the server for processing. This reduces the client load, but at the same time, the server load at home.

(3) Security

The C/S structure is suitable for dedicated systems. You can use strict management and distribution software to ensure system security. Such software is relatively secure. The software with B/S structure is relatively less secure because it is used by a large number of users and is not fixed.

2. How web applications work

Web applications can be divided into static websites and dynamic websites. Static websites are written in HTML. users use browsers to request web pages on the server over HTTP. After the Web server on the server processes the received user requests, the browser sent to the client is displayed to the user.

Dynamic websites are usually written in HTML and dynamic scripting languages (such as JSP, ASP, and PHP) and deployed on Web servers, the Web server processes dynamic script code, converts it to HTML code that can be parsed by the browser, returns it to the client browser, and displays it to the user.

3. Web Application Technology

When developing Web applications, you usually need two technologies: Application client and server. The client is used to display information content, and the server is used to process business logic and interact with databases.

1) client application technology

Common Client technologies include HTML, CSS, Flash, and client script.

L HTML language: the basis of Client technology. It is used to display webpage information, which is interpreted and executed by the browser. It does not need to be compiled and is case-insensitive.

L CSS: style sheet technology, or Cascading Style Sheet ). It is used to control the page layout, Font, color, Beijing, and other effects more accurately. CSS greatly improves developers' control over information display formats, especially in the popular CSS + Div layout websites.

L FLASH: Flash is an interactive animation production technology that can contain animations, audios, videos, and applications. Moreover, Flash files are small and suitable for Web applications.

L client script technology: it refers to the program code embedded into the web page. The code is an explanatory language, and the browser can interpret the client script. The scripting language can be used to control page elements programmatically, thereby increasing page flexibility. Common Client scripting languages include JavaScript and VBScript. Javascript is an important part of Ajax.

2) server-side Application Technology

Common server technologies include CGI, ASP, PHP, ASP. NET, and JSP.

L CGI: Common gatewayinterface (CGI), which is the first technology used to create dynamic web pages, enables interactions between browsers and servers. It allows you to write appropriate CGI programs in different languages, which are run on Web servers. Because the server executes the specified CGI program in process units, this technical method is difficult and inefficient. Supported languages include C/C ++, Java, and Perl.

L asp: Active Server Page is a widely used technology for developing dynamic websites. Dynamic Content is generated by embedding VBSCRIPT or Javascript script language in the page code. ASP can call the COM component that exists in the background to complete the process. The COM component infinitely expands ASP capabilities. Because of this, the local COM component is mainly used in the Windows NT platform, so the problems in windows will be mapped to it.

L PHP: personal home page. The syntax is similar to C. It is an open-source Web Server scripting language. complex operations can be encapsulated into functions or classes. Many defined functions, such as standard database interfaces, are provided in PHP to facilitate database connection and improve scalability. PHP is widely used in Unix/Linux platforms and is the most secure dynamic web page technology so far.

L asp. NET: the technology for establishing dynamic web applications. As part of the. NET Framework, ASP. NET applications can be written in any. Net-compatible language to achieve better performance than the scripting language. Web forms allows you to create powerful forms based on Web pages. When creating a page, you can use the ASP. NET Server Control to create common UI elements and program them to complete general tasks. These controls allow developers to quickly create web forms using built-in reusable components and custom components, which simplifies code.

L JSP: Java Server Page, which follows the powerful Java API functions. The HTML code on the JSP page is used to display static content, the Java code and JSP tag embedded in the page are used to generate dynamic content. JSP allows the program to compile its own tag library to fulfill the specific requirements of the application. JSP can be pre-compiled, improving the program running speed. In addition, JSP-developed applications also have the "one-time compilation, ready to use" feature.