What is Web? What is a Web server? What is an application server?

1, what is the Web?

　　In short, the Web is a Web site that is based on the HTTP protocol and is accessed by a browser. The most commonly used meaning at the moment is the section on intenet that is related to HTML. In other words, the network resources currently accessed through non-browser on intenet are not called Web. Web page refers to a Web page within a Web site. We often say that the WWW (World Wide web) is the content of this concept.

and the Internet (Internet) is a larger concept, the Internet is not only the web, there are FTP, P2p,email, or apps and other different ways of Internet applications. The web is just one of the most extensive. The Internet is more conceptual than the Web. "The web is dead on the internet" means that the importance of traditional Web sites may be reduced and that new Internet services may replace their importance. Although purely from the traffic, the Web is not the largest Internet application. But because the subject is text (or hypertext hypertext), the traffic overhead itself is much smaller than other applications such as video. The web may still be the most important Internet carrier.

2. What is a Web server? What is the difference between a Web server and an application server?

Strictly, the Web server is only responsible for processing the HTTP protocol, only the content of the static page can be sent. Dynamic content such as jsp,asp,php needs to be handled by other programs such as CGI, FastCGI, ISAPI, and other interfaces. This other program is the application server.

(1) Web server is designed to provide HTTP content, the application server can also provide HTTP content, but not limited to HTTP, it can also provide other protocol support, such as RMI/RPC.

(2) Web servers are primarily designed to provide static content, but most Web servers have plug-ins to support scripting languages, such as Perl, PHP, ASP, JSP, and so on, which can generate dynamic HTTP content.

(3) Most application servers make the Web server an integral part of it, which means that the application server can do what any Web server can do. In addition, the application server has components and features to support application-level services such as connection pooling, object pooling, transactional support, messaging services, and so on.

(4) Because the Web server is ideal for providing static content, and the application server is suitable for dynamic content, most production environments have a reverse proxy for the Web server acting as the application server. This means that when a page is requested, the Web server interprets the request by providing static content (example/static HTML), and it also uses some sort of filtering technology (primarily the extension of the request resource) to identify the dynamic content request and transparently forward it to the application server.

Non-rigorous summary: reception (Web server) with real value service (Application server).

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Links: https://www.zhihu.com/question/19860216/answer/13176861
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What is Web? What is a Web server? What is an application server?