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This article introduces how the Web server is included by the application server, the content is very detailed, interested friends can refer to, hope to be helpful to you.

In the multi-tier architecture of traditional Web applications

The system generally includes a load balancer.

Web server, application server and other back-end services

Among them, Web server and application server

Is often seen as a whole.

But in fact, in terms of working principle,

There is still a certain distinction between the two.

Web Server

The basic function of Web server is to provide Web information browsing service. It supports HTTP protocol, HTML document format and URL, specializes in handling HTTP requests (request), and can cooperate with the web browser on the client side. What it provides is an environment that can execute a server-side (server-side) program and return a response (response) generated by the program.

The steps taken by the Web server on web page processing are as follows:

1. Web browsers issue Web page requests to a specific server

2. After receiving the web page request, the Web server will send the request to the application server and pass it to the program that processes the request to find the requested web page.

3. The Web server receives the requested web page content from the application server and returns the result to the Web browser on the client side for display.

The Application Server

The function of the application server (application server for short) is to enable multiple users to use the application at the same time. It provides methods (methods) that client applications can call (call), and provides (serves) business logic (business logic) for applications through many protocols.

If the Web server mainly deals with sending HTML to the browser for browsing, the application server provides access to business logic for use by client applications. An application uses this business logic like calling a method of an object (or a function in a procedural language). For example, the navigation, data storage, security authentication and control process involved in the user center, settlement center and payment center all need to rely on the application server to respond.

In the past, the functional difference between the two was obvious.

And now, in most cases,

People are used to classifying Web servers as

A subset of the application server

Because with the continuous addition of their respective functional items

The line between them has long been blurred.

We know that the content of web pages is both static and dynamic. For static content, the Web server can send the result back to the browser directly. For dynamic content, it usually needs to be processed by the application server first, and the result is returned by the application server. In the early days, due to the limitations of HTTP 1.0 protocol, most of the page content and picture services provided by web services were static. Later, with the addition of CGI functionality, it means that a process can be started for each web request to generate dynamic content. For example, the most commonly used Web server in .NET is IIS, because IIS can interpret and process ASP and ASP.NET, two Microsoft dynamic web scripting languages.

Although the Web server does not support transaction processing or database connection pooling, as the HTTP protocol becomes more mature, the Web server has also become more complex, with additional features such as caching, security, and session management, which can handle higher load, more concurrency, and pass the XML payload (payload) to the server. Equip yourself with the ability to process data and respond (response) (as long as you don't need an application server to handle the logic).

Just like the Web server, the application server is equipped with a variety of fault tolerance (fault tolerance) and extensible (scalability) technologies, and the traditional application server begins to embed the functions that originally belong to the Web server, such as HTTP communication. Most application servers now actually contain a Web server, which means that the Web server can be treated as a subset of the application server. However, in the architecture of some complex websites, we still recommend that the two should be configured separately. After all, the necessary separation of some functions helps to improve the overall performance of the system and leaves room for maintenance and upgrade.

About how the Web server is included by the application server to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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