Resolve the differences between Web servers and application servers (1)

In layman's terms, Web servers send pages to allow browsers to browse. However, the application server provides the methods method that client applications can call ). Specifically, you can say that the Web server specifically processes HTTP request requests), but the application server uses many protocols to provide serves for applications) business logic ).

Let's take a closer look:

Web Server)

The Web server can parse handles) HTTP protocol. When the Web server receives an HTTP request), it returns an HTTP response (response), for example, sending back an HTML page. To process a request), the Web server can respond to response) a static page or image for page Jump redirect), or dynamically respond to dynamic response) to generate a delegate) for other programs such as CGI scripts, JSPJavaServer Pages) scripts, servlets, and ASPActive Server Pages, server-side) JavaScript, or some other server-side) technology. Regardless of their Translator's note: scripts), these server-side programs usually generate an HTML response) to allow browsers to browse.

You know, the Web server's proxy model delegation model) is very simple. When a request is sent to the Web server, it simply sends the request) to a program that can handle the request well. Note: server scripts ). The Web server only provides an environment that can execute server-side) Programs and return programs to respond to response), without exceeding the functional scope. Server-side) programs generally have functions such as transaction processing, database connectivity, and message messaging.

Although the Web server does not support transaction processing or database connection pools, it can configure employ) various strategies) to achieve fault tolerance failure) and scalability, such as load balancing ), cache ). Cluster features clustering-features) are often mistaken for only the proprietary features of application servers.

Application Server The Application Server)

According to our definition, as an application server, it uses various protocols, including HTTP, to expose business logic to expose) client applications. The Web server mainly processes HTML sent to the browser for browsing, and the application server provides a way to access the business logic for the client application to use. Applications use this business logic just like calling a method of an object or a function in a process language.

The client of the Application Server contains a graphical user interface GUI) may run on a PC, a Web server, or even other application servers. The information of traveling between the application server and its client is not limited to simple display tags. On the contrary, this information is the program logic ). It is precisely because this logic has obtained the form of takes) data and method call cballs) instead of static HTML, so the client can use this exposed business logic as desired.

In most cases, the application server exposes the business logic to the client application through the application interface API of the component), for example, based on J2EEJava 2 Platform, enterprise Edition) EJBEnterprise JavaBean of the application server. In addition, application servers can manage their own resources, such as gate-keeping duties) including security, transaction processing, and resource pool pooling ), and messaging ). Like Web servers, application servers are configured with a variety of scalable scalability) and fault-tolerant fault tolerance) technologies.