Thinking about interview questions: A simple summary of the basic concepts of some containers in the web

Keywords: application server, Web server, Web container, JSP container, servlet container.

1. Application Server:

As an application server, it is required that commercial logic can be exposed to (expose) client applications through various protocols, including the HTTP protocol. The application uses this business logic just as you would call an object's method or procedure (a function in a language).

2.web Server (program/software):

WWW server or HTTP server. Provides web information browsing services. It only supports HTTP protocols, HTML document formats, and URLs. A program that provides services to the browser.

Current common Web servers:

Large: Microsoft IIS, IBM WebSphere, BEA WebLogic, Apache, Tomcat

Small: Nginx, micro_httpd, mini_httpd, thttpd, LIGHTTPD, shttpd

3.web Container:

A Web server that meets certain criteria is a Web container. is a Web server or application and server part, for example, Tomcat,weblogic, and so on, the implementation is Jsp,servlet;tomcat is the servlet and JSP running container.

Web container: Provides an environment, JSP container, and SERVLET container for the application component (Jsp,servlet) in which it is located. Enables Jsp,servlet to interact directly with the environment variable interfaces in the container without having to focus on other system issues. Implemented primarily by Web servers. For example: Tomcat,weblogic,websphere and so on. The interface provided by this container strictly complies with the Web application standard in the Java EE specification. Our web server, which adheres to the above criteria, is called the Web container in Java EE.

EJB container: Enterprise java bean container. It has the industry domain characteristic more. He provides various management functions for the EJB component that runs in it. As long as the EJB that satisfies the Java EE specification is placed in the container, it is immediately managed efficiently by the container. and the system-level services can be obtained through the existing interfaces. For example, mail service, transaction management.

The Web container and the EJB container are basically the same in principle, and the more difference is the isolated external environment. The Web container is more of a deal with HTTP-based requests. And the EJB container is not. It is more about dealing with databases and other services. But they are all interacting with the outside world to reduce the burden on the application. For example, the servlet does not care about the details of HTTP, directly referencing the environment variable session,request,response, EJB does not care about the database connection speed, various transaction control, directly by the container to complete.

4.serlvet Container :

Store maintenance and creation of servlet-related logic, the primary task is to manage the servlet's life cycle

5. At this stage, JSP containers, serlvet containers, web containers are basically synonymous.

Thinking about interview questions: A simple summary of the basic concepts of some containers in the web