Conceptual understanding of containers

Conceptual understanding of various containers

1. Container

The specific implementation of the service invocation specification, however, is a program in which the responsibility of the container differs depending on the service invocation specification that is executed, such as servlet container only to implement the Servlet 2.3 specification.

such as EJB containers (more with databases, other services), IOC containers, servlet containers

2.Web Container (more dealing with HTTP requests)

The main management of the servlet's establishment, lifecycle, JSP support,

The Web container is actually a Java runtime (Runtime) that provides an implementation of the Java Servlet API and simplifies JSP Web pages. The WEB container is responsible for initializing, invoking, and managing the lifetime of the Java Servlet and JavaServer Page. Examples of web containers are: Tomcat, Resin, WebLogic, and so on, without which the Web application cannot connect to a real network service

3.Web Server

However, the container of the Web container, such as Tomcat can be said to be a Web container, you can also say a Web server, or a servlet container (it implements the specification of the servlet).

This concept is broader, in addition to the functionality of the Web container, you can have some other features of Web applications, such as WebLogic and WebSphere, to implement container-managed transactions, the more accurate concept is called the Web application server

Comprehensive:

According to the breadth of the concept comparison:

servlet container <web Container <web server <web Application Server

(1) servlet container: But it's a program that manages the servlet lifecycle

(2) Web container: Primarily used to run Web applications (can contain multiple applications)

(3) Web server: The Web container's normal operation is dependent on the Web server to work properly on the Web server

(4) Web application Server: In addition to the functionality of the Web server, there are other features of the Web application, such as management transactions, support for clustering, replication through in-memory session state, enhanced availability and scalability of the deployment architecture, and good support for clustering, which can be done simply by adding machines, can easily improve the load-carrying capacity of the site, in terms of parsing capabilities, improve the throughput of HTML;

For example, Tomcat (/resin) for Web application execution, it is the Web container, for the deployment of Web applications, it is a Web server, many concepts are often confused, a bit of mutual infiltration and slightly different.

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