6、 Common middleware
1、Tomcat
Tomcat is a core project of the Jakarta project of the Apache Software Foundation, which is jointly developed by Apache, Sun and other companies and individuals. Because of its advanced technology, stable performance and free of charge, Tomcat is deeply loved by java lovers and recognized by some software developers. It has become a popular Java Web application server (servlet container). In fact, Tomcat is an extension of Apache server, but it runs independently. So when you run Tomcat, it actually runs independently of Apache. Tomcat server is a free open source Web application server, which is a lightweight application server. It is widely used in small and medium-sized systems and where there are few concurrent users. It is the first choice for developing and debugging JSP programs. Tomcat uses port 8080 by default
2、WebLogic
WebLogic is an application server produced by Oracle Corporation of the United States. Specifically, it is a middleware based on JAVAEE architecture. WebLogic is a Java application server used to develop, integrate, deploy and manage large-scale distributed Web applications, network applications and database applications. The dynamic functions of Java and the security of Java Enterprise standards are introduced into the development, integration, deployment and management of large network applications. The default port of Weblogic is 7001.
3、Jboss
Jboss is an open source application server based on Java EE. It is not only a servlet container, but also an EJB container, which is welcomed by enterprise developers, thus making up for the defect that Tomcat is only a servlet container. JBoss is a container and server for managing EJBs. However, JBoss core services do not include WEB containers that support servlets/JSPs. They are generally used with Tomcat or Jetty. The default port number of Jboss is 8080.

4、Jetty
Jetty is an open source servlet container that provides a running environment for Java based web containers, such as JSPs and servlets. Jetty is written using JAVA, and its API is published in the form of a set of JAR packages. Developers can instantiate the Jetty container into an object, which can quickly provide network and web connectivity for some stand alone Java applications.
5、Webshere
WebShere is IBM’s software platform. It includes the entire middleware infrastructure, such as servers, services, and tools, needed to write, run, and monitor 24×7, industrial strength, on-demand Web applications and cross platform, cross product solutions. WebSphere provides reliable, flexible, and robust software. WebSphere is a modular platform based on open standards supported by the industry. Existing assets can be plugged into WebSphere through trusted and persistent interfaces, and the environment can continue to be extended. WebSphere can run on many platforms, including Intel, Linux, and z/OS. The default port number of Webshare is 9080.
6、Glasshfish
GlassFish is a robust, commercially compatible application server with product quality, which can be used for development, deployment and redistribution for free. Developers can get the source code for free, and they can also make changes to the code.