Foreword
J2EE is undoubtedly one of the most popular topics today, its full name is Java 2 Platform Enterprise Edition. It provides high availability, security, scalability, and reliability, plus multi-layer applications deployed on the J2EE platform, plus major manufacturers such as IBM, Oracle, BEA Support, it has become unlatted to become an industrial standard for enterprise-level development.
But many of the J2EE huge hustlers often make the developers who want to master this technology, this paper tries to combine the author's many years of development experience, with a brief language to make an entry-level introduction to J2EE (side focus EJB technology enables more developers to easily add J2EE developers ranks.
J2EE Technology Overview
J2EE includes JSP, Servlet, EJB (Enterprise JavaBean), RMI (Java Remote Method Call), JDI (Java Name, Directory Interface), JDBC (Java Database Connection), JMS (Java Message Service , JavaMail (Java mail), etc., where EJB technology is undoubtedly the most important part of J2EE. It itself uses other technologies of J2EE, and it is our focus of this.
Typically, the enterprise application system implemented by J2EE is shown in Figure 1-1. Business logic is often implemented in EJB, and the client issues a request to the Java Servlet or JSP running on the web server, then forward the request, run in EJB Server EJB, then EJB access to the database and returns the information to the client, which is also very good to reflect the idea of MVC (model, trying, control).
Figure 1-1
Applications are usually deployed in a file called Enterprise Archive, the suffix of this file is .ser, so it can be referred to as an EAR file, which is usually shown in Figure 1-2.
To Be Continue ...
To Be Continue ...
