Java EE beginners to proficient problems that must be understood

j2ee| Beginners | Problem Java Architecture simple Introduction

background of the proposed Java EE

1, Enterprise-class application framework requirements

In many enterprise applications, such as database connectivity, mail services, transactions, and so on, are common enterprise requirements modules, which, if developed by developers, can lead to long development cycles and poor code reliability. So many large companies have developed their own general-purpose modular services. These service software series with Chen as the middleware.

2, in order to General must put forward the specification, otherwise could not reach the general

On the basis of the above requirements, many companies have developed their own middleware, but their communication with the user are different, which leads to users can not assemble the different middleware of various companies to serve themselves. thus creating bottlenecks. Then the concept of the standard was proposed. In fact, Java-EE is a series of standards based on java-based technology.

Note: The interpretation of middleware

Middleware is located between the operating system and higher level applications. His function is to isolate the application running environment from the operating system, so that the application developer does not have to worry about more system issues and is directly concerned about the application's ability to solve the problem. The concept of the container that we are talking about is one of the middleware.

　　 ii. explanation of relevant nouns

Containers: Role Web containers that act as middleware: provide an environment for the application component (Jsp,servlet) in which the jsp,servlet interacts directly with the environment variable interfaces in the container, without paying attention to other system issues. There are mainly Web servers to implement. For example: Tomcat,weblogic,websphere and so on. The interface provided by the container adheres strictly to the Web application standard in the Java EE specification. Our web server that adheres to the above standards is called the Web container in Java EE.

EJB container: Enterprise java bean container. More features of the industry area. He provides various management functions for the component EJB running in it. As long as the EJB that satisfies the Java-EE specification is placed in the container, it will be efficiently managed by the container immediately. and the system-level services can be obtained through out-of-the-box interfaces. such as mail services, transaction management.

Web containers and EJB containers are essentially the same in principle, with more distinction being isolated outside environments. Web containers are more about dealing with HTTP-based requests. And the EJB container is not. It's more about databases and other services. But they are both implementing interactions with the outside world to ease the burden on the application. For example, the servlet does not care about HTTP details, directly referencing the environment variable session,request,response on the line, EJB does not care about the database connection speed, various transaction control, directly by the container to complete.

RMI/IIOP: The remote method calls the/internet object to request the mediation Protocol, which they use primarily for the remote invocation of the service. For example, there is a remote computer running a program that provides stock Analysis services that we can invoke directly on the local computer. Of course, it is necessary to pass a certain specification in order to communicate between heterogeneous systems. RMI is Java-specific.

Jndi:java Naming directory service. The main features are providing a directory system that allows other applications to leave their own indexes on them to meet the ability to quickly find and locate distributed applications.

Jms:java Message Service. The main implementation of communication between the various applications. Includes point-to-point and broadcast.

Javamail:java Mail Service. Provides storage and transmission of messages. He is the core of the implementation of the mail function in Java programming. Exchange development packages in considerable Ms.

Jta:java transaction Services. Provides a variety of distributed transaction services. The application simply invokes the interface it provides. Jaf:java Security Certification Framework. Provide some framework for security control. Allow developers to implement their own personalized security control strategies through a variety of deployments and customizations.

EAI: Enterprise application integration. is a concept that involves a lot of technology. Java-EE technology is a good integration implementation.

　　 third, the superiority of the Java EE

1, based on Java technology, platform-independent performance of outstanding

2, open standards, many large companies have implemented the specification support of the application server. such as Bea, Ibm,oracle and so on.

3, to provide a very professional general software services.

4, provide a good enterprise-class application framework for rapid high-quality development lay the foundation.

　　 iv. Status Quo

Java EE is a set of enterprise application specification developed by Sun Company. Now the highest version is 1.4. The application server that supports Java EE has IBM WEBSPHERE application Server,bea WEBLOGIC server,jboss,oracle application Server,sun one application SERVER, and so on.