Introduction to Java EE 1

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What is the Java EE standard:

Standard for developing enterprise applications based on the Java language Platform 2.0
Introduction
Java EE (that is, 2 Platform Enterprise Edition) is a common middleware technology launched by Sun to launch a number of industry vendors. From CORBA to IDL to message-oriented systems, middleware technology has come a long way, nowadays, as a milestone in the history of middleware technology, Java EE is being more and more widely regarded and adopted by the industry.
Java EE, on the one hand, has a large set of standard system and several different versions, on the other hand, because the market application server variety of applications, the terminology used by developers are not the same, so, around the Java EE, often have a lot of people misunderstood place. This article will delve into what the Java EE is, and what it can do.
What is Java EE.
Before trying to give a clear definition of EE, we first have to understand that the Java EE is not simply a language, a tool, or a set of services.
· J2ee--java 2 Platform Enterprise Edition
Simply put, Java EE is a standard middleware architecture designed to simplify and standardize the development and deployment of multi-tier distributed enterprise Application Systems. The implementation of Java EE scheme can significantly improve the portability, security, scalability, load balancing and reusability of the system.
Before the advent of Java EE Technology, several major middleware developers of the products of each of the array, lack of compatibility between each other, portability is poor, it is difficult to achieve interoperability, there is no universally recognized industry standards. The appearance of Java-EE indicates that the middleware technology is gradually maturing after years of continuous exploration and experience.
The core of Java EE is a set of specifications and guidelines that define a standard platform for developing multi-tier distributed enterprise Application systems using the Java language. Developers develop enterprise-class applications on the basis of these specifications and guidelines while ensuring compatibility between the different Java EE platforms by the Java EE vendor. Because of the good compatibility between various Java-EE platforms based on specification, the Java application system can be deployed on different application servers without or requiring a small amount of code modification.
· Java EE Viewpoint
Here we will examine the Java EE from a few different sides, hoping that the reader can have a more comprehensive and clear impression of the Java EE.
(1) Java EE: Multilayer, distributed middleware syntax
Using multilayer Distributed Application model, Java EE divides application development into different layers and defines components on each layer. Each application component is distributed on the same or different server based on the layer they are in, and it is composed of a multi-layer distributed system based on the component. Typical Java EE four-tier structure includes customer layer, presentation logic layer (Web layer), Business logic Layer and enterprise Information System layer.
With Java EE, the development of distributed system becomes simpler and the speed of deployment can be speeded up. The distribution of the Java EE component is independent of the server environment, and all resources are accessible through the distributed directory. This means that developers no longer need to expend energy on the distribution of components and resources, allowing more time to focus on the implementation of business logic and improve development efficiency.
(2) Java EE: Enterprise-Class application system development platform
Java EE itself is a standard, a standard platform for the development of enterprise distributed applications. The implementation of Java EE, however, is specific to the performance of specific Web server products such as BEA Web logic or IBM Web sphere. The enterprise application system developed using the Java EE application-programming model can be deployed on a compatible Java EE application Server produced by different manufacturers.
At present, the market based on Java-EE Web Server A wide variety of performance characteristics are different, each manufacturer's products have carefully designed unique. Regardless of the product personality, all Java EE application servers provide a common foundation for the development and deployment of enterprise-class application systems.
(3) Java EE: The model of electronic application development
Java EE applications can easily be posted on handheld devices such as web, handheld or mobile phones. In other words, application components can be easily implemented electronically. The Java EE application-programming model ensures that the business logic and back-end systems remain unchanged in the process of porting the components to different types of clients.
In addition, the other main advantages of Java EE platform are: Automatic load balancing, scalability, fault tolerance and troubleshooting features. Components deployed in the Java environment will automatically get the above features without adding additional code overhead.
All of these features are especially important for businesses that need to build 24x7 web portals.
(4) widely used standards in J2ee:web application server
It can be said that Java EE is the first to obtain the industry widely recognized and adopted the middleware standards. At present, almost all first-class Web application servers, such as Bea's Web logic, IBM's Web sphere, HP Application server, Sun's iplanet and Macromedia JRun, are all based on Java EE. To date, no other standards have been supported by so many middleware vendors.
And, with Java EE, the application development of the enterprise is less dependent on a particular developer or application service provider. Application components can be deployed on different application servers as long as they conform to the Java EE specification. To ensure compatibility and consistency of Java application servers for different vendors, Sun has released the Java EE Compatibility Test package.
· What exactly is the Java EE?
So far, we can try to sum up the Java EE with a word, that is: Java EE is a middleware infrastructure, with it, developers only need to focus on writing code to express the business logic and presentation logic of enterprise applications, as well as other system issues, such as memory management, multithreading, resource distribution and garbage collection, will be automatically completed by the Java EE.