What is J2EE (1) and J2EE (1)

What is J2EE (1) and J2EE (1)
1. J2EE Concept

Currently, the Java 2 Platform has three versions. These are the Micro version of Java 2 Platform (Java 2 Platform Micro Edition, j2_based) applicable to small devices and smart cards) java 2 Platform Standard Edition (J2SE) for desktop systems and Java 2 Platform Enterprise Edition (Java 2 Platform Enterprise Edition, j2EE ).

J2EE is an architecture that uses the Java 2 platform to simplify the development, deployment, and management of enterprise solutions. The foundation of J2EE technology is the Standard Edition of the core Java platform or Java 2 platform. J2EE not only consolidates many advantages of the Standard Edition, for example, the features of "writing once and running anywhere", jdbc api for convenient database access, and CORBA technology, as well as the security mode that can protect data in Internet applications, etc, it also provides comprehensive support for EJB (Enterprise JavaBeans), Java Servlets APIs, JSP (Java Server Pages), and XML technologies. The ultimate goal is to become an architecture that can greatly shorten the time to market for enterprise developers.

The J2EE architecture provides an intermediate layer integration framework to meet the needs of applications that require high availability, high reliability, and scalability without too much cost. By providing a unified development platform, J2EE reduces the cost and complexity of developing multi-tier applications. It also provides strong support for existing application integration and fully supports Enterprise JavaBeans, A good wizard supports packaging and deploying applications, adding directory support, enhancing the security mechanism and improving performance.

PS: 2EE is called Java2 Platform Enterprise Edition. "The J2EE platform is essentially a distributed server application design environment-a Java environment, which provides a basic runtime framework Environment for the host application and a Java extension API for creating the application."

2. Java and J2EE

With the rapid development of Internet networks, Internet-based enterprise applications require that software platforms be open, distributed, and platform independent. As a result, technologies such as RPC/COM/CORBA have emerged one after another, but these technologies have many shortcomings and limitations in practical application. Their specific protocols are difficult to pass through the firewall, so they are not suitable for application development on the Web. To further develop Web-based applications, Sun
ONE (Open Net Environment Development Network Environment) and Microsoft's. NET and other Web Service technical systems.

Sun
The ONE architecture is centered on the Java language, including J2SE/J2EE/J2EE and a series of standards, technologies and protocols. It includes Sun's unique iPlanet Software Series, including popular LDAP directory server software on the market, and Forte
For Java-a software tool that allows you to write the Java language in any environment. We can easily obtain and use Java from the Internet for free.
Integrate the development environment, Java database, Application Server, and other products, as well as their source code. Sun
ONE is closer to or can meet the distributed, development, and platform independence requirements of the smart Web service providers on the Internet.

With the continuous development of Java technology, Java 2 Enterprise
Edition), J2SE (Java 2 Standard) for general PC applications
Edition) and Java 2 Micro Edition for embedded devices and consumer appliances. Sun
ONE's core Java applications-J2SE, J2EE, and j2s.

3. Advantages of J2EE

J2EE provides a good mechanism for building a business system with scalability, flexibility, and maintainability.

• Retain existing IT assets

As enterprises must adapt to new business needs, it is important to use existing investment in enterprise information systems, rather than re-developing a full solution. In this way, a server-side platform mechanism built on an existing system is required by the company in a gradual (instead of radical, totally no) manner. The J2EE architecture can take full advantage of users' original investments, such as BEA Tuxedo, ibm cics, IBM Encina, Inprise VisiBroker, and Netscape Application Server used by some companies. This may be because J2EE has extensive industry support and the participation of some important vendors in the 'Enterprise compute' field. Every supplier provides existing customers with a way to upgrade to the portable J2EE field without having to discard existing investments. Because J2EE platform-based products can run on almost any operating system or hardware configuration, existing operating systems and hardware can also be retained for use.

• Efficient Development

J2EE allows companies to deliver some common and cumbersome server tasks to middleware vendors. In this way, developers can focus on how to create business logic and shorten the development time accordingly. Advanced middleware vendors provide the following complex middleware services:
Status Management Service-allows developers to write less code without having to worry about how to manage the status so that they can complete program development more quickly.
Continuity service-allows developers to write applications without coding the data access logic and generate lightweight and database-independent applications, which are easier to develop and maintain.
Distributed Shared data object CACHE service-enables developers to compile high-performance systems, greatly improving the overall deployment scalability.

• Supports heterogeneous environments:

J2EE can develop portable programs deployed in heterogeneous environments. J2EE-based applications do not rely on any specific operating system, middleware, or hardware. Therefore, a reasonably designed J2EE-based program can be deployed on various platforms only once for development. This is critical in a typical heterogeneous enterprise computing environment. The J2EE standard also allows customers to order third-party ready-made components compatible with J2EE and deploy them in heterogeneous environments, saving the cost required to develop the entire solution by themselves.

• Scalability

Enterprises must select a server-side platform that provides excellent scalability to meet a large number of new customers who operate their systems commercially. Applications based on the J2EE platform can be deployed on various operating systems. For example, it can be deployed to high-end UNIX and mainframe systems, which can support 64-256 processors on a single machine. (This is beyond the reach of NT servers) suppliers in the J2EE field provide more extensive Load Balancing policies. Eliminate system bottlenecks and allow integrated deployment of multiple servers. This deployment can reach thousands of processors, achieving highly scalable systems to meet the needs of future commercial applications.

• Stable availability

A server platform must be able to run around the clock to meet the needs of customers and partners. Because the INTERNET is global and ubiquitous, even if it is stopped at night, it may cause serious losses. If an unexpected shutdown occurs, there will be disastrous consequences. J2EE is deployed in a reliable operating environment. They support long-term availability. Some J2EE instances are deployed in WINDOWS, and customers can choose Operating Systems with better performance, such as Sun Solaris and ibm OS/390. The most robust operating system can achieve 99.999% availability or only 5 minutes of downtime per year. This is an ideal choice for real-time commercial systems.

Summary

J2EE is a set of technical architecture completely different from traditional application development. It contains many components, which can simplify and standardize the development and deployment of application systems, thereby enhancing portability, security, and reuse value.

The core of J2EE is a set of technical specifications and guidelines, which contain various components, service architecture and technical layers and have common standards and specifications, so that various platforms that follow the J2EE architecture can, there is good compatibility to solve the problem of incompatibility between the information products used by the enterprise backend in the past, making it difficult for the enterprise to communicate internally or externally.
This article briefly introduces some basic knowledge about J2EE. Next time, we will continue to learn about the J2EE architecture and API. Maybe we are not very familiar with these things now, but as we learn more deeply, these things will understand

.