Tutorial J2ee in PDF

What is Java EE?

For many early-stage J2EE developers, Java EE is equivalent to Enterprise JavaBeans (EJB). However, Java EE is much more than EJB. Java EE is a suite of API specifications, a distributed computing architecture, and definitions for packaging distributable components for deployment.

It is a collection of standardized components, containers, and services for creating and deploying distributed applications in a well-defined distributed computing architecture. Sun says Java Platform, Enterprise Edition 5 sets the standard for developing component-based, multi-tier enterprise applications. "As the name suggests, Java EE targets large-scale enterprise systems. Software that works at this level does not work on a single PC: it requires much more computing power and throughput than that. For this reason, the software must be partitioned into functional parts and deployed on the appropriate hardware platforms. This is the essence of distributed computing. Java EE provides a collection of standardized components that facilitate software deployment, standard interfaces that define the interconnection of different software modules, and standard services that define how different software modules communicate.

Develop distributed enterprise applications

The word enterprise has magical powers in computer programming circles. It can increase the price of a product by an order of magnitude and double the potential salary of an experienced consultant. Your application can be bug-free, and coded cleanly using all the latest techniques and tools, but is it ready for the business? What exactly is the magic ingredient that makes business development qualitatively different from ordinary development?

Enterprise applications (large-scale business applications) solve business problems. This usually involves the safe storage, retrieval and manipulation of company data: customer invoices, mortgage applications, flight reservations, and so on. They can have multiple user interfaces: a consumer web interface and a graphical user interface (GUI) application running on computers in branch offices, for example. Enterprise applications must address communication between remote systems, coordinate data across multiple stores, and ensure that the system always follows the rules established by the enterprise. If part of the system goes down, the company loses some of its ability to function and starts losing money. If the business grows, the app needs to grow with it. All this adds to what characterizes enterprise applications: robustness in the face of complexity.

Developing distributed applications that are scalable, robust, secure and maintainable and that run on distributed IT infrastructures is not a simple task. There are many critical things to consider such as security, database access, and transaction control. Security ensures that users are the ones they claim to be and can only access those parts of the application that they are allowed to access. Access to the database is also a fundamental component for your application to store and retrieve data. Transaction support is required to ensure the right data is updated at the right time.

That's why architectures based on Java EE are so convincing; Indeed, J2EE supports applications that are partitioned into multiple tiers (n-tier architecture). The hardware infrastructure at the system level is already in place through a set of containers, connectors and components based on already published specifications and standards. This means that applications written for Java EE will run on an unlimited number of implementations compatible with these standards.

What is the relationship between Java EE and J2SE

Java allows you to program desktop GUI applications that run on any operating system. In addition, Java EE provides a well-tuned interface with a set of libraries to develop more complex applications that deploy on large architectures and distributed systems.

Java EE does not replace Java 2 Standard Edition (J2SE). J2SE provides the essential linguistic framework on which Java EE is built. This is the kernel on which Java EE is based, Java EE consists of several layers, and J2SE is the base of this pyramid for each component of Ja

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