Pang Yan
---- As Internet and businesses have gradually evolved into a standard for client-computing standards, the Internet and businesses have gradually evolved into a standard for client-computing, which has driven the development of centralized business logic and popularization of e-commerce. In server-side, CGI (CommON Gateway Interface, public gateway interface), NSAPI (Netscape Server API), and ISAPI (Internet Server API) and other multi-popular models have become increasing the workload of programming and maintenance.
---- 5 years ago, Sun's Java software shocked the entire Web world with its cross-platform application development and configuration. In the past few years, Java technology has developed from a website tool to the end-to-end Java 2 platform for a series of systems such as smart cards, small consumer equipment to large data center servers, which makes software developers, service providers and equipment manufacturers. It is easier to seize market opportunities.
---- Currently, the Java 2 platform has 3 versions, which is a Java 2 platform for small devices and smart cards Micro version (Java 2 Platform Micro Edition, Java 2), Java 2 Platform Standard Edition for desktop systems (Java 2 Platform Standard Edition, J2SE, suitable for Java 2 Platform Enterprise Edition (Java 2 Platform Enterprise Edition, J2EE) for creating server applications and services. Today we have to discuss J2EE.
J2EE framework
---- J2EE is an architecture using Java 2 platform to simplify complex issues related to multi-level enterprise solutions. The basis of J2EE technology is the standard version of the core Java platform or Java 2 platform. J2EE not only consolidates many of the advantages in the standard version, such as "writing once, run" characteristics, easy to access the JDBC API, CORBA technology, and capable of accessing the database. Safety mode for protecting data in the Internet application, etc., and also provides comprehensive support for EJB (Enterprise JavaBeans, Java Server Pages), and XML technology.
---- Sun has added a set of core enterprise application programming interfaces in the Enterprise Edition, while all of these interfaces are standard modular components. J2EE technology also provides a complete set of business services to these components. By automating how much time consumption in application development, it provides users with a widely compatible enterprise solution without complex programming. platform. With this advantage, you can easily develop high-quality applications that use applications, which can also greatly reduce product development time, cost and risk.
---- J2EE uses EJB Server as a deployment environment of business components, providing all services required by components in the distributed computing environment in EJB Server, such as management of component lifecycles, management of database connections, support for distributed transactions , Component naming services, etc. Some enterprise-level EJB Server, such as Sybase's EAS 3.6 (Enterprise Application Server 3.6) also provides a cluster technology that supports high availability and high performance, failed automatic transfer and recovery, automatic balance of application load. EJB components for realizing business logic can run more efficiently in the application server, support multiple client access, HTTP clients can first request Java Servlet or JSP running on Web Server, embed Java's code in JSP Call the EJB running in EJB Server to implement business logic; other clients, can directly access components running in EJB Server via IIOP. Advantages of J2EE
---- J2EE provides an enterprise-class computing model and an operating environment for developing and deploying multi-layer architectural applications (shown in J2EE). It provides high availability, security, scalability, and reliability to be deployed by providing various services necessary for the enterprise computing environment. Its superiority is that the calculation platform supports the Java language, making the application based on J2EE standards can be transplanted across platforms; Java language is very safe and strict, which enables developers to write very reliable code; J2EE provides enterprise calculations All services needed, and more easily; Most criteria in J2EE define interfaces, such as JAVA Naming and Directory Interface, JDBC, Java Mail, etc., so you can cooperate with many manufacturers, easy to support; J2EE Established a wide and universal standard, greatly simplifies the application development and transplantation process.
---- In summary, the advantage of the J2EE architecture is:
Java servlets and JSPs must be compiled as Java Class as a servlet, so performing performance will be significantly improved. Java Servlet and JSP can be used in Java to program, you can complete a lot of simple business logic, especially JSP, you can write HTML directly, so you simplify the output of the page, so that the scripting language is easy to use. Complex business logic is deployed in EJB Server in the form of a component. Since EJB Server provides a variety of component transaction services, making the system more capable of paying a large number of concurrent users and management complex transaction logic. The integrated component naming service in EJB Server allows the component location to transparent, simplifies the maintenance of components deployment and client applications. The development process is easy to divide and can be responsible for writing components, others are assembled. The J2EE platform fully supports and implements XML. This powerful combination allows XML to have cross-platform compatibility, and even tools for syntax checking and debugging XML code can also be independent of the platform. J2EE technology and XML technology are the yin and yang poles developed by enterprises, as XMLs can implement independent platform data, while J2EE platforms can implement independent platform-based solutions. XML can express data by transplantation, so addability to Java technology.
Core API and Components
---- People generally need a computing platform that provides general service to solve the problem of application development and deployment and transplantation. This is the same as things encountered in our lives, for example, when you move to a new house, suddenly found that all power sockets are different from the original house, the voltage is different, all the electrical appliances must be re-purchased! Is this a very troublesome thing? Therefore, the advantage of J2EE is obvious, as if developers are expected, J2EE provides the core API provided by most companies, and developers don't have to follow the solutions of various products, and do not need to learn a variety of various products. Product unique API interface, everything is getting simpler. This is why J2EE is generally concerned. The core API provided by J2EE is shown in Schedule. ---- As a complete enterprise computing environment, the J2EE platform also includes many components, such as Platform Specification, Reference Examples, Compatibility Test Suite, and J2EE Bluemap (J2EE Blueprints) )Wait.
---- Among them, the platform specification lists all the necessary elements of the platform, as well as policies that must be followed by effective J2EE technology implementation, explain the API provided with various operating system versions of the J2EE platform, but also defined A stable and flexible method of executing a J2EE platform. Reference examples are a correct example of the J2EE platform syntax, which is the prototype of the manufacturer for retest. The compatibility test kit is designed to ensure that different J2EE technology implementation can run the same application. The J2EE blueprint provides an architecture that includes documents and instance kits for implementing J2EE-based multi-layer applications, and some simplifying the establishment of access and managing data and applications required for various enterprise resources. Engineering such a complex work.
Support for J2EE
---- J2EE has become a factual standard for developers to create e-commerce applications. It is to recognize the J2EE platform as an extensible, full-featured platform that extends key enterprise applications to any web browser and can be suitable for a variety of different Internet data streams, which can be connected to almost any kind of tradition. Databases and solutions enable business manager to reduce the cost and complexity of the development of networking applications based on the products and technological development and deployment of many companies, many manufacturers represent the J2EE Support and J2EE technology as a safe and stable end-to-end platform for large BTOB markets and massive transactions. There have been many manufacturers to obtain Sun's license, such as Bea System, Sybase, Oracle, and Fujitsu, etc. Sun will also introduce J2EE applicable to Linux. Undoubtedly, J2EE outlines a blueprint for enterprises with stronger scalability, openness, security and easy use.
