In this paper, five aspects of J2EE have been more comprehensive introduction. Speaking from the concept of J2EE, to its advantage, to the typical four-J2EE model, and its frame structure, and finally J2EE are 13 kinds of core technology, a brief introduction. This article on J2EE categories of services, components, levels, and containers, API has done a more detailed introduction, I believe after reading this article, readers J2EE will have a clearer understanding.
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API with the core J2EE components
J2EE platform consists of a set of services (Services), Application Programming Interface (APIs) and protocol composition, its Web-based multi-storey development will provide a functional support for J2EE in the following 13 kinds of technical specifications for a simple description (space is limited here only for easy description):
- JDBC (Java Database Connectivity): JDBC API to access different database provides a unified way, such as ODBC, like, JDBC developer shielding the details of a number of questions, another, JDCB access to the database also has a platform-independent nature.
- JNDI (Java Name and Directory Interface): JNDI API was used to perform name and directory services. It provides a consistent model to access and operation of enterprise-level resources such as DNS and LDAP, local file system, or application server object.
- EJB (Enterprise JavaBean): J2EE technical reason why a certain body to win one of the reasons for the extensive attention is the EJB. They offer a framework to develop and implement distributed business logic, which is significantly simplified with the scalability and highly complex enterprise-class applications. EJB specification defines how the EJB components when the container with their interaction. Container is responsible for providing public services such as directory services, transaction management, security, resource pooling and fault tolerance. But here it is worth noting that, EJB is not the only way to achieve J2EE. It is precisely because of the openness of J2EE, making some companies can and EJB in a parallel manner to achieve the same purpose.
- RMI (Remote Method Invoke): As its name, as indicated, RMI protocol method calls on remote object. It uses a serialization in the client and server to transfer data. RMI is an EJB to use a more bottom protocol.
- Java IDL / CORBA: At Java IDL's support, developers can be integrated with Java and CORBA. They can create Java objects and CORBA ORB can start, or they can also create Java category and as and other ORB of the CORBA object to start with the customer. The latter approach provides another kind of way, which Java can be used to your new application and old systems.
- JSP (Java Server Pages): JSP page from the HTML code and embedded in one of the components of the Java code. Server of the page requested by the client after treatment of these Java code, then the generated HTML page back to the client browser.
- Java Servlet: Servlet is a small Java program that extends the Web server functionality. As a server-side applications, when beginning the implementation of the request, which is very similar to CGI Perl scripts. Provides functionality Servlet and JSP are mostly similar, but the implementation in different ways. JSP is usually the majority of HTML code embedded in a small amount of Java code, and all servlets generated by the Java language and HTML.
- XML (Extensible Markup Language): XML is a markup language used to define other languages. It is used in different business processes to share data. The development of XML and Java are independent of each other, but it has the same goal of Java is platform independence. By a combination of Java and XML, you can be a perfect platform independence with a solution.
- JMS (Java Message Service): MS and are used for message-oriented middleware to communicate with each other the Application Programming Interface (API). Supporting both point-to-point domain, there is support for publish / subscribe (publish / subscribe) type of domain, and to provide for the following types of support: Accredited messaging, transactional message delivery, message consistency and durability Supporting subscribers. JMS also provides another way to your application with the old systems Backgrounds.
- JTA (Java Transaction Architecture): JTA defines a standard API, applications can access a variety of matters resulting monitoring.
- JTS (Java Transaction Service): JTS is the CORBA OTS Affairs to monitor the implementation of the basic. JTS transaction manager provides the implementation modalities. The transaction manager are at high-level support for Java Transaction API (JTA) specification, and implementation at the bottom than the OMG OTS specification of Java image. JTS transaction manager for the application server, resource manager, an independent applications, and communications resource manager provides a Transaction Service.
- JavaMail: JavaMail is used to access the mail server API, which provides a set of abstract class mail server. Not only support the SMTP server also supports the IMAP server.
- JTA (JavaBeans Activation Framework): JavaMail use JAF to handle MIME encoded e-mail attachment. MIME stream of bytes can be converted into Java objects, or conversion from Java objects. Most applications do not need direct access to all OK JAF.
Reference
- "Develop n-tier application using J2EE" - Steven Gould
- "The Business Benefits of EJB and J2EE Technologies over COM + and Windows DNA"
- "The J2EE Tutorial" chapter overview - Monica Pawlan
- Photos used in this article from "The J2EE Tutorial" in the picture modified from the English.