(transfer) 13 core technologies of J2EE

1、 JDBC (Java database connectivity)

JDBC API provides a unified way to access different databases. Like ODBC, JDBC shields developers from some details. In addition, JDBC's access to databases is platform independent.

2、 JNDI (Java name and Directory Interface)

The JNDI API is used to execute name and directory services. It provides a consistent model to access and manipulate enterprise resources such as DNS and LDAP, local file systems, or objects in application servers.

3、 EJB (enterprise JavaBean)

One of the reasons why J2EE technology has won extensive attention from the media is EJB. They provide a framework to develop and implement distributed business logic, which significantly simplifies the development of scalable and highly complex enterprise applications. The EJB specification defines when and how EJB components interact with their containers. Containers are responsible for providing common services, such as directory services, transaction management, security, resource buffer pools, and fault tolerance. But it is worth noting that EJB is not the only way to implement J2EE. Because of the openness of J2EE, some manufacturers can achieve the same goal in a parallel way with EJB.

4、 RMI (remote method invoke)

Call a method on a remote object. It uses serialization to pass data between the client and server. RMI is a lower level protocol used by EJBs.

5、 Java IDL / CORBA

With the support of Java IDL, developers can integrate Java and CORBA. They can create Java objects and make them deployable in CORBA orbs, or they can also create Java classes and act as clients of CORBA objects deployed with other orbs. The latter method provides another way through which Java can be used to integrate your new application with your old system.

6、 JSP (Java Server Pages)

A JSP page consists of HTML code and Java code embedded in it. After the page is requested by the client, the server processes these Java codes, and then returns the generated HTML page to the client's browser.

7、 Java servlet

Servlet is a small java program that extends the functions of web server. As a server-side application, it starts executing when requested, which is very similar to CGI Perl script. Most of the functions provided by servlets are similar to JSP, but they are implemented in different ways. JSP is usually a small amount of Java code embedded in most HTML code, and servlets are all written in Java and generate HTML.

8、 XML (Extensible Markup Language)

XML is a language that can be used to define other markup languages. It is used to share data in different business processes.

The development of XML and Java are independent of each other, but the same goal as Java is platform independence. By combining Java and XML, you can get a perfect platform independent solution.

9、 JMS (Java Message Service)

JMS is an application program interface (API) used to communicate with message oriented middleware. It supports both point-to-point domain and publish / subscribe (publish / subscribe) domain, and provides support for the following types: approved messaging, transactional messaging, consistent messaging and persistent subscriber support. JMS also provides another way to integrate your application with the old background system.

10、 JTA (Java transaction Architecture)

JTA defines a standard API so that application systems can access various transaction monitoring.

11、 JTS (Java transaction service)

JTS is the basic implementation of CORBA OTS transaction monitoring. JTS specifies the implementation of the transaction manager. The transaction manager supports the Java transaction API (JTA) specification at the high level and implements the java image of OMG OTS specification at the lower level. The JTS transaction manager provides transaction services for application servers, resource managers, independent applications and communication resource managers.

12、 JavaMail

JavaMail is an API for accessing mail server. It provides a set of abstract classes of mail server. It supports not only SMTP server but also IMAP server.

13、 JAF (JavaBeans activation framework)

JavaMail uses JAF to process mime encoded mail attachments. The byte stream of mime can be converted to or from Java objects. Most applications do not need to use JAF directly.