13 J2EE specifications

The J2EE platform consists of a complete set of services, application interfaces (APIS), and Protocols. It provides Function Support for developing web-based multi-layer applications, the following is a brief description of the 13 technical specifications in J2EE (limited by space ):

 

1. JDBC(Java database connectivity ):

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

 

2. JNDI(Java name and Directory Interface ):

Jndiapi is used to run the name and directory services. It provides a consistent model to access and operate enterprise-level resources such as DNS and LDAP, local file systems, or objects on application servers.

 

3. EJB(Enterprise JavaBean ):

One of the reasons why J2EE technology has won wide attention is EJB. They provide a framework for developing and implementing distributed business logic, significantly simplifying the development of scalable and highly complex enterprise-level applications. The EJB specification defines when and how the EJB component interacts with their containers. Containers are responsible for providing public services, such as directory services, transaction management, security, resource buffer pools, and fault tolerance. However, it is worth noting that EJB is not the only way to implement J2EE. Due to the openness of J2EE, some vendors can achieve the same purpose in parallel with EJB.

 

4. RMI(Remote Method invoke ):

As its name indicates, the RMI protocol calls methods on remote objects. It uses serialization to transmit data on the client and server. RMI is a more underlying protocol used by EJB.

 

5. Java IDL/CORBA:

With the support of javaidl, developers can integrate Java and CORBA. They can create Java objects and expand them in corba orb, or they can also create Java classes and serve as the customers of the CORBA objects expanded with other orb. The latter method provides another way through which Java can be used to integrate your new applications with old systems.

 

6. jsp(Java Server Pages ):

A JSP page consists of HTML code and Java code embedded in it. The server processes the Java code after the page is requested by the client, and then returns the generated HTML page to the browser of the client.

 

7. Java Servlet:

Servlet is a small Java program that extends the functions of web servers. As a server-side application, it is executed when requested, which is similar to the cgiperl script. Most of the functions provided by Servlet are similar to those provided by JSP, but the implementation methods are different. JSP usually embeds a small amount of Java code in most HTML code, while servlets is all written in Java and generates 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 mutually independent. However, the same objective of XML and 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 interface (API) used to communicate with message-oriented middleware ). It supports both point-to-point domains and publish/subscribe domains, and supports the following types: Approved message transmission and transactional message transmission, supports consistent messages and persistent subscribers. JMS also provides another way to integrate your application with the old background system.

 

10. JTA(Java transactionapi ):

JTA defines a standard API, which allows the application system to access various transaction monitoring data.

 

11. JTs(Java Transaction Service ):

JTs is the basic implementation of corbaots transaction monitoring. JTs specifies the implementation method of the Transaction Manager. The transaction manager is a Java image that supports the Java transaction API (JTA) specification at the high-level level and implements OMG otsspecification at a lower level. JTs Transaction Manager provides transaction services for application servers, resource managers, independent applications, and communication resource managers.

 

12. javamail:

Javamail is an API used to access the mail server. It provides a set of abstract classes for the mail server. Not only supports SMTP servers, but also supports IMAP servers.

 

13. JAF(JavaBeans activation framework ):

Javamail uses JAF to process MIME-encoded email attachments. Mime byte streams can be converted to Java objects or to Java objects. Most applications do not need to use JAF directly.