J2EE13 a specification-"Java EE"

2. JDBC (Java Database Connectivity): The JDBC API provides a unified way to access different databases, like ODBC, where JDBC shields developers of details, and JDCB access to the database is platform agnostic. JDBC is similar to ODBC code, and is a function of database linking.
4. Jndi (Java name and directory Interface): The Jndi API is used to perform name and directory services. It provides a consistent model for accessing and manipulating enterprise-class resources such as DNS and LDAP, local file systems, or application server objects. Jndi avoids the tight coupling between the program and the database, making the application easier to configure and easy to deploy. (http://blog.csdn.net/zhaosg198312/article/details/3979435)

   Jndi is a lookup service: primarily used for lookups, Web application environment variables, EJBS and their environment variables, through Datasouces database connection pools, JMS targets, and connection factories.

6. EJB (Enterprise JavaBean): One of the reasons why the EE technology has won a body's attention is EJB. They provide a framework for developing and implementing distributed business logic, which significantly simplifies the development of scalable and highly complex enterprise-class applications. The EJB specification defines when EJB components interact with their containers. Containers are responsible for providing common services, such as directory services, transaction management, security, resource pooling, and fault tolerance. But it's worth noting that EJB is not the only way to implement Java EE. It is because of the openness of the Java EE that some vendors can achieve the same goal in a parallel way with EJBS.
   Contains four types of objects: Stateless session bean, stateful session bean, entity bean, message-driven bean (consumer of JMS)
8. RMI (Remote method Invoke): The RMI protocol invokes a method on a remote object, as its name indicates. It uses serialization to pass data on the client and server side. RMI is a lower-level protocol that is used by EJBS.
10. Java Idl/corba: With the support of Java IDL, developers can integrate Java with CORBA. They can create Java objects and make them expandable in the CORBA orb, or they can create Java classes and serve as clients for CORBA objects that are expanded with other orbs. The latter approach provides another way through which Java can be used to integrate your new application with the old system.
12. JSP (Java Server pages): JSP pages consist of HTML code and embedded Java code. The server processes the Java code after the page is requested by the client, and then returns the resulting HTML page to the client's browser. Similar to ASP code, only the details are different <%%> the code inside is Java code, not JS code. JSP file-(conversion)--. Java file servlet code-(compile)--. class file Servlet code
    
    
14. Java Servlet:servlet is a small Java program that extends the functionality of the Web server. As a server-side application, it starts executing when requested, and is similar to CGI perl scripts. Servlets provide much more functionality than JSPs, but they are implemented in different ways. JSPs are usually embedded in a small amount of Java code in most HTML code, and Servlets are all written in Java and generate HTML. the generic servlet acts as the controller's role and belongs to the Web container. A servlet is a Java class that provides protocol-based request/response services.
    

16. 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 it and Java have the same goal is platform independence. By combining Java and XML, you can get a perfect platform-independent solution.
18. JMS (Java Message Service): MS is an application interface (API) for communicating with each other for message-oriented middleware. It supports both point-to-point domains, domains that support publish/subscribe (Publish/subscribe) types, and provides support for the following types of messages: Approved messaging, transactional message delivery, consistent messaging, and persistent subscriber support. JMS also provides another way to integrate your application with the old backend system.
20. JTA (Java Transaction Architecture): JTA defines a standard API that enables the application system to access various transaction monitoring.
22. JTS (Java Transaction Service): JTS is the basic implementation of CORBA OTS transaction monitoring. The JTS specifies how the transaction manager is implemented. The transaction manager is a Java image that supports the Java Transaction API (JTA) specification at the top level and implements the OMG OTS specification in the lower layer. The JTS transaction Manager provides transactional services for application servers, resource managers, stand-alone applications, and communication Explorer. a transaction is either done or not done. Has four properties acid,atomic atomicity: The transaction is indivisible, either executed or not executed. Consistent consistency: If an exception occurs halfway through, the transaction reverts to its original state. Isolated, Independence: Lock, operation, other transactions can not interfere. Durable persistence: After successful operation, data persistence is maintained. Transactions span EJB Access, JDBC Access, JMS connections.
    
24. Javamail:javamail is an API for accessing mail servers, which provides an abstract class of mail servers. Supports not only SMTP servers, but also IMAP servers.
26. JTA (JavaBeans Activation Framework): JavaMail uses JAF to process MIME-encoded message attachments. The MIME byte stream can be converted to a Java object or converted from a Java object. Most applications do not need to use JAF directly.

J2EE13 a specification-"Java EE"