Shulou(Shulou.com)06/02 Report--

The content of this article mainly revolves around J2EE Weblogic services which are described, the content of the article is clear and easy to understand, organized, very suitable for beginners to learn, worth reading. Interested friends can read along with Xiaobian. I hope everyone gets something out of this article!

J2EE Weblogic Service Usage

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Weblogic Servlet represents logic

Weblogic JavaServer Page (JSP) presentation logic

Weblogic Java Database Connectivity (JDBC) Access to Database Repository

Weblogic Java Transaction API (JTA) Transaction Management

Weblogic Java naming and directory interface central registry of object names

Weblogic Remote Method Invocation (RMI) Distributed Execution of RMI Objects

Weblogic Enterprise JavaBeans (EJB) implement business logic

Weblogic Java Message Service (JMS) coordinates distributed execution

1) logic of expression

Java Servlet, JSP, JavaBean, Tag Library.

1. Java Servlet

Java Servlet is a server-side technology responsible for receiving http requests from web browsers and returning http responses.

It can be multithreaded. Enterprise java standards for developing presentation logic.

Core features of Http Servlet:

（1）HttpServletRequest

（2）HttpSession

（3）HttpServletResponce

2. JSP

JSP technology provides developers with a simple HTML-like page for creating servlets.

JSP can contain Java code, HTML code, and JavaBean module code.

JSP reverses the structure of servlets and centers on tags rather than clumsily embedding HTML tags into Java code.

JSP contains special tags and syntax to contain Java code.

Servlet engine and JSP engine combination, JSP can take advantage of Servlet engine services:

On the *** th request for a JSP page, the application server compiles the page into a Servlet and then executes it for deeper requests.

3. JavaBean

JavaBeans are Java components (classes).

Developers use it in Weblogic Server applications to encapsulate data and rely on databases for display or activity.

JSP pages can contain JavaBeans with special tags and automatically populate them with values,

JSP pages call methods on these JavaBeans to help them create HTML output.

II. Database and transaction support

Database and transaction support is provided by JDBC and JTA. The high-level interfaces used by databases are those provided by EJB.

1. Java Database Connectivity

JDBC is Java's database connectivity standard, and the JDBC specification provides everything you need to connect to a database from the standard Java API set,

Vendors provide JDBC "drivers" that map this standard Java API set to the concrete structure of the underlying database.

From a programming perspective, JDBC is the bridge between Weblogic Server and the database.

2. API support for Java transactions

JTA provides web application developers with access to transactional functionality in the database system or any legacy data store.

Transactions coordinate single and multi-database operations to ensure resource correctness and consistency so that database-dependent operations are repeatable and persistent.

Object Registry and Remote Method Calls

JNDI and RMI

1. Java Naming and Directory Interface

JNDI is Java's standard for a "central registry" of naming and directory services.

JNDI manages references to core components needed to build distributed applications

When a developer creates an application that accesses a remote object, JNDI provides the application in a way that looks up the address of the object.

JNDI usage patterns are simple, application developers do an initial lookup to find the objects they need in their Weblogic Server deployment,

The Weblogic Server service returns everything the application needs to access the object.

2. Remote Method Invocation (RMI)

RMI is a Java standard for Java applications to make method calls on remote Java objects,

RMI enables remote objects to physically appear as if they were located on a local machine.

RMI provides a framework for distributed applications, but it also provides its remote clients for remote methods and services to interact with.

Some methods that allow remote objects to be exported through remote hosts that invoke RMI.

IV. Enterprise JavaBean

EJB is an enterprise Java standard for creating server-side business logic using Java.

Developers can create EJBs that leverage the services provided by the Weblogic Server container.

There are four basic types of EJB:

Entity EJB: Entity bean that encapsulates specific data items in the database;

(2) Message-Driven Bean: message-driven bean, integrating EJB and JMS. Asynchronous processing.

(3) stateful sessions: session beans that capture business rules and methods that persist during a session;

Stateless sessions: Receive requests through RMI, but do not retain any client-related data.

Java Message Service (JMS)

Two examples of messaging using JMS:

Queue model: JMS clients push messages into JMS queues, which are then available to clients

Topic-based publish-subscribe system: Allows publishers to send messages to registered subscribers of JMS topics.

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