The relationship between Java EE specification and SSH three frameworks

Reprinted from: http://blog.csdn.net/bingjing12345/article/details/20641891

Released in 2014

1994-2000 was the era of the great navigation of the Internet.

Note that the following time points are important.

In 1994, Netscape (Netscape) released the Navigator browser version 0.9. This is the first more mature web browser in history, sensation. However, this version of the browser can only be used to browse, do not have the ability to interact with visitors. Netscape is in dire need of a web scripting language that allows browsers to interact with Web pages.

1995 Sun Company renamed the Oak Language Java, officially launched to the market. Sun's hype promises that the language can be "written once, run Everywhere" (write Once, run Anywhere), which seems likely to dominate the future.

1995 May, Netscape made the decision, the future Web scripting language must "look like Java enough", but simpler than Java, so that non-professional web page authors can quickly get started, so JavaScript was born .

1998 When Sun released the JDK1.2 version, it used the new name Java 2 Platform, the "JAVA2 platform", the modified JDK called Java 2 Platform software develping Kit, or J2SDK.

and is divided into Standard Edition (EDITION,J2SE), Enterprise Edition (Enterprises EDITION,J2EE), mini version (MICROEDITION,J2ME). This was the birth of the Java EE .

Sun's design of the Java EE was designed to address the drawbacks of the two-tier model (Client/server).

In traditional mode, the client becomes bloated with too many roles, in which the first deployment is easier, but difficult to upgrade or improve, the extensibility is not ideal, and often based on some proprietary protocol, usually some kind of database protocol. It makes it very difficult to reuse business logic and interface logic.

Java EE divides the development of the website into four layers:

Customer tier components

The Java EE application can be web-based (browser), or it can be based on a traditional approach. The browser side is the main driving html+css+js

Web Tier Components

The Java EE Web Layer component can be a JSP page or a servlets.

Business Layer Components

EJBs do the processing of business logic and database-related operations.

There are three enterprise-class beans: Session beans, Entity beans, and message-driven (Message-driven)

Beans. A session bean represents a temporary interaction with a client program. An entity bean represents a permanent record of a row in a table in a database. When the client program aborts or the server shuts down, there is a potential service to ensure that the entity bean's data is saved. The message-driven bean combines the characteristics of the session bean and the JMS message listener, allowing a business-level component to receive the JMS message asynchronously.

Enterprise Information System Layer

Stores information. Enterprise Information System layer processing enterprise information system software including enterprise infrastructure system such as enterprise resource planning

(ERP), mainframe transaction processing, database systems, and other legacy information systems.

this set of specifications greatly reduces the difficulty of the development of the website, in some ways it is absolutely successful. The development of Web sites is still more difficult . This set of specifications should be set too early, because when the set of norms when the Internet is developing rapidly, can be described with rapid.

Sun's company was down in 2000 when the Internet bubble took place. At the same time, there are a bunch of unknown small internet companies. Maybe it was a bunch of people who did the site at that time, after all, a lot of companies were shut down. Some people find thattheJava EE specification is bloated, inefficient, difficult to use and out of the reality. So they made up their minds and reformed them.

2000-2001 years Craig felt that the Web layer could use the MVC framework to make the layer easier to develop, so there was struts, which was a good implementation of the original specification and did not produce a qualitative breakthrough.

2001-2003 years Gavin feel that the EJB connection data parts need to be improved, so there is a hibernate,hibernate and not be regulated, but how to change how to change.

2002 years or so, Html+css+js began to separate.

2002-2004 years Rod felt that the dependency between classes and classes should be improved, so the spring,spring was designed to make Java EE specifications easier to use, so it was radically modified. At that time to see absolutely is to take its essence, to its dross.

So does Spring replace the EJB?

From 1998 to 2004, Sun could not have found the problem of the existence of the Java EE, but since 2000 sun will be powerless, because its stock plummeted, the fall of the remaining fraction. This is the time and space in which SSH frames are born.

It seems that the crisis is precisely our turnaround, in the dark to see the hope that our achievements can exceed our imagination.

Summarize:

Does it mean that we don't have to learn the Java EE specification now? But to learn Spring.

Spring is based on the Java EE but does not fully follow the Java EE.

Spring is what you use to configure what, lightweight. Yes, over.

The relationship between Java EE specification and SSH three frameworks