Difference between Servlets and Java beans
Hi All,
I am very new to Java. I feel very difficult to understand the Java concepts.
especially EJB, java beans, servlets, applets, java script, JSP, model view controller, patterns...etc etc.
Though i read their definitions in books, i am not getting a clear picture as of how these are used in the real time projects.
Now, Let me come to my point,
I know that Servlet is a peice of code that is running on the server. Java beans
is also a Java class that runs on the server.
Could any one of you be kind enough to explain me in basic terms (possibly without using hi-fi jargons), about the difference between a servlet and a Java bean and in what project requirements these are used?
I would 'greatly' appreciate your response.
Thanks in advance,
params
Servlets are java classes designed to serve content from the web, like a web server serves HTML pages. A servlet is used to receive requests, process them, and then return responses to the program that asked for them over a network. In order to function properly, they must be run in the context of a Servlet Container, a special program designed as a middle man between the servlet and the client (program talking to the servlet).
JavaBeans are normal Java Objects that follow some specification restrictions that make them re-useable in many contexts. That means the JavaBean can be run along side of Servlets, or as part of a desktop program, or inside an Applet... The best designed JavaBeans do not know or care about their context, and are thus not limited by them. Do not confuse (however easy it might be) JavaBeans with EJBs, which are rather different.
> Now, Let me come to my point,
> I know that Servlet is a peice of code that is
> running on the server.
No, the more precise way to say it is that a servlet runs inside a servlet/JSP container. The most common kind of servlet, the HttpServlet, is invoked by the servlet/JSP container in response to an HTTP request and generates an HTTP response to send back to the client.
> Java beans is also a Java class that runs on the server.
JavaBeans are software components written in Java that follow the JavaBeans specification. They don't require a container to run, just a JDK/JRE.
You might be thinking of Enterprise Java Beans, which are very different from mere JavaBeans. EJBs, like servlets, require a container in which to run (an EJB container, as you might guess). EJBs are software components designed for use in distributed, transactional, persistent, scalable enterprise apps. (Look up each one of those terms if you don't know what they mean.) They use the Java RMI-IIOP protocol to communicate.
EJBs are part of the larger J2EE spec, which includes JavaBeans, servlets, JSPs, EJBs, and lots of other stuff like message queues, transactions, relational databases, etc.
Better?
%
