Question

I am a little confused about the roles of a java application server and its differences from a web server.
I found many sites explaining the same difference between the two but not to my satisfaction.
So please explain me about the two following cases:-

1)App. Server and its difference with web server:

From these two links:
Difference between an application server and a servlet container?
What is the difference between application server and web server?

web server: It handles everything through http protocol by accepting requests from clients and sending
responses to them with the help of its servlet container(e.g Apache Tomcat)
App. Server: An application server supports the whole of JavaEE like JMS,JPA,RPC etc.

Now what I am confused with is that how can I use a lot of JavaEE APIs like JMS,JPA etc. with my Tomcat
by adding their jar files in my web application ?
Does that mean that if I use an appliation server I don’t have to add those jar files?(I don’t think so)

2)The roles of an appl. server (This is very important to me)

From Wikipedia
http://en.wikipedia.org/wiki/Application_Server

An application server provides services such as security,transaction support etc.
“The term is often used for web servers which support the JavaEE” — It sounds like if we add the required jar files of JavaEE APIs a web server becomes an appl. server.What about it.

Now my question is how an application server performs the tasks of security control or transaction management by itself ?
E.g. in my web application using Spring framework I am providing security by using spring-security and transaction management by using @Transactional annotation and all those things you know.
So does the appl. server have anything to do with my security or transaction management or it has its own ways ?

Forgive my ignorance.

Answer 1

Using Spring, you’re in fact embedding some kind of Java EE container inside your application. But even when using Spring, if you need JTA support (because you need distributed XA transactions), you’ll need to use an additional transaction manager. If you need JMS, you’ll need to install an additional JMS broker. If you need connection pooling, you’ll need to use an additional connection pool. Sometimes it’s as simple as adding additional jars to the classpath and properties or XML files. Sometimes it’s harder.

A Java EE app server comes with everything bundled. You have less flexibility, but you don’t need to install, configure and make everything work by yourself.