what is application server? What are Rich Internet Applications?

Question

I'm from a PHP background. All I know is that

1. web server handles the http request
2. PHP interpreter that is embedded into web server compiles the PHP script
3. The result of above will be HTML, which is returned to client again by the webserver.

Now, I don't understand one thing. what is application server? What is the difference between webserver & application server. Any popular example of its role?

and what are What are Rich Internet Applications? From my understanding its just a fancy name for web applications like google docs. Am I right?

Some one please explain with examples.

Answer 1

The line between web servers and application servers is blurred. One common definition is that web servers can be contacted through HTTP and HTTPS only, but application servers can be contacted through other means (messaging services, remote method invocation, etc) in addition to web protocols. Application servers also provide a container that takes care of certain software requirements (such as transactions and resource management) for you automatically.

And rich internet application are web apps that act like desktop apps. They don't have to reload the page every time you perform an action, and they have a wider variety of input methods. This can be done in a variety of ways, including Flash, Silverlight, Java, or regular HTML with Ajax Javascript.