Basic question abt servlet engines

[Navodit]

I have a very elementary question abt the concept of using servlet engines
(like Jrun) or application servers for running java servlets on a
webserver(like IIS). What I understand is as follows:
When the webserver receives a request it directs this to the application
server which in turn processes the servlet and sends the response to the
webserver from where it is sent to the client. I am not fully clear as to
why we need a servlet engine/application server at all ? For example when we
are running applets on the webserver we donot need an application server. So
why do we need it for servlets ? If someone can shed light on the basic
concept here it would be great ! Thanks,

 

[Matt Humphrey]

I have a very elementary question abt the concept of using servlet engines
(like Jrun) or application servers for running java servlets on a
webserver(like IIS). What I understand is as follows:
When the webserver receives a request it directs this to the application
server which in turn processes the servlet and sends the response to the
webserver from where it is sent to the client. I am not fully clear as to
why we need a servlet engine/application server at all ? For example when
we are running applets on the webserver we donot need an application
server. So why do we need it for servlets ? If someone can shed light on
the basic concept here it would be great ! Thanks,

First off, applets do not run on the webserver--they run in the client's
browser and really don't enter into the picture of web vs. app servers. So
setting that aside, large, scalable systems use a webserver with an
application server because a good deal of content (images, documents, lead
pages, applets, flash media) is static and is more efficiently served (and
cached, shared, distributed as appropriate) simply by a webserver. Servlets
(and JSP, etc) and other functional content requires some computational
resources for each request and so must be handled by some kind of engine.
Servlets share a JVM which reduces startup costs and allows better long-term
performance through resource pooling and even helps with deployment by
allowing dynamic code replacement (via classloaders, etc)

Matt Humphrey (e-mail address removed) http://www.iviz.com/

 

[Navodit]

First off, applets do not run on the webserver--they run in the client's
browser and really don't enter into the picture of web vs. app servers.
So setting that aside, large, scalable systems use a webserver with an
application server because a good deal of content (images, documents, lead
pages, applets, flash media) is static and is more efficiently served (and
cached, shared, distributed as appropriate) simply by a webserver.
Servlets (and JSP, etc) and other functional content requires some
computational resources for each request and so must be handled by some
kind of engine. Servlets share a JVM which reduces startup costs and
allows better long-term performance through resource pooling and even
helps with deployment by allowing dynamic code replacement (via
classloaders, etc)

Matt Humphrey (e-mail address removed) http://www.iviz.com/

Thanks ! I think I get the picture now ...