Questions re. J2EE and Tomcat interactions/relations

[mot12345]

I have been using j2sdk1.4.1_01 and jakarta-tomcat-5.0.16 on Windows
XP/SP1 systems for servlet and JSP development for quite some time.
I'm very familiar with both Tomcat and Java. Now I want to go to
J2EE. I've looked closely at http://java.sun.com/j2ee/, but I'm
confused about the alphabet soup there (such as "Sun Java System
Application Server Platform Edition 8.1 2005Q2 UR2")

Questions:
1) How does J2SE (such as J2SE 5.0) relate to the good old J2SDK (such
as j2sdk1.4.1)?

2) Will installation of "J2EE 1.4 SDK", with its bundled J2SE 5.0,
override my existing j2sdk1.4.1?

3) Will installation of the "Sun Java System Application Server
Platform" interfere with my existing Tomcat installation

4)Can the "Sun Java System Application Server" run servlets and JSPs on
it's own or does it need a container/web server like Tomcat for that?

5) Can the "Sun Java System Application Server" replace Tomcat (perform
the functions Tomcat does)?

Thanks for providing any insights.

Wolfgang,
Santa Barbara, CA

P.S.:
My questions are motivated by my desire to expand my capabilities by
going from Tomcat to J2EE. It seemed the best way to go about this is
to just download and install the latest J2EE 1.4 SDK from
http://java.sun.com/j2ee/1.4/download.html#sdk
There, I find that I can get the separate components
" Sun Java System Application Server Platform Edition 8.1 2005Q2 UR2
" J2SE 5.0

I've tried my best to read through the confusion and obfuscation of
terms at
http://java.sun.com/j2ee/ (including the J2EE FAQ at
http://java.sun.com/j2ee/faq.html) but I fail to understand what the
"System Application Server" really is, and how all this interacts with
Tomcat and previous versions of JDK.

 

[.]

I have been using j2sdk1.4.1_01 and jakarta-tomcat-5.0.16 on Windows
XP/SP1 systems for servlet and JSP development for quite some time.
I'm very familiar with both Tomcat and Java. Now I want to go to
J2EE. I've looked closely at http://java.sun.com/j2ee/, but I'm
confused about the alphabet soup there (such as "Sun Java System
Application Server Platform Edition 8.1 2005Q2 UR2")

Questions:
1) How does J2SE (such as J2SE 5.0) relate to the good old J2SDK (such
as j2sdk1.4.1)?

J2SE = Java 2, Standard Edition. The J2SE SDK is the J2SE Software
Development Kit. That is, the code you need to develop J2SE applications.

2) Will installation of "J2EE 1.4 SDK", with its bundled J2SE 5.0,
override my existing j2sdk1.4.1?

Sort of. If you have things that depend on JAVA_HOME or CLASSPATH the J2EE
1.4 SDK might change these. You need to understand how CLASSPATH and other
environment variables work. Some integrated development environments
(IDEs; e.g. NetBeans or IDEA) will ignore the environment variables and
let you specific SDK (also called JDK) information inside the IDE.

3) Will installation of the "Sun Java System Application Server
Platform" interfere with my existing Tomcat installation

No. If you run it and Tomcat at the same time, maybe. Just installing it
will not affect the Tomcat (I have tomcat, weblogic, sun java sas and a
few others installed without problems).

4)Can the "Sun Java System Application Server" run servlets and JSPs on
it's own or does it need a container/web server like Tomcat for that?

SJSAS can run servlets and JSPs on its own.

5) Can the "Sun Java System Application Server" replace Tomcat (perform
the functions Tomcat does)?

I believe anything you can do with tomcat you can do with SJSAS but I'm
not sure if it has the same performance characteristics as tomcat. If
tomcat is all you need then I'd suggest you stick with tomcat.

Thanks for providing any insights.

Wolfgang,
Santa Barbara, CA

P.S.:
My questions are motivated by my desire to expand my capabilities by
going from Tomcat to J2EE. It seemed the best way to go about this is
to just download and install the latest J2EE 1.4 SDK from
http://java.sun.com/j2ee/1.4/download.html#sdk
There, I find that I can get the separate components
" Sun Java System Application Server Platform Edition 8.1 2005Q2 UR2
" J2SE 5.0

I've tried my best to read through the confusion and obfuscation of
terms at
http://java.sun.com/j2ee/ (including the J2EE FAQ at
http://java.sun.com/j2ee/faq.html) but I fail to understand what the
"System Application Server" really is, and how all this interacts with
Tomcat and previous versions of JDK.

Think of the sun java system application server as a replacement for
tomcat.

NOTE: if you know JSP and servlets then you know a little J2EE. J2EE is
just J2SE with certain framework support. Namely: JSP, Servlet, EJB, JMS,
JNDI, etc. How you write JSPs and Servlets will be the same. How you
deploy them is the big difference between application servers. Tomcat is
much easier. You just drop the files in the appropriate diretory and you
are good to go. Other app servers require you to use the admin console to
deploy the files (it uploads them to some location and updates XML config
files as needed).

All the information you need is on the Sun web site. It just takes a bit
of time to get through all the acronymns. Question everything. Don't
assume you understand the meaning of some words.