Re: from j2sdk to j2ee ?

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Date: Sun, 20 Mar 2005 13:49:21 GMT

On Sat, 19 Mar 2005 22:58:31 +0100, Dado wrote:

>
> Until today I developed, small but usefull, desktop applications, using
> j2sdk. Now, I'm thinking about developing a web appllication.
> When I started learning java, I was thinking that the natural progress is
> from j2sdk to j2ee, but somewhere I red that it isn't so simple.
> 1.
> Is it really so big step ?
> I must admit that in this moment I'm a little confuse with all this
> tehnologies: JSP, Servlet.. .what to choose for my first web application.

Big? Possibly. Significant? Absolutely, as you will be extending past
pure Java and need to be aware of other environments while developing.
Scary big? No.

J2EE operates inside a J2EE container, which is a JVM with the required
J2EE libraries that runs 24x7. The container is made aware of your app by
placing the app components into a structured directory tree, by updating
the container's XML-based configuration, and (if necessary) by restarting
(virtual reboot) of the container. Several apps could run in one
container, and an app can be spread across several containers. SO you
will need to learn a new set of libraries. Pick a container, such as
TomCat, to get started.

J2EE can be considered a superset of Java. You need to make sure your Java
is really solid, as you will be stepping into a world that references Java
through shortcuts and non-Java mechanisms such as tags. You will be
looking up things from external information sources and using the results
to affect code. Proficiency in XML as well as knowledge and understanding
of directory principals are an asset.

J2EE has 2 distinct sides - the Web side and the Business side. Perhaps a
contraversial statement, but I believe these take to distinct skill sets.
I point to the separate & independent certifications by Sun to support
this assertion. And I think it is rare to find excellence in both within
one person.

The Web side is largely represented by the JSP/Servlet world. IMO, this
side shows the power of J2EE. Reasonably easy to learn and very useful.
Points to a person with strong graphical serse as well as a strong Java
sense. Especially when extending the JSP tag libraries, this requires a
good handle on how and when to split routines and expose functionality
segments. Quite interesting and potentially very challenging.

The Business logic side can truly be a mind-twister at first. It comes
from a distributed object mind-set and requires a developer to think
concurrently in terms of local and remote controllers and local and remote
implementors. I'd encourage waiting for this, or even looking for
alternatives to this side as I happen to agree with the authors of
"Better, Faster, Lighter Java".

I refer you to the excellent http://www.theserverside.com site for
information and especially to the free downloadable reference books under
the articles section.

Also there is a misguided belief that one can write universally performant
database independent applications using J2EE. It is true that J2EE does
support database independence, but it does not (IMO, as yet 'can not')
take into account internal mechanisms such as locking, which can
dramatically affect programming methods. As a result I've found, except
for the most basic, even simplistic, applications, simply switching data
sources can give startling differences in performance.

/Hans

The above is my opinion based on my experience. I expect many challenges,
especially by people who have misread what I wrote. Although I intend to
read responses, I will probably not respond to challenges. So let the
flames begin <g>!!

• Previous message: Kris M: "Re: Coppied from alt.comp.lang.java"
• In reply to: Dado: "from j2sdk to j2ee ?"
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