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Re: Need to learn J2EE and friends

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nroberts wrote:
> I've recently been assigned as engineer to adopt a product written in
> Java that uses J2EE, EJB, and Struts.  After the upcoming maintenance
> release a decision to re-engineer the product has already been made.
> 
> I have tons of experience in C++ and in object oriented programming,
> and in that regard Java is no challenge to me...only a slightly
> different syntax and a different API.  The architecture of
> "enterprise" applications though is entirely new and as I get into
> it...quite a bit foreign.  There seems to be a rigor and logic to the
> Java way that I need to learn.  I did a modicum of work on dynamic web
> programming with PHP way back in the day but even that appears quite
> different from what I'm tasked to work on now.  My primary experience
> is in desktop application programming.
> 
> I went to the local instance of Barnse and Noble to find something to
> help but found little of value.  The most tempting offering was a
> generic book on SOA but I was not sure how much help it would be and
> it was rather expensive.  I'm not even sure SOA would be topical since
> we're not developing a "service" at all.  I'm working through a
> tutorial on using Eclipse with glassfish but at some point I need to
> break out of the IDE and understand the generic project structure.  We
> appear to be using Ant for the build process...  Frankly, I wasn't
> sure would help me as I looked at the bookshelf.  Most books just
> seemed to be thick for the sake of being thick, going over things like
> XML syntax basics, while I need concise, upper level treatment and
> overview.
> 
> I need to get up to speed on the concepts regarding these multi-tier
> web programs and how they fit in with Beans and Struts...perhaps new
> technologies that would be of help as well.  I need to learn the
> differences between application programming and "enterprise"
> programming and I also need to learn what I need to learn...because I
> don't even seem to really know that either.
> 
> Where would be a good place to start?

When you say "J2EE" and "EJB", do you have any information on what versions of those you're working with?  Also, what specific implementation are you using (WebLogic, JBoss, Glassfish, ...)?  Or are you tasked with picking an implementation?

It makes a difference what version you're using.  The abbreviation "J2EE" is somewhat out of date, referring to an older version of the spec that is harder to work with than the current version, "Java EE" (Java Enterprise Edition).

http://java.sun.com/javaee/6/docs/tutorial/doc/
(Java EE 5 is the older version.  "J2EE" refers to still older versions.)

"EJB", or "Enterprise Java Beans", has changed a lot with the spec upgrade.  There used to be two kinds, "session beans" and "entity beans".  Entity beans have fallen into disfavor, being replaced by the Java Persistence API (JPA).  Entity beans were never easy to work with, but JPA is a joy.  (Use EclipseLink or OpenJPA rather than Hibernate if you can help it.  If you must use Hibernate, use it as a JPA library, not in its native mode.)

Nowadays you have session beans - stateful and stateless - and management beans.  They are much easier to use in Java EE than they were in J2EE.  The old way involved a lot of fooferol around "home interface" and "remote interface" that were hard to use.  Nowadays we use annotations (syntactic elements identified by a leading "@" character such as "@Session") and things just sort of automagically happen in the application server.  

The application server is the Java EE engine, such as the aforementioned WebLogic, JBoss or Glassfish; also Geronimo, WebSphere, what-have-you.

You really, really want to avoid the J2EE way of doing things and stick with Java EE.  Any application server that doesn't support at least Java EE 5 is going to be hard to work with and likely no longer supported (except maybe at significant expense) by the vendor.  The development and maintenance costs of these older versions will outweigh conversion costs to a newer platform. 

Download and install Glassfish - it's lightweight enough to run on any decent developer workstation (dual-core or better, 2 GB RAM or better, couple of hundred megs of disk or better).
http://glassfish.java.net/

Use it to work through at least some of the aforementioned tutorial.
http://java.sun.com/javaee/6/docs/tutorial/doc/

-- 
Lew

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Thread

Need to learn J2EE and friends nroberts <roberts.noah@gmail.com> - 2011-09-05 18:23 -0700
  Re: Need to learn J2EE and friends Lew <lewbloch@gmail.com> - 2011-09-05 18:48 -0700
    Re: Need to learn J2EE and friends nroberts <roberts.noah@gmail.com> - 2011-09-06 09:05 -0700
      Re: Need to learn J2EE and friends Lew <lewbloch@gmail.com> - 2011-09-06 15:03 -0700
      Re: Need to learn J2EE and friends Arne Vajhøj <arne@vajhoej.dk> - 2011-09-06 19:09 -0400
  Re: Need to learn J2EE and friends Arne Vajhøj <arne@vajhoej.dk> - 2011-09-05 21:49 -0400
  Re: Need to learn J2EE and friends markspace <-@.> - 2011-09-05 18:58 -0700
  Re: Need to learn J2EE and friends Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-09-06 06:20 -0300
    Re: Need to learn J2EE and friends nroberts <roberts.noah@gmail.com> - 2011-09-06 08:06 -0700
      Re: Need to learn J2EE and friends Arne Vajhøj <arne@vajhoej.dk> - 2011-09-06 19:06 -0400
        Re: Need to learn J2EE and friends markspace <-@.> - 2011-09-06 17:30 -0700
          Re: Need to learn J2EE and friends Arne Vajhøj <arne@vajhoej.dk> - 2011-09-06 20:42 -0400
    Re: Need to learn J2EE and friends Arne Vajhøj <arne@vajhoej.dk> - 2011-09-06 19:01 -0400
      Re: Need to learn J2EE and friends Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-09-06 21:09 -0300

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