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Java Coffee Break Newsletter Volume 3 Issue 10
Java Coffee Break Newsletter Volume 3, Issue 10
http://www.javacoffeebreak.com/
ISSN 1442-3790
=================================================================
In this issue
* Featured Java Websites
* Book Review - Web Development with JavaServer Pages
* Book Review - Java in a Nutshell, 3rd Edition
* Interview with Duane K. Fields, and Mark A. Kolb, on JSP
* Interview with Ed Roman, on Enterprise JavaBeans
* Q&A : What does a void return value mean? Which class is
being returned?
=================================================================
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Featured Java Websites
Each month, we feature a selection of premium websites devoted
to the Java programming language, and software development in
general. Here are a selection of websites that may be of interest
to readers.
A simple introduction to CORBA
Trying to get your head around distributed objects and
CORBA? It can be a tricky topic, but don't worry; this
simple tutorial takes you through the steps involved in
writing CORBA clients and servers, using VisiBroker and
Java. The well-organized and explanatory approach
facilitates digestibility and therefore speeds your
progress. While there is certainly more to know beyond
this source, it is a good place to start by learning
about the theory involved with CORBA, along with some
practical code.
http://www.javacommerce.com/CorbaNotes/index.htm
Painting on a Java canvas
No, I'm not talking about the artistic applications of
coffee (though as a stimulant, I'm sure it's had an effect
on the art world at one time or another). I'm talking about
the Java canvas, or more specifically, the AWT Canvas class.
A mysterious component indeed, as it forms that basis for
just about every component in Java you can think of from
buttons to lists and text fields. Learn more about it in
this fascinating article.
http://www.easynet.it/~jhl/test/TestCanvas.html
Intelligent agents, spiders and bots
Botspot.com has a comprehensive section on bots that is
billed as "The Spot for All Bots on the Net." If you're
interested in writing intelligent agents that whiz across
the Internet, smart software robots that gather information,
or bargaining with merchants for the best deals, you'll
find what you need here. A huge collection of Internet
bots, agent research, and bot news awaits!
http://www.botspot.com/
/* ....adv
* Have you ever considered writing technical articles? Be the
* envy of your peers, and give back to the Java community.
* We're looking for technical articles of interest to Java
* programmers.
* If you have an article you think is suitable, drop us a note
* at --> articles@javacoffeebreak.com
*/
=================================================================
Book Review - Web Development with JavaServer Pages
Author : Duane K. Fields, Mark A. Kolb
Publisher : Manning
ISBN : 1-8847779-96
Experience: Intermediate - Expert
Web Development with JavaServer Pages teaches the reader to
construct rich interactive websites using JavaServer Pages
technology. You may be wondering why JavaServer Pages is so
useful, and how it can competes with other technologies like
ActiveServerPages or CGI script. JavaServer pages allows you
to abstract the web design aspect done by web designers from
the programming down by programmers. This means that web
developers can concentrate on beautiful pages, and developers
can concentrate on cutting good code. This makes it an
important component of web development, and a cornerstone
of Java 2 Enterprise Edition (J2EE) Platform.
This book offers a very comprehensive guide to the world of
JavaServer programming, covering both theory and practical
JavaServer programming in great detail. While the book is
filled with many small practical examples, it also has a
larger project which shows you how to create an FAQ
management system. However, it was slightly disappointing
not to see other large scale projects which would benefit
the reader by seeing JSP in action.
Web Development with JavaServer Pages covers all the
fundamentals of JSP programming while providing easy to
understand and concise examples. While the lack of many
large-scale projects may detract from the usefulness of the
book for some developers, it is nonetheless a fine guide to
JSP that competes well with other similarly titled books
-- Michael Reilly
For more information about this title, or to order it, visit
http://www.davidreilly.com/goto.cgi?isbn=0782121713
=================================================================
Book Review - Java in a Nutshell
Author : David Flanagan
Publisher : O'Reilly
ISBN : 1565924878
Experience: Intermediate - Expert
You can read an extract from Java in a Nutshell by visiting
http://www.javacoffeebreak.com/books/extracts/javanutshell
Java in a Nutshell, 3rd Edition, is the sequel to the highly
successful series of books by author David Flanagan. His books
have been both a handy reference when programming, and a
quick-start guide to learning the Java language. Unlike
other authors, when David releases a new edition, it is very
much a complete rewrite, rather than just adding a chapter
here and there.
This is, however, a double-edged sword. It means that you can
pick up the latest edition, and still find it useful if you've
read previous ones. However, to conserve space, the book
becomes more and more compact, so some of the great
sections like a comparison between C++ and Java from the
first edition is reduced to a two page summary of bullet points.
Java in a Nutshell, 3rd Edition is, nonetheless, the best Java
reference available on the market. It covers all the core Java
technologies, save the Abstract Windowing Toolkit and Swing
graphical libraries, which have been relegated to the new
book "Java Foundation Classes in a Nutshell". This will be a
disappointment to some, but if you're looking for a language
reference, and not a guide to GUI programming, this title is
an excellent buy. Particularly if you're new to the Nutshell
series, David Flanagan's fast paced guide to Java is a perfect
desktop reference -- David Reilly
For more information about this title, or to order it, visit
http://www.davidreilly.com/goto.cgi?isbn=1565924878
=================================================================
Interview with Duane K. Fields, and Mark A. Kolb,
on JavaServer Pages
Duane Fields is a web applications developer and
recognized Java expert, while Mark Kolb has been
programming in Java since 1996, and in
object-oriented languages since 1984. Together, they
co-authored "Web Development with JavaServer Pages".
Q: What do you believe has been the biggest change affecting the
Java community in the last year?
A: Duane and Mark - The biggest changes we've seen in the past
year is the rapid acceptance of J2EE and the emergence of no or
low cost application servers. A year ago support for servlets,
JSP, was a bolt-on to other servers, and a free (at least for
development) EJB server was nowhere to be found. Today servers
like Orion and JRun are available for aspiring server side Java
developers to sink their teeth into. I think the availability
of such servers is allowing companies to investigate J2EE as
well, without having to outlay a large sum of cash up front.
Q: How do you find Java stacks up to other programming languages,
such as C++ or VBScript for ASP?
A: Duane - In terms of rich, object oriented design Java is the
only game in town, in my opinion. ASP is by definition locked
into Microsoft's platform, and doesn't offer the clean,
modular abstraction one can obtain with Java.
Q: How does Java Server Pages stack up to competing technologies
like Microsoft's Active Server Pages (ASP)? Can JSP match the
performance and scalability of ASP, or should developers be
evaluating other issues such as portability and ease-of-use?
A: Mark - If just addressing performance issues, NT solutions
like ASP are throttled by the fact that they only run on NT.
In my experience a similarly equipped Unix machine will beat
the NT box in terms of scalability, concurrent connections,
and performance. The performance of JSPs are a function of
the performance of the VM, the application server, and the
hardware, so it's hard to make blanket statements.
Duane - All things being equal, in my experience they are
"equally fast". So performance isn't really an issue.
Certainly JSPs are more portable, and in many ways easier
to use. Especially if you stay away from scriptlets
(embedded code) and use the JavaBean related tags. The use
of these tags, and custom ones as well, allows web content
developers without any coding experience to create dynamic
content with JSP.
Q: How do you see JSP in relation to Java servlets? There seems
to be a fair bit of overlap between the two. Are there some
situations where JSP is preferable to servlets, and vice versa?
A: Mark - Well, JSPs ARE servlets really. JSP code gets parsed,
turned into a Java source file, and compiled into a servlet
class on the fly. However, it is useful architecturally to
speak of them as separate beasts. I recommend using servlets
for application control only, deferring all content generation
to the JSPs. For example, to display a record from a database
you should direct the request at a servlet which collects the
data into a bean and forwards the request onto a JSP page for
display. Coders can work on servlets, web developers can work
on the JSPs.
Q: How do you see Java Server Pages fitting into the framework of
the Java 2 Enterprise Edition (J2EE), and Enterprise Java Beans
(EJBs)? Will the average JSP developer need to draw on all the
different technologies in J2EE?
A: Duane - As alluded to in the previous question, JSP is THE
presentation layer for server side applications. JSP allows
you to pull content out of servlets, and I think EJBs are
great for pulling out business logic in to reusable modules.
I think any server side developer working on projects of any
complexity will need to learn EJBs, at least understand how
to access beans written by others.
Q: Since most, if not all, of your readers will be looking to
deploy their JSP applications on the web rather than within
an Intranet environment, what should they look for in a
hosting provider? Are more hosting providers supporting JSP
and servlets, or is it still an ASP lead marketplace?
A: Mark - I don't think they are really competing in that space
so much. I would think most JSP/Servlet developers are not
hosting their pages and applications on ISP machines, but
are rather co-locating their own boxes which they control.
Since until very recently there were no low/no cost J2EE
servers out there, you won't find that many JSP hosting
services.
Q: While there are plenty of e-commerce sites that use either
existing technologies, such as Microsoft products, or
proprietary systems, it seems like there's a large number
of new web startups that are running JSP on their sites.
What sort of percentage of the market do you think JSP claims now?
A: Duane : I have no idea.... Surely there are more ASP
programmers out there, and NT is certainly pervasive (like
it or not). I think that this percentage would differ
dramatically depending on what market segment you were
looking at. It is a whole lot easier, but not necessarily
better, to throw together an ASP site. Developers are
easier to find, and you can hack together something pretty
easily by hard coding scripts into the pages, etc. In the
long run, you end up constantly maintaining pages, writing
the same code over and over again, and having to use
programmers to edit your content.
Mark : With respect to web startups, I think the appeal of JSP
is its inherent flexibility. JSPs provide access to the
complete suite of Java APIs and extensions, are fully
integrated with servlets, operate on a wide range of
platforms, and are supported by a large number of vendors.
These qualities all support the quick response to changing
market conditions that are the lifeblood of an Internet startup.
Q: Looking to the future now, where do you see Java heading? Do
you think Java will continue to make inroads with the server-
side market and eventually topple other technologies like
Microsoft's Active Server Pages? Are there other complimentary
technologies on the horizon, such as J2EE, which you're
particularly enthused about?
A: Duane and Mark - Companies are starting to see the inherent
risks of vendor lock-in. This is why we are starting to see
such a leap to J2EE. Microsoft has a marketing machine
however, and frankly I suspect that a lot of IT and
development managers who don't know anything but the
Microsoft way will happily submit to their captivity. Java
is not just "multi-platform", more importantly its
multi-vendor. At my company, we don't even like to tie
ourselves to a particular servlet engine or application
server. We want to be able to switch suppliers when
something new comes along or they can't meet our
requirements.
Thanks Duane and Mark for talking to us about JavaServer Pages,
and related technologies. Their book, Web Development with
JavaServer Pages, is published by Manning, and covers JSP 1.1,
the latest release.
=================================================================
Interview with Ed Roman, on Enterprise JavaBeans
Ed Roman is one of the world's leading authorities
on EJB and J2EE. He is the author of Mastering
Enterprise JavaBeans and the Java 2 Platform,
Enterprise Edition, an advanced book on EJB and
J2EE development. He is also CEO of The Middleware
Company, a firm specializing in EJB training and
consulting.
In this exclusive interview, we talk with Ed about
EJBs, and web development with the Java 2 Enterprise
Edition platform.
Q: What do you believe has been the biggest change affecting the
Java community in the last year?
A: The biggest change is Microsoft's decision to drop Java in
favor of C# (pronounced "see-sharp"). C# has a chance of
becoming the de-facto programming language for Win32-only
applications, just as Java has become the de-facto
programming language for cross-platform applications.
Another noteworthy advancement in technology is Microsoft's
.NET initiative. There are some powerful ideas in their new
architecture, and if Microsoft can execute on their
promises, .NET will definitely give Java a run for its money.
It's going to be an interesting battle ahead.
Q: How do you find Java stacks up to other programming languages,
such as C++, for designing large-scale enterprise applications?
A: Java is my top pick. Why? Because:
* Java has built-in security, networking, and threading, all
essential for enterprise-class applications.
* The virtual machine model, along with garbage collection,
means applications are more reliable and less error-prone.
* The fact that Java is divided into 3 platforms (J2ME, J2SE,
and J2EE) means different markets benefit from different
flavors of Java.
* Enterprise-class applications are often written by ISVs which
don't control their deployment environment and require
cross-platform development.
There is incredible momentum behind Java. Most developers are
hungering to get on Java projects. This means that organizations
adopting Java are likely to have an easier time finding good
developers in the future.
Q: For the novice, what exactly are Enterprise JavaBeans? How do
they fit in with other Java technologies, like JavaServer
Pages and Servlets?
A: EJB is the cornerstone of server-side Java. You wouldn't use
EJB for embedded devices or desktop applications, you'd use it
for the hard-core business logic and data logic required for
large-scale multi-user applications. EJB is tied together with
JSP, servlets, and other server-side Java technologies via the
Java 2 Platform, Enterprise Edition (J2EE) specification. You
can think of EJB as a subset of J2EE. The rest of J2EE provides
the glue and missing puzzle pieces to built complete web sites.
Q: While it's still early days yet, have you seen any successful
EJB/J2EE projects?
A: Absolutely. My company has helped clients develop and deploy
EJB systems used for a variety of tasks. These include:
* Rating financial bonds
* Performing online procurement
* Coordinating with airplane navigation equipment
* Mapping the human genome
* Performing workflows to process orders
* Managing telephony switches
* Performing banking transactions
Q: That's an impressive list of tasks. What methodology do you
recommend companies take to develop successful EJB systems?
A: We've devised a 4-step procedure to getting EJB projects
started on the right foot. These steps include:
1. Training your staff on the technologies. By educating
your developers in a controlled environment, they can
learn in days what would normally take weeks or months.
2. Design work. This includes analyzing business
requirements and mapping those into a reusable EJB
architecture. The Unified Modeling Language (UML)
should be used for all diagrams.
3. First-pass development. I strongly encourage firms to
consider an iterative development process, where they
divide their design into 'slices' of EJBs, JSPs, and
servlets, and build a complete slice first. This
re-usable slice is demonstratable to management
and/or investors, and can be used to perform
scalability testing before the entire application
is developed.
4. Selection of an EJB server. To choose the right
application server, first come up with a short list
of 2-3 vendors you're choosing from. Then bring
those vendors in-house, and deploy your first-pass
into each of those vendors' application servers.
This empowers you to evaluate how they handle your
specific needs.
You can find out more about this process at
http://www.middleware-company.com/quickstart.html
Q: What would be the best development tool for an EJB developer?
Which server do you think stands out from the crowd?
A: My preferred tool is Visual SlickEdit because its simple and
fast. However, that is not an EJB-specific tool. There are
some newer tools that are emerging that dwarf SlickEdit when
it come to EJB functionality, and they include IBM's
VisualAge for Java, Inprise's JBuilder, and WebGain Studio.
Q: The complexity of the Java 2 Enterprise Edition platform,
and technologies like Enterprise JavaBeans, makes for a
steep learning curve. In what way does your book assist
developers in understanding and learning EJBs?
A: My book explains EJB by first explaining the technologies
that EJB depends on: RMI, JNDI, RMI-IIOP, and XML. So you
only need to know Java to understand EJB. You can download
a complete electronic copy of the book (in PDF form) from
http://www.TheServerSide.com, or order a print edition from
all good bookstores.
Q: Looking to the future now, where do you see Java heading?
Is there a particular technology that you're enthusiastic
about?
A: I think the most important technology that the Java community
should keep an eye on is the Simple Open Access Protocol
(SOAP) along with XML. In the future, many web sites will
be constructed in a piecemeal fashion from other web sites
that they subscribe to, and SOAP enables this to happen.
Q: Ed Roman, thanks for talking with us. You can order Ed's book,
Mastering Enterprise JavaBeans and the Java 2 Platform,
Enterprise Edition, from all good bookstores, or online
from Amazon.com.
http://www.amazon.com/exec/obidos/ASIN/0471332291/davidreillysprog
=================================================================
Q&A : What does a void return value mean? Which class
is being returned?
You've probably heard of this method :-
public static void main(String args[])
before.
It's invoked by the JVM when starting a Java application. Have
you ever wondered why it didn't have a return statement at the
end of the method? After all, don't all methods return a value?
It's possible, and actually quite common, to not return a value.
If you're not going to return a value, however, you must mark
your method as void. This tells the compiler there's no need to
enforce a return value.
=================================================================
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