Java Web Start
by Benoy Jose
The Internet revolution took the ordinary user
to the web and they expected the same things
as in their
desktop programs. Java
capitalized on the initial wave with its novel concept of Write once Run
anywhere, which was a perfect fit in the Internet world where the software
could be run on any platform without any change. The internet grew
in popularity and at first, users accepted the limitations of the internet bandwidth and settled
for simpler applications that could not do the trendy things done by desktop
applications. Soon, however, users wanted faster applications. Java as an Internet client
faded away due to its bulky size and slow downloads.
However java retained its
position as a leader in the lucrative application server market with its
proprietary EJB, JSP and servlet technologies. Having established a reputation
as a secure and robust environment Java has made a comeback into the client
market with a new tool. Java Web Start is the desktop based web client that
gives the flexibility of a desktop application and the robustness of a web
application.
What is Java Web Start?
The name Java Web Start as the revolutionary technology is
misleading. In actuality Java web Start is a reference implementation
of the (Java Network Launching Protocol and API) JNLP specification.
JNLP specification was developed and published by Sun as a result of
the JSR 56. JNLP can be defined as a protocol that enables Java
clients to deploy themselves on the client and run as if they were
local applications. However for purposes of this article we shall discuss
Java Web Start.
How is this different from what java introduced earlier as applets?
Java applets were what Sun promised the world as a revolution. But
after the initial interest of seeing animated pictures on the internet
they fell out of favor for their bulky size and slow execution.
Users generally are not patient enough to wait for an applet to load
from the network, check security permissions and then see the information.
If the applet happens to be in swing the wait is doubled. JNLP has
overcome many of the difficulties of applets.
Java Web Start is a JNLP client that allows java applications to be
downloaded onto the client machine and runs them in the Java security
Sandbox. So Java Web Start is a reference implementation provided by
Sun to show the features of JNLP which allows a
developer to create java applications that can be run on a client
without any installation procedures.
Java web start brings in all the security of the java sandbox which
means that you can run an application with the confidence that it
will not over step and meddle with files on the client machine. It
also brings the flexibility of using java applications with swing or
AWT without the hassle of downloading bulky swing jar files each time
the application is run. Java web start is designed to download all
the files required the first time it is invoked from a webpage.
After the first download the user has the option to include a
shortcut to the application directly on the windows start menu
(option provided on Windows only). Subsequent runs of the
application can be done using the shortcut which would then run locally.
The application can be designed to check for updates on the server to
refresh the existing local copy with the changes made since the last access.
Features
The important features of JNLP are
- It is a Web-based Application Architecture where
applications can run locally using resources spread
over the web.
- It provides for an installation free client
application that can keep itself in sync with the
updates on the server.
- It also provides for a facility to make incremental
downloads and updates over a period of time.
- It offers the flexibility to run java applications on
different versions of JRE. The JRE can be can be
downloaded if the version is not present on the
machine.
- It offers a caching facility which can cache the
application locally on the client which saves time the
next time the application is run on the client.
- Applications can be run offline on the client machine
after they are initially downloaded thereby decoupling
them from the server.
- It offers a secure environment to execute applications
like applets but it also provides flexibility within
the API to do potentially unsecure actions with a
warning to the user.
- The JNLP API and Java Web Start are now part of the
J2SE 1.4 download.
Benoy Jose is a web developer with over six years of
experience in J2EE and Microsoft technologies. He is
a Sun Cetified programmer and enjoys writing technical
and non-technical articles for various magazines
New on the Java Boutique:
New Review:
Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling
API boasts simplicity, ease-of-integration, a well-rounded feature
set, and it's free!
New Applet:
Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA
sequences into three useful formats.
Elsewhere on internet.com:
WebDeveloper Java
Lots of Java information on webdeveloper.com
WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.
ScriptSearch Java
Hundreds of free Java code files to download.
jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.
| 
