Laszlo

Today's focus: Building sophisticated Web apps the open source
way
By Mark Gibbs
About a zillion years ago (actually it was April last year, but
we're talking Web time here) I wrote about Laszlo Systems and
its Laszlo Presentation Server for delivering Rich Internet
Applications (RIA) - see
.
Since those far-off days, Laszlo have made a bold change in its
business model: It has gone open source. Laszlo Presentation
Server as of October last year became OpenLaszlo (
) under the Common Public License (
).
What's more, Laszlo has re-engineered its system so that RIAs
created with the OpenLaszlo XML-based interface definition
language, called LZX, can be delivered either from the
OpenLaszlo server (OLS) or compiled by the OLS and delivered by
a regular Web server. The latter deployment is called "SOLO"
(Standalone OpenLaszlo Output) and can be used as long as the
RIA doesn't rely on media types other than SWF, JPG or MP3;
persistent connections; SOAP; or XML-RPC (once installed you can
find a discussion of PLS vs. SOLO deployment at

).
LZX is essentially a meta-description of Flash objects, and the
output is a Web page with Flash content (
). OpenLaszlo's
objects are visually elegant and functionally well-designed,
which give the LZX-created RIAs a highly professional look and
feel - you can see the demos page at
.
Version 3.0 OpenLaszlo server has a long list of features
including the ability to create virtually "instant" starting
RIAs using Laszlo's optimization system called KRANK (

). OpenLaszlo 3.0 includes a new drawing API and dynamic
libraries that allow developers to minimize the application's
initial download size and then transfer only the portions of the
application the user invokes.
OpenLaszlo is written in Java and requires Java Runtime
Environment (JRE) 1.4. The OpenLaszlo Developer Kit requires the
Java SDK with the Jakarta Tomcat applet server - in other words,
only freeware is required (see
for a useful
architectural diagram).
Now you might take a look at LZX and think why isn't there an
Integrated Development Environment for this? Well, apparently so
did the chaps at IBM so they created an Eclipse (
) plugin for OpenLaszlo (
).
The combination of OpenLaszlo, Eclipse and the IBM plug-in take
building RIAs up a level. Definitely worth checking out if you
are building sophisticated Web applications.
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