OpenLaszlo is a popular RIA technology and even though it is not new, there are many Web developers who haven't heard about it. This is not something to be ashamed of – when you keep in mind how many Web technologies and tools exist, it is not surprising there are technologies you haven't heard of.
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How OpenLaszlo Started
Before Open Laszlo adopted its present name and went open source on October 5, 2004, it was known under the name Laszlo Presentation Server (LPS). However, as you can expect, LPS was never as popular as OpenLaszlo is. The move by the original developer, Laszlo Systems, to turn to the open source development model was a smart one and it made the OpenLaszlo platform really popular. At present Laszlo Systems still develops the open source platform and together with it it offers commercial applications, modules, support and training for customers.
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OpenLaszlo In Brief
Open Laszlo is a free, open source platform for the creation of Rich Internet Applications (RIA). The three main components of OpenLaszlo are:
The OpenLaszlo compiler. The Open Laszlo compiler turns your source files into a Flash or DHTML file you can deploy anywhere.
The OpenLaszlo Runtime Framework. The Open Laszlo Runtime Framework has the user interface components, as well as components for data binding and network services.
The OpenLaszlo Servlet. The OpenLaszlo Servlet is the component you will use when you need runtime support for SOAP and XML-RPC (and for some additional media types as well).
So, here is what happens, when you use OpenLaszlo. First you need a source file in a .lzx format. This format is similar to XML. After that the OpenLaszlo compiler compiles the .lzx file into a Flash (i.e. a .swf or shockwave) file. Then this swf file is displayed in the browser. This is the basic process in OpenLaszlo and it is known as 'SOLO' mode.
However, 'SOLO' mode doesn't give us access to SOAP communication and the other advanced features OpenLaszlo supports. If we use the swf file we generated together with the Laszlo Application Server( LAS), we get more functionality. The LAS can compile .lzx files, or we can use ready-made .swf files with it. In addition to Flash, LAS can generate DHTML as well.
The Laszlo Application Server is a J2EE-compliant web application and you can install it on Tomcat5. In addition to that, OpenLaszlo can be used with PHP as well. It is expected that soon OpenLaszlo will work on J2ME devices as well.
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How You Can Use OpenLaszlo
Unlike some of the other RIA technologies (most notably Flex2), which are free but are not open source, OpenLaszlo allows you access to its code, so if you have a problem, you can see exactly what in the source code is causing it. OpenLaszlo uses the Common Public License (CPL 1.0) license. This means that you can use it in commercial projects and even with proprietary applications. Of course, there are the limitations that you can't distribute your applications created with OpenLaszlo under a non-CPL compatible license but given the benefits of using Open Laszlo, this limitation is not something to worry about.