the styling interface

The data entry interface for the menubuilding app

I’ve gradually been developing my menu building application into a distributed web system. It uses OpenLaszlo for the building front-end, java & jsps for the database storage and retrieval facilities and OpenLaszlo to correctly display the menu from provided settings.

Here’s a few screenshots to spice up this at times rather bland blog!

Some nice features to note:

• dynamic data entry facility with ability to add and remove data as desired (I’d hope to standadise it into a generic ‘data entry’ class so it can be reused under different circumstances).
• color swatch components with preset colors to select as well as RGB color pickers
• dynamic example that updates as styling options are chosen

Plus, while I can’t easily show it, there’s a little bit of animation involved too.

I hope that any developers out there looking to make use of OpenLaszlo find this article useful, and by all means do reproduce it, keeping mindful of the Creative Commons licence on all of the work found on this blog.

http://blog.ssims.co.uk/index.php/deploying-openlaszlo-applications-a-crash-test-manakins-guide/

• OpenLaszlo apps are written in the LZX programming language, which is XML based
• They run on the Laszlo Presentation Server (LPS) which is a web application itself that will run on servlet containers such as Apache Tomcat as well as other application servers.
• You can develop programs live on your development machine by running the OpenLaszlo Server and surfing to the localhost 127.0.0.1:
  http://127.0.0.1:8080/lps-4.3.0/my-apps/

All LZX programs have a <canvas> element and generally built of one or more <view> elements:

<canvas>
    <view><text>Hello, world!</text></view>
</canvas>

It is an object oriented language so you can develop new types of components using the <class> tag and this allows for inheritance e.g. <class extends=”view>

This should get a few people started with it, once you have the server up and running I fully recommend you take a look at the OpenLaszlo Explorer which opens when the server is started. It has a huge number of sample applications and makes it so easy you needn’t have any programming experience whatsoever to develop simple apps. That’s pretty exciting if you ask me! Of course, the more advanced features require a good understanding of web software. But the simplicity of learning the language might bring a more diverse range of developers to the table.

That’s all for now, later I will document deployment of OpenLaszlo applications as it isn’t hugely evident in the guides and I’ll also touch on integration with Java applications.

I further intend to deploy the project as a full OpenLaszlo application which will allow for the creation of dynamic menus. There are many ways to facilitate this two way communication with a Laszlo application, and due to the XML structure of the data and styling used in this menu project it will be simple to implement.

I have chosen to develop an XML generating Java Server Page (JSP) which takes various parameters and creates the desired settings. I’ll then call this page from a server side app (probably Java based) which allows the user to chose various settings and downloads the XML itself and puts it directly into a database saved under a certain name. The menu when run can then retrieve the settings of a given name from another JSP page which retrieves the XML from the database.

E.g.  User changes settings & saves –> Java program creates XML from JSP & stores in database –> User choses to view a saved setting –> OpenLaszlo menu app sends query to JSP which creates XML from database stored XML –> Menu is displayed

Which all sounds a bit confusing but will basically allow for a user to create their own menus with unique headings, links and styling, save their settings and even download the compiled flash SWF.

This sort of rapid development from a simple menu into a menu building tool would not be possible if it wasn’t for the excellent structure and maturity the OpenLaszlo LZX language posesses. It naturally encourages modular program design without even requiring you to make a conscious decision about hown to develop a program. The allowance for object oriented classes means that you can develop versatile components, and there are many pre-existing components that can be built upon. For example in this instance, my text sizing component could be added to a library and easily deployed in a multitude of different applications.

I’m very impressed with the platform itself and even the support of the OpenLaszlo community forum which was useful when I was stuck with how to approach certain aspects of the program. In my humble but considered opinion, JavaFX would have to come a long way to surpass OpenLaszlo and as for Microsoft Silverlight and Adobe Flex – what more can I say than why pay?

It is also worth noting that the first OpenLaszlo release was before that of all the major RIA platforms. Obviously due to the open source nature of the project it needed some work, but it speaks volumes for open source development that we are now looking at a very well developed platform for developing and deploying Rich Internet Applications.

Programs in OpenLaszlo are written in XML style syntax and it offers multiple ways of deploying applications in both Adobe Flash and DHTML formats. The possiblities for integrating OpenLaszlo applications with other server side technologies and the overall sophistication of the architecture make it an excellent contender for use in web systems that require advanced user interface features.

As the name suggests it is an open source platform and development of it started in 2001. It is now a mature development environment and has been used to develop many sophisticated commercial applications such as LaszloMail (a webmail system).

Having been testing it for a short time, I can see there are some obvious selling points. Due to the XML style syntax used in the programs you develop with it, there is seemless integration with XML data, unlike JavaFX which requires use of their provided XML parser to obtain data from XML sources. In fact in OpenLaszlo a <dataset> tag is supplied for easy binding of XML data into your application. This essentially makes it simple to provide dynamic user interface features, which would allow for example customisable interfaces.

I expect the platform will personally be useful for developing sections of sites that require more advanced UI elements, and in some instances fully dynamic pages. So far I’ve found the syntax very straightforward to learn and generally quite intuitive. At some point I’ll look at how best to integrate OpenLaszlo features or pages within a J2EE context.