FAQ
From OpenLaszlo
Questions about the using the platform and the components should go here. Questions about building and contributing to the platform should go in the Developer_FAQ. Questions about Legals are answered in the Legals_FAQ.
Contents |
What is OpenLaszlo?
- What is OpenLaszlo?
- What are the features and benefits of the OpenLaszlo platform?
- Are there deployed applications?
- Does it scale? A. Yes. Earthlink, Yahoo, and others have deployed Laszlo applications with millions of users. A scalability whitepaper is available from the Laszlo Systems web site.
- Is it mature? A. Yes. The first release of the platform was in early 2003, and it is currently at its third generation. The Behr paint application was deployed in 2002, and has been running continuously since then.
- How is OpenLaszlo supported? A. The OpenLaszlo project is sponsored by Laszlo Systems, Inc., which provides support services for OpenLaszlo and is using the platform in the development of its online communications and e-commerce applications.
- Why should ISV's consider Laszlo?
- What skills does a developer need to create Laszlo applications?:
- Is commercial support available for OpenLaszlo?
Project History
Does OpenLaszlo Support...
- Does OpenLaszlo support unicode? A. Yes, as of OpenLaszlo 3.0.
- Does OpenLaszlo support bi-directional character input for internationalization to Arabic and Hebrew? A. Laszlo applications can not be localized to the Arabic and Hebrew languages. These languages read from right to left, and require both unicode and bi-directional text input. Unicode support is included with LPS 3.0, but bi-directional text input is not supported by Laszlo's currently supported run-time, the Flash Player.
Programming Questions
- What are best practices for developing applications in OpenLaszlo?
- Why do I get a warning after deleting something?
- How do I convert my code to SWF7?
- How do I convert my code to SWF9?
- How do I get more out of the debugger?
- Where can I find a list of known issues?
- How do I know when replication is done (in other words when the last replicated clone has been instantiated)?
- I have a dataset of the type "http" that references an XML file on our server (e.g. http://myhost/test.xml). What do I have to do to get the dataset/model to update if the XML file changes? A. The Laszlo app will not automatically pick up changes to the server-based XML. Your LZX app needs to issue another request for the XML document when it expects content to change. See the DoRequest() method on dataset. http://www.laszlosystems.com/lps-2.2/docs/reference/dataset.html
- How can I get a copy of the schema that includes my class definitions? A. 'lzc --schema myfile.lzx > schema.rng' will produce a RELAX NG file that defines all the elements that myfile.lzx and its recursive includes define with the @<class>@ tag. Trang can be used to create an XSD file from this.
- I want to use OpenLaszlo without the server. Does anyone have an example of sending and receiving data using SOLO? A. It should look identical to using the data API in proxied mode, except you can't get access to HTTP header metadata.
- Is it possible to integrate JavaScript and OpenLaszlo in the following way:I have some objects in Laszlo and I want to access them by external "javascripts". A. There are some facilities for communication with the browser, via the LzBrowser service. You can call a Javascript routine in the browser that way. There is limited capability to communicate the other way, from the browser to the running OpenLaszlo app, via setting attribute values on the Canvas.
- On my development machine the OpenLaszlo Server is running out of memory every second day. Every LZX file that needs to be compiled starts a new thread. After 200 times Compiling my 512MB RAM is over and the OpenLaszlo Server thows an exception such as "Running out of memory ...". A. The recommended configuration for using the server for development is at least 1GB. If you must run with 512MB, you should cut all the *cache.mem* parameters in at least half.
- What tricks were used in the development of Laszlo Mail? A. We are trying to collect them all into best practices, tips and tricks, and performance optimization.
Deployment Questions
- How do I configure IBM WebSphere to deploy the OpenLaszlo Server?
- How do I deploy the OpenLaszlo Server on JRun?
- Why may LPS installation fail with J2EE SDK? A. The J2EE SDK includes the Sun App Server, whereas the J2SE SDK does not. During the J2EE SDK installation process, the user is presented with the option to deploy servlets within the Sun App Server. This option should be declined. The Laszlo platform is not certified to run on the Sun App Server, and there are reports of incompatibilities. Certified application servers are listed at: http://www.laszlosystems.com/developers/download/requirements/
- Is there hosting for OpenLaszlo applications?
FAQs moved from laszlosystems.com
- When and why did Laszlo become open-sourced?
Beginning with Version 2.2 on October 5, 2004, the entire Laszlo platform, including the Laszlo Presentation Server, the LZX language, documentation and associated examples, was open sourced under the Common Public License (CPL 1.0) by the original developer, Laszlo Systems, to establish a free and open platform for rich Internet application development and deployment.
By embracing the open source development community and model, we expect to accelerate the adoption of rich Internet applications on the open web, as well as enhance the quality, performance and feature set of the Laszlo platform. Laszlo Systems will continue to spearhead development of the open source platform, and provide commercial application modules, support and education programs for customers.
- What type of open source license is Laszlo available under?
The Laszlo platform is released under the OSI-certified Common Public License (CPL 1.0). Laszlo uses the CPL without modification. IBM authored this license for general-purpose use by other companies wishing to release their products under an open source license.
The Common Public License is a 'reciprocal' license that provides maximum flexibility for commercial reuse of source code, aims to protect users against broad liability claims, and requires that modifications to the source be made available under terms compatible with this license.
Laszlo chose the CPL because it is a simple, clear and well-written license that allows customers great flexibility in building on the Laszlo platform, such as permitting proprietary applications written in LZX to remain proprietary, but ensures that any contributions to the Laszlo platform itself remain open source and are "given back" to the open source community.
- Where can I download the source code?
The Laszlo source distribution is available at: http://www.openlaszlo.org/downloads.php
- Where can I download the binary executable?
The Laszlo binary distribution is available at:
http://www.laszlosystems.com/developers/download/
- How can I contribute to the Laszlo project?
Visit www.openlaszlo.org to learn about the current process for reporting bugs and contributing to further development. We look forward to collaborating with you!
- My views aren't showing up. Why?
By default, views will be sized 0px wide by 0px high, and 0,0 inside of their parent view.
Try giving them dimensions, coordinates or a background color:
<view width="50" height="50" bgcolor="red" />
- How do I cause views to be aligned vertically?
Use simplelayout:
<view>
<simplelayout axis="y" spacing="5" />
<view />
<view />
</view>
- I have added a couple of TrueType fonts to my application and the application size has grown a lot.
TrueType fonts are large - use them with care: A single font style can be 30-50Kb or more depending on its contents. Regular, bold, italic and bold-italic are all different styles.
Some fonts are larger because they contain more special characters. Others are larger because they were not efficiently compressed. You should keep track of the sizes of fonts that you use in your application.
- Why do my text fields get cut off?
If you bind a text view to data or set its text at run-time using setText(), by default the text field will not resize to fit its new contents, and will clip them if they are larger than it. Either specify a size, or set the resize attribute to true, to have the text readjust its width when its text changes. Beware that the latter is processor-intensive, and might slow your application if you have large numbers of text elements resizing themselves:
<text datapath="foo:/bar/@txt" resize="true" /> <text datapath="foo:/bar/@txt" width="200" />
For text that is not dynamically set (e.g. foo), its size will be calculated at compile time on the server.
- How do I make a view set its resource to a value XML?
Call the setSource() method when the view's ondata event is sent:
<view datapath="foo:/abc[1]/mynode[1]/@imagurl">
<method event="ondata" args="d">
this.setSource( d );
</method>
</view>
The ondata event gets sent when the data that the view's datapath is pointing to changes. There's a special variable (named in the arguments of the method) which will resolve to the data.
- Euro Character
The euro character in the default TrueType font (Verity) does not show up in Laszlo-compiled swf5 applications that embed this font.
This is because the Verity font has the euro character in the correct Unicode location for the euro (0x20ac [#8364]), but the Flash5 player requires embedded fonts to have the euro at a nonstandard location (char code 0x100 [#128] - the location for "Capital C with cedilla").
If you need the euro character in Verity, you can copy the .ttf file and modify it (moving the euro) with a tool, like Fontographer or a developer friendly tool like TTX (http://www.letterror.com/code/ttx/).
Any font that has the euro character at the standard location will surface this issue in a Laszlo compiled swf5 application.
- How does Laszlo’s solution differ from Macromedia’s offerings?
Unlike Macromedia’s rich Internet application platform, which is primarily targeted to designers, artists and multimedia developers, Laszlo’s goal is to meet the needs of developers while delivering applications with superior functionality. Our solution takes advantage of the compact and reliable Flash player (a browser plug-in), but shares nothing else with Macromedia’s offerings. No knowledge whatsoever of Flash authoring arcana is required to build Laszlo applications — an approach embraced by application developers. Laszlo’s solution is a standards-based XML server that integrates into modern IT (J2EE or Java servlet) infrastructure.
