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Installing OpenLaszlo

From OpenLaszlo

This page provides instructions for installing OpenLaszlo:

  • Installing the OpenLaszlo Development Kits (RECOMMENDED)
  • Installing the OpenLaszlo Servlet
  • For detailed instructions for building OpenLaszlo from source (see SubversionBuildInstructions)


Installing the OpenLaszlo Development Kits

OpenLaszlo Development Kits are binary distributions with installers for specific platforms that include the Tomcat 5.0.24 servlet container. Development kits (DevKits) also include the documentation, sample code, demonstrations, and Laszlo in 10 minutes tutorial code.

OpenLaszlo has development kits that can be installed on Windows, Unix/Linux, and Mac OS X.


To run OpenLaszlo, you must have the Java SDK (sometimes called the JDK, J2SDK, or J2SE SDK), not just the JRE, 1.5 or greater. It's available at:

Note: Mac OS X users do not have to install the SDK, as it is installed with OS X by default.

Installing the DevKit on Windows

To install the OpenLaszlo DevKit for Windows, do as follows:

  1. If you already have a copy of Tomcat (or any other service that is running on port 8080), please make sure that it is stopped.
  2. Download the OpenLaszlo DevKit for Windows on the site:
  3. Run the installer executable, which will be called something like: openlaszlo-4.9.0-windows-dev-install. If you don't have Java SDK installed, you will be prompted to download it; follow the onscreen directions.
  4. When the installer is complete, your browser will open Laszlo Explorer:


To learn how to run programs in OpenLaszlo, see Running OpenLaszlo.

Installing the DevKit on Mac OS X

To install the OpenLaszlo Server:

  1. If you already have a copy of Tomcat (or any other service that is running on port 8080), please make sure that it is stopped.
  2. Download the .dmg file by going to:
  3. Save the file (for OpenLaszlo 4.9, this file is openlaszlo-4.9.0-osx-dev-install.dmg).
  4. Double-click the .dmg file to install it.
  5. Double-click the .pkg icon, and follow the steps to complete the installation.


OpenLaszlo Explorer will automatically open: Image:Olexplore.png

You should now proceed to Running OpenLaszlo.

Installing the DevKit on Unix/Linux

To install the OpenLaszlo DevKit for Unix/Linux:

  1. Download the OpenLaszlo DevKit for Unix/Linux here:[1].
  2. Use tar zxvf to unzip and untar the distribution from /usr/local or wherever you want it to go; you can even use your home directory for safety.
  3. For SWF10 development on Unix, you will need to manually chmod 755 all the binaries in WEB-INF/server/bin/ before you can compile. This is true for both the .war and .gz distributions.
  4. Don't just copy the Tomcat folder into /usr/local. Keep the whole distribution together. So if you put it in /usr/local, it would look something like this:/usr/local/lps-4.8.1/ with Server/tomcat-5.0.24 as a subdirectory of lps-4.8.1.
  5. Make sure that JAVA_HOME is set correctly. If the instructions below don't work, see the instructions that come with the Java SDK.
  6. Check which version of java you have by typing: $ echo $JAVA_HOME and you should see something like: /usr/java/j2sdk1.4.0 if not, type: $ which java to find Java on your machine. If no value is returned, check the installation of Java as follows. Export JAVA_HOME by typing: export JAVA_HOME=(location of Java on your machine) and you should see something like: /usr/java/j2sdk1.4.0
  7. Make sure that you have the version 5 or greater of the Macromedia Flash browser plugin installed.
  8. Run the /lps-4.8.1/Server/tomcat-5.0.24/bin/ script, and you're ready to go. This script will set the following environment variables:
            JAVA_HOME - note that JAVA_HOME must be set before running the script
  9. Test your installation:[2].
  10. Click on the link to hello.lzx, and it brings you to http://localhost:8080/lps-4.8/examples/hello.lzx[3]

Linux Notes

On some installations of RedHat 7.2 Linux, you may need the XFree86-libs RPM from

In order to access JSP pages, you may need to copy $JAVA_HOME/jre/lib/tools.jar to lps-4.8.1/Server/tomcat-5.0.24/common/lib.

Installing the OpenLaszlo Servlet

The OpenLaszlo servlet package contains only the servlet, the smallest set of files required to deploy an OpenLaszlo application on any OS running Java. It is recommended that you only proceed with deploying a servlet if you are experienced with containers and the security issues when deploying.

Contents of the Servlet Distribution

The servlet includes:

  • LICENSE.txt - the end user license agreement for OpenLaszlo
  • README.txt - a file listing the contents of the distribution
  • 3rd-party - the servlet jar file
  • 3rdPartyCredits - licenses and acknowledgements for 3rd party contributions
  • lps - expanded directory containing the requirements of the application that visible to users via HTTP
  • WEB-INF - everything the system needs to run the servlet, but is not visible to the user over the web
  • my-apps - a directory to store your application
  • release-notes.html - Release notes for the current release

Installing the Servlet

  1. Download the servlet distribution at
  2. Deploy the lps-4.9.0 web application and surf to: http://yourhost:yourport/lps-4.9.0/index.html

where yourhost:yourport is the host and port where your servlet container is running. This should bring up the Laszlo Quick Index page with links to tutorials, examples, sample applications and more.

Notes and Issues for the Servlet


The LPS may not operate correctly if you have a copy of jython.jar installed in: $JAVA_HOME/jre/lib/ext (%JAVA_HOME%\jre\lib\ext on Windows).

WebSphere Installation Issues

Some documents in the lps-4.9.0 web application may be reported 'Not Found' because WebSphere doesn't properly redirect URLs that end in directory names. If you run into this problem, you can use the Laszlo web-site documentation at

WebLogic Installation Issues

As of this writing, WebLogic comes bundled with a version of Apache's Xerces (a XML Parser) that is not compatible with LPS. Though a working version exists in the WEB-INF/lib directory, WebLogic doesn't look in there first by default. To ensure that the WEB-INF/lib/xerces.jar file is picked up:

  1. If you have WebLogic Server or lower on your computer, be sure you DO NOT ENABLE the PreferWebInfClasses flag for your Web application
  2. If you have WebLogic 7.0 Service Pack 1, be sure you DO ENABLE the PreferWebInfClasses flag for your Web application The PreferWebInfClasses flag may be enabled by opening up your "WebLogic Server Console" and under the LPS web application deployment page, click on the "Configuration" tab and then click on the "Other" tab where you'll find the "Prefer Web Inf Classes" checkbox. Make sure you apply your changes and restart the server. You may also choose to directly modify your config.xml file and set PreferWebInfClasses="true|false" or modify your start script's CLASSPATH to pic up the correct xerces.jar file.

For more information on WebLogic and Xerces, consult: Tomcat Installation Issues

If you are using your own installation of Tomcat and you have modified the set of jars, you need to make sure that the commons-logging.jar is not in the java endorsed list of jars.

If you are using your own installation of Tomcat you will need to you will need to copy $LPS_HOME/WEB-INF/lib/jing.jar to $TOMCAT_HOME/common/lib

Linux Notes

On some installations of RedHat 7.2 Linux, you may need the XFree86-libs RPM from

Caucho Resin Installation Issues

Under Resin 2.1.x, you will need to set the resin configuration parameter, servlet-classloader-hack, to true in $RESIN_HOME/conf/resin.conf.