FAQ & Support

Java Web Start is not among the applications in the browser's prompt

You don't have Java Web Start properly installed. The following tips may help you to fix the problem.
  1. Check that you have Java Runtime Environment (JRE) properly installed. You can do it by entering "java -version" at the command line. It should output installed Java version. If not, install the last release of JRE from Java download page.
  2. If you have properly functioning JRE, then Java Web Start is not properly configured to your browser. Please see Java Web Start FAQ for instructions on how making your browser recognize JNLP files.

Java: "Application Blocked by Security Settings"

With version 1.7, Java is proposing a completely different signature mechanism to authentificate the publisher of an application.

To allow Jmod to start, open Java configuration > Security tab and either:

  1. add "http://tschaffter.ch" to "Exception Site List" (preferably)
  2. set the security level to medium

To open Java configuration, click on Windows/Linux start menu icon, enter "java" in the search field, and click on "Configure Java".

Java Web Start Launcher complains: "Could not create the Java virtual machine"

Typically these issues are because of memory settings. Some new Java Runtime Environments have become picky about them and refuse to start. You can try the alternative startup link that has no memory requirements by clicking here. The negative effect of the alternative link is that the application is limited to only small memory usage and can be slow.

Autostarting Java Web Start applications

By default, Google Chrome downlads the startup JNLP file after clicking on the button "Launch Jmod" and requires an additional click on this file to run our application. To start automatically Jmod, Right-click on the JNLP file downloaded by Chrome > Always open files of this type.

There is no simple way to enable autostart of Java applications in Safari. Also, Safari doesn't show immediately a link to the files dowloaded. Either click on the Download button (see image below) or open your Downloads folder before executing the JNLP file (JNLP files must be associated to Java Web Start via Right-click on the file > Get Info).

Internet Explorer and Firefox should no problem autostarting Jmod.

"Not Responding" on Windows

This issue may be solved by increasing the maximum heap size (memory) of the JVM (see below).

Allowing Jmod to use more memory (Java Web Start)

By default, Java only allows applications to use up to 250-300 MB of memory. In addition, memory requirements must be define before launching an application and if the requirements are not satisfy, the application won't start. Thus, Jmod doesn't make any memory requirements by default.

If you have access to a 64-bit operating system, a 64-bit Java installation and enough physical memory, you can use the 1GB, 2GB or 4GB version of Jmod (click on the link to launch Jmod).

You can also specify custom memory requirements by downloading one of the JNLP files below (Right-click on the link > Save as), opening the file with a text editor and changing the value after the parameter -Xmx (e.g. -Xmx2000m to allow Jmod to use up to 2 GB of memory).

Creating desktop shortcut fails (Java Web Start)

Due to some issue with Java Web Start and/or Mac OS X, creating shortcuts fails on some environments. As this happens before our application starts, we unfortunately cannot do anything about it. To launch Jmod next time, you can either:
  1. On the Jmod website, click on "Launch Jmod" on the right side of the page
  2. Download the Jmod JNLP file and use it as shortcut
  3. Open "Java Preferences" and locate the list of downloaded Java applications

Creating a desktop shortcut on Windows (Jmod standalone)

If you downloaded the standalone version of Jmod (JAR file), the instructions below show how to setup a desktop icon to run the graphical user interface (GUI) of Jmod.

  1. Right-click on jmod-1.2.2b.jar > Create shortcut
  2. Right-click on the shortcut > Properties
  3. Add "--gui" (without quotes) at the end of the field Target

You can use this icon file (or this icns icon for similar operation on mac) to change the appearance of the shortcut.

Increasing Java maximum heap size (Jmod standalone)

Opening and running a community detection algorithm may require large amount of memory (heap size). This is particularly true if multiple networks are analysed at the same time. By default Java limits the quantity of memory available to an application. First, check the amount of physical memory installed on the computer. To increase the Java maximum heap size, use the JVM option "-Xmx2048m" (without quotes), for example:

java -Xmx2048m -jar jmod-1.2.2b.jar --gui

Here the maximum heap size is set to about 2 GB (2048m). Note that the theoretical maximum heap size limit that can be set to a 32-bit Java Virtual Machine (JVM) is 4 GB. If the heap size value specified is above or to close to the amount of memory installed, the error message "Could not create the Java virtual machine" will be displayed.

On Windows, the JVM option -Xmx2048m (or any other value) can be specified in the field Target from the properties of the shortcut.

On Mac OS X:

  1. Go to the Applications folder
  2. Right-click on Jmod > Show Package Contents
  3. Open the file Contents/Info.plist with TextEdit

Then add or complete the tag VMOptions before saving the file Info.plist.


"Not Responding" on Windows

This issue may be solved by increasing the maximum heap size of the JVM (see above).

Jmod doesn't function properly

Please submit an issue or contact .

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