Hints on using Java Web Start Apps

Since a number of people have reported problems installing and running the AAVSO's Java Web Start applications such as VStar, SunEntry, Zapper and SeqPlot, we thought it might be helpful to provide some additional information and tips which we hope will make it easier for you to get started.

What is Java Web Start?

The Java Web Start software allows you to download and run Java applications that are stored on the AAVSO Server. For example, when you go to the VStar webpage on the AAVSO site and click the "Download VStar Now" button, a small text file with the extension JNLP will be downloaded to your computer. This file contains links which will launch the Java code on our server.

Please note:

  • Java Web Start is included in the Java Runtime Environment (JRE) which you will need to install on your computer if you do not have it. A link to the download and instructions for installing can be found here: https://www.java.com/en/download/help/index_installing.xml
  • When you download the JNLP file from the AAVSO website, if your browser gives you a choice between saving the file and opening it, please be sure to save it to your computer. That way, you can use it ro re-launch the program again in the future without having to go back to the AAVSO webpage anymore.
  • Very Important! The JNLP file can only be launched with "Java Web Launcher" (or something like that). It is very likely that the first time you try to open it, your computer's "file association" will be wrong and it will try to open the JNLP file with something else that won't work. If this is the case, right-click on the JNLP file, and select "Open with...". Assuming Java was correctly installed in your computer, "Java Web Launcher" should appear as one of the possible choices.

If all else fails, you can download a .zip file of the program you wish to run and launch it without using Java Web Start. The disadvantage of this way is that it will not be updated automatically when any updates are made.

Useful links

From the Java website:
What is Java Web Start and how is it launched?

For more help

Contact Sara Beck at AAVSO HQ.