Flow and Transport Models, Soil Physics, Oklahoma State University
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| Java Web Start and Java
Applets
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We have chosen to develop this interactive software using the Java programming language introduced by Sun Microsystems. It is an excellent object-oriented language that is well suited for use on the internet and for integrating with database applications. In 1998, we began developing the programs as Java applets. This technology allowed us to place the program on a web server and users could run the programs on their local computers by means of a web browser. Most browsers support the Java language so the applets could be run on most personal computers without installing any plug-in or other software. As the language progressed, it became apparent to Sun that subtle differences in browsers could cause undesirable behavior in the applets, primarily in the user-interface. To overcome this problem, Sun developed and distributed a Java plug-in so applets using the plug-in would operate uniformly across web browsers. This technology is still available. One disadvantage of this approach is that the user must download and install the plug-in before the applet can use it. As our software became more sophisticated, we soon wanted to use printers and disk drives on the local computers. The security methods used to protect user's computers made this difficult. At the same time, the applets suffered from the need for a user to be connected to the internet in order to run the program. Frequently that was very difficult or impossible. About 2000, Sun released the Java Web Start technology and we made the move to that platform. This new technology still requires the user (except for Mac OS X users) to install the Java runtime environment and Web Start package. These are available free of charge and in the latest version, come in one installation package. Once that installation is completed (usually in less than 5 minutes in Windows systems) the Web Start programs can be used in the same way as applets but without the limitations of applets. That is, when a user finds a program on a web site (such as the one here) he or she wants to use he or she clicks on the link to the program. If this is the first time the program has been accessed, the software are downloaded automatically to the user's computer and a window outside of the browser opens and the program can be used. Because the program is stored on the user's computer, it can be used at a later time even if the computer is not attached to the internet. The Web Start applications can access local disks and printers attached to the user's computer so that limitation of applets no longer exists. In order to protect the user's computer from damaging programs, the user must grant permission to the software to use these resources. Another nice feature of the Web Start technology is the automatic updates. When a computer is attached to the internet and the user starts the program, the software searches the web server from which the software was obtained to see if the software and associated data have been updated. If more recent software or data exist, these items are automatically downloaded and used. If not, the copy of the software on the local machine is used. This enables users to have the latest version of the software and data. (This technology is used in our PEET decision-support system to keep the herbicide treatment data current for users.) Because we see many advantages in the Web Start platform, we are utilizing it in our current software. Some applets are still available at this site, but those programs are not updated regularly. All of the software available in applet form here is also available for Web Start. More are in testing and will be released soon. We encourage you to use the Web Start software. |
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