Panasonic FP Web-Server, User Manual

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Java Applet Library "MEW.JAR"
FP Web-Server V2.11
158
14.1 Introduction to FP Web-Server and the Java Applet
"MEW.JAR"
Enhance your HTML Pages with Java Applet Windows:
The Java Applet technology can be used for complex,
high-speed, dynamic PLC data visualization in Internet
Browser windows. Java applets can help to improve your
HTML pages. You only need standard software, the
MEW.JAR Java Applet Library and minimal HTML design
knowledge.
General:
Java Applets are user application programs written in the
programming language Java. These programs are stored
together with the HTML files in the Http-Server section on the
FP Web-Server unit. The Java Applet file has the file
extension .JAR (Java Archive). An Internet browser and a
special tag within your HTML page are needed to download
the .JAR to the computer. The Java Applet program is then
started by the Internet browser and runs on the computer in a
secure area ('Sandbox'). Each Java Applet has its own
window which can be freely resized and positioned within
your HTML page. Parameters within the HTML page can be
used to configure the Java Applet functions.
Java Applets Compared to HTML and Java Script:
Normally web pages are designed by using HTML and Java Script (DHTML) code, which allow
only very limited dynamic features to be implemented. Moreover, DHTML is not very fast and is
not compatible with the various Internet browsers. The programming language Java, which is
used to design Java Applets, is a powerful, future-oriented tool for programming huge
applications. Java code can run on various computer systems, e.g. Linux and Solaris. Java
code runs in a separate, secure area and hence cannot compromise the computer.
The Java Runtime System:
Java program code cannot be executed directly by the computer's CPU (Windows, Linux,
Solaris...). Java code is a kind of intermediate or meta code and needs a special software to be
interpreted and executed. The required Java interpreter software from the company SUN is
called 'Java 2 Runtime Environment', or in short 'JRE'.
For more information on the Java Applet Library, please refer to the online help under
the keyword "Java Applet Library" or to the pdf file "JavaAppletLibrary.pdf" on your
installation CD-ROM in the sub-folder "JavaApplets".