Graphic web applications using java servlets, applets and database technology

Ronald D. Ray
National Climatic Data Center

NCDC recently has installed a Linux based PC Web Server environment, and I began developing software to run in this new environment. JAVA was the programming language of choice and 2 specialized JAVA Classes were needed to handle certain aspects of Web Application development.

JAVA Servlets serve the same purpose as most any other CGI scripting language, they return HTML to the user's web browser. Servlets are compiled code and execute very fast on the Web Server. Servlets are used to create the user interface, accept inputs, query the database using SQL, and return the data and html to the browser.

JAVA Applets are called by the servlets when a graph needs to be plotted. Applets are also compiled code and execute fast. The applet code is returned (along with the HTML) and executes in the user's Web Browser. Data needed by the Applet (to be plotted) is passed through a parameter clause in the applet markup code. A graphic region is defined and the needed graphic routines are called to plot the graph. The Java AWT toolkit contains the methods used in these examples, and provides complete flexibility for creating customized graphic displays.

The demonstration will consist of displaying Web Applications that have been built using JAVA Servlet/Applets, and a number of different graphs showing the flexibility of the JAVA AWT Graphic toolkit.

BIO -Ronald Ray Ron Ray has worked as a applications programmer for NCDC for the past 10 years. In the early 90s, Ron worked on large database applications running on IBM workstations that ingest, quality control, produce publications and archive data received from Automated Surface Observing Stations(ASOS). The last few years, Mr. Ray has been involved with developing web applications, that access Oracle Databases, displays data and plots graphs using JAVA Servlets, Applets and Scripts.

Auditorium - Paper Thursday, 1:20 - 1:40 P.M