Webreference-Getting out of the Sandbox: Building an Applet Proxy Server | 3
There was a reason Sun created the applet sandbox, and any mechanism that makes it easy to circumvent it should be scrutinized carefully for security holes. One possible extension of the server would be to add two protocol commands, USER and PASS, that would accept a username and password and compare them to a database of accepted application "usernames" and passwords. Only approved applets would be allowed to make a proxy request. To keep it simple, the server is also weak on error-checking: if there is a problem connecting to a URL or if a client crashes, the result is usually a dead thread. Too many such crashes and the proxy server goes down. One possible solution to this is running a "monitor thread" that keeps the number of live, running threads at a constant number.
On the applet side, the possibilities are limited by your imagination and your ability to decipher a complicated Web page for nuggets of data. Possible applets include a configurable weather station that gets and redisplays the weather from http://www.weather.com, a more powerful stock ticker that uses a textbox where the user can enter a stock symbol to track rather than a parameter in the HTML, and a headline applet like the ABC news headline ticker at http://home.netscape.com.
The downloadable package contains all of the source code, bytecode and documentation for the proxy server and quotron. It also includes a copy of this article for your reference.
- 1AppletProxyServer.zip (68 k)
Kyle Downey is chief technology officer and a partner in WebConcepts, LLC, a Java and dynamic Website development firm located in New York. He has worked as a Perl, C, C++, and Java programmer at various New York-area Web companies, and as a technology columnist for Intranets Unleashed. He can be reached at firstname.lastname@example.org.
Comments are welcomeCreated: Oct. 27, 1997
Revised: Oct. 30, 1997