Applets can use any communication channel any Java code can use - HTTP, sockets, web services, JMS, email, RMI, ...
Of course, an applet are only allowed to connect to the host where they were served from, so if they need to access some other server then they'll need to be signed, or the local security policy altered. See HowCanAnAppletReadFilesOnTheLocalFileSystem for more details.
Post by:autobot
Stop it! You're embarassing me! And you are embarrassing this tiny ad!
a bit of art, as a gift, that will fit in a stocking