Java applets are downloaded from Windchill servers and executed on the client system. They provide sophisticated graphical user interface functionality, allowing for complex interactions with the user.

Once running, the applets communicate directly with Windchill servers via Java RMI. This avoids the additional overhead of communicating indirectly through the HTTP server and allows for very complex data to be passed easily between client and server.

If it is necessary to get through firewalls by using an HTTP proxy, Java RMI communication is automatically layered on HTTP. However, this results in greater performance degradation than a direct connection to a Windchill server.

Applet classes loaded from the same Windchill system communicate with one another to use the browser windows and frames, presenting a seamless system image.

Applet classes loaded from federated Windchill systems (coming from separate HTTP servers) cannot communicate directly with one another for security reasons. Intersystem links are therefore accomplished using HTTP URLs, given to the browser for loading into HTML windows. The resulting HTML pages contain JavaScript/JScript and applet tags that use windows and frames to present a seamless system image.

Interactive applets can present feedback on behalf of long-running server transactions. This feedback can take the form of progress indicators and, in some cases, provides the ability to cancel the operation.