DIVE

The Distributed Interactive Virtual Environments project from the Swedish Institute of Computer Science is one of the original attempts to develop collaborative VE.

Allows its participants to navigate in 3D space and see, meet and interact with other users and applications.

Extensive use of Tcl

Provides persistence through the use of a centralised database server

Still under active development, DIVE is a well-known and widely respected toolkit. It is designed around the notion that the environment should serve both for interactions and for developing new material. It makes extensive use of Tcl to provide extensibility and provides persistence through the use of a centralised database server.