We propose a multi-platform framework for easy development of applications that share live or recorded data of any type in a classroom. It is especially aimed at training in the medical area, where it can make the learning process much more interactive and enriching, but is equally well suited for use in any type of workshop, tutorial, or other learning environment. The framework is browser-based, for better portability. In order to scale well to a large audience, the framework uses multicast for communication. It provides configurable reliability that is adaptable to data flows with different requirements, real-time or not. It also provides security, privacy and access control features that are necessary in medical training environments. Finally, it allows session discovery and management, and multi-sender support.