CUMULVS is a software infrastructure for the development of collaborative environments. It supports interactive visualization and remote computational steering of distributed applications by multiple collaborators, and provides a mechanism for constructing fault-tolerant, migrating applications in heterogeneous distributed computing environments.

CUMULVS contains a library for scientific applications that provides computational steering control, as well as visual feedback that a scientist can intuitively analyze. The library consists of approximately 20,000 lines of C code. Tcl binding: [1]. The CUMULVS distribution includes a standard Tcl/Tk slicer and a sample custom Tcl/Tk viewer for a particle-based simulation.

CUMULVS provides:

• Collaborative On-Line Visualization of Remote Simulations through Multiple Viewers Connecting to a Running Application.
• Coordinated Computational Steering Among Several Collaborators.
• Automatic Recovery of the Virtual Environment to Host or Network Failures.
• Fault-Tolerance of Distributed Simulations through Heterogeneous Task Migration and User-Directed Checkpointing.
• A Monitoring System for High-Performance Scientific Simulations.
• Dynamic Viewer Attachment / Detachment.
• Message-passing over wide-area ATM networks between multiple MPP and SMP systems.
• Secure and authenticated data transfer.

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