The MR Toolkit Peers Package and experiment

Abstract

The MR Toolkit Peer Package is an extension to the MR Toolkit that allows multiple independent MR Toolkit applications to communicate with one another across the Internet. The master process of an MR Toolkit application can transmit device data to other remote applications, and receive device data from remote applications. Application-speci c data can also be shared between independent applications. Nominally, a n y n umber ofpeersmay communicate together in order to run a multi-processing application, and peers can join or leave the collaborative application at any time. This paper will introduce the peer package, and will explain the theory of its operation. The last part of the paper will discuss our experience with a demo program we h a ve written called multi-player handball that uses the peer package. I n troductionOne of the main research thrusts in the study of virtual environments is to examine how many people can work together on a common virtual application. The basic idea is to allow people who are geographically dispersed to collaborate on some task in one common virtual space. Software that enables this kind of interaction must support both adequate single-person VR style interaction, and must support communications to other computers. The presence or absence of other users in the simulation should have no e ect on the visual presentation, and should not induce undue lags or delays in the interaction.The MR Toolkit Peer Package is an extension to the MR Toolkit 7, 6 ] that allows multiple independent MR Toolkit applications to communicate with one another across the Internet. The peer package allows the master process of an MR Toolkit application to transmit device data to other remote processes, and to receive device data from remote processes. Application-speci c data can also be shared between independent M R Toolkit applications. Nominally, a n y n umb e r o f p e e r s m a y c o m m unicate together in order to run a multiprocessing application, and peers can join or leave the collaborative application at any time. Thus, the peer package allows each user to have a smooth interaction with the virtual environment, while updating each remote peer with the local device data. Previous WorkThe most famous example of a multi-user virtual environment is SIMNET 1], which i s a n i n teractive network system for real-time person-in-the-loop battle engagement simulation and war-gaming. SIMNET uses wide-area ethernets and satellite links to join hundreds of independent s i m ulated components such a s

A taxonomy for networked virtual environments

“…For example, the MR Toolkit Peer Package, which is used for creating distributed virtual reality applications over the Internet, uses unicast for communications among the applications though the developers have considered using IP Multicast [29]. Unicast is also the general approach for Grand Challenge applications like MAGIC.…”

“…DIVE uses the concept of process groups from ISIS to partition the VE into rooms or spatial regions. The MR Toolkit distributes processes that support different components of the VE such as the input devices [29]. It provides an interpreted language, the Object Modeling Language (OML) that allows platform independence for developing virtual environments.…”

The H-N2N framework: towards providing interperception in massive applications

“…Several communication architectures have been proposed considering the LS-CVE problem. One can mention NPSNET-4, DIVE, MR. TOOLKIT, BRICKNET, MASSIVE, and VELVET [7,11,16,20,25,26] amongst others. Comparison of several of such architectures has been performed based on aspects related to visualization [6], information, process and user distribution [6], and network communication [15].…”

Language-level support for exploratory programming of distributed virtual environments

“…MR implements a simple shared virtual memory model [28]. Raw memory locations can be marked as shared and local changes explicitly "flushed" to the other copies, which must then explicitly receive the changes.…”