This paper introduces a directed hypergraph model that supports (1) workflow composition and reconfiguration while accessing and executing programs, data, and computing resources across the Internet, (2) synchronous and asynchronous peer-to-peer interaction between members of any team during workflow composition and execution, (3) synchronous and asynchronous peer-to-workflow interaction between any team member and any object in the workflow. Given a library of program and data nodes, editing the workflow and its execution is as intuitive as the hierarchical schematic design capture and simulation. Examples of multisite multi-user applications demonstrate that the proposed workflow implementation provides a user-friendly paradigm for distributed and collaborative team design.

In the Internet community there is a strong demand for platform-independent collaboration software. Java is developed with the major design goals of being a platformindependent, and Internet-oriented programming language. In this paper we show how a group of Internet users can share single-user Java applications for synchronous collaboration. Our approach is based on replicated tool architecture in which each participant runs a copy of the application and the activity of each user is multicast to all the participants in the conference. We have developed a system called Java Collaborative Environment (JCE), on which the Java's Abstract WindowToolkit (AWT) is extended such that mouse and keyboard events are intercepted and distributed among all copies of the shared Java application. In addition we provide an infrastructure and a simple interface for session management and floor control.

Abstract- The Internet-based desktop environment as defined in this paper consists of a cross-platform browser, a number of server icons (host nodes), a number of application icons (program nodes) and a number of data iwns’(file nodes). In contrast to typical desktops of today, where data icons may be dragged and dropped onto application icons for execution, this environment allows (I) user-defined and reconfigurable execution sequences by creating dependency edges between program nodes (application icons) and file nodes (data icons); (2) data-dependent execution sequences by dynamic scheduling of path as well as loop executions; (3) host-transparency as to the location of applications and data (60th can reside on any host with a unique IP address). We argue that the Internet-based workflow paradigm is suitable for creation of dynamically reco;lfigurable desktop en-vironments. demonstrates The summary of 450 Internet-based expen’ments (1) the value of making the desktop recordable, and (2) the feasibility of rendering it collaborative.

Shared window systems allow collaboration-transparent, single-user applications to be displayed and interacted with on multiple users' workstations, enabling the members of a cooperative ensemble to simultaneously share and revise information. This paper presents a system capable of sharing applications running under the X Window System. In contrast to previously implemented systems, our shared window system addresses issues that are crucial for general-purpose use. Our shared window system is policy-free, i.e. there are no preferred policies for handling issues such as admission and floor control. Instead, it offers a set of essential mechanisms on top of which various policies and user paradigms may be realized. Further, the system distributes the sharing functionality among all sites involved in a cooperative activity. Measurements have shown a positive impact of this on the overall performance of the system and thus justified the viability of the design decisions taken. I.

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We describe the Scene-Graph-As-Bus technique (SGAB), the first step in a staircase of solutions for sharing software components for virtual environments. The goals of SGAB are to allow, with minimal effort, independentlydesigned applications to share component functionality; and for multiple users to share applications designed for single users.This paper reports on the SGAB design for transparently conjoining different applications by unifying the state information contained in their scene graphs. SGAB monitors and maps changes in the local scene graph of one application to a neutral scene graph representation (NSG), distributes the NSG changes over the network to remote peer applications, and then maps the NSG changes to the local scene graph of the remote application. The fundamental contribution of SGAB is that both the local and remote applications can be completely unaware of each other; that is, both applications can interoperate without code or binary modification despi...

Reliable multicast protocols are becoming an essential element in distributed applications such as interactive distance learning applications. However, the existing implementations of reliable multicast protocols are not sufficient to satisfy the group communications requirements of some distributed applications. Our experience of using number of multicast protocols in IRI distance learning applications shows the necessity of providing an application-layer Reliable Multicast Server (RMS) to extend the primitive group communication services provided by such multicast protocols. Examples of such services include handling heterogeneous environments (such as LAN vs. WAN networks and different reliable multicast protocols), automatic fault recovery and simple application interface. In this paper, we motivate and describe the design and the implementation of RMS architecture which has been used in IRI learning sessions for two semesters. We also show how RMS improves the reliability, perform...

This paper discusses the software architecture, interprocess communication and the reference implementation of IRI, an Interactive Remote Instruction system for distance learning. IRI is an Internet-based system which integrates continuous multimedia, shared applications and a variety of multi-user collaborative utilities. Internet multicasting is used by IRI for group management and data sharing; UDP-multicasting is used for audio and video streams while reliable multicasting protocol (RMP) is used by XTV, the data sharing engine of IRI. The system is both scalable and expandable. It is scalable through the use of multicasting for interprocess communication. It is expandable due to its partitioning into a set of autonomous but cooperating components. The interaction among components is specified by a set of messages and the functions needed to send and receive these messages. 1 Introduction Over the past two years, faculty and students in the Department of Computer Science at Old Dom...

Tasks in a distributed benchmarking or design environment are complex and variable. A single paradigm is not suitable for all tasks and teams, and a paradigm that suits a task and a team for some time may not be suitable for all of the time. The notion of a collaborative workflow as introduced in this paper is founded on a reconfigurable and composable graph-based representation of objects such as programs, files, decisions, scripts, host definitions, team definitions, and recorded sessions which are shared across the Internet. Workflows can be executed and controlled in real-time by several distributed participants or can be scheduled for batch execution and interaction. The collaborative environment we created is being tested in the context of design of experiments, exploring a way for an open, peer-reviewed series of benchmarking experiments using the Internet. In a parallel effort, we are exploring availability, for the first time, of large classes of equivalent class circuit mutan...

IRI is an Interactive Remote Instruction multimedia system for distance learning. It integrates audio, video, shared applications and multi-user collaborative utilities. In this paper we concentrate on the process architecture and dynamic multicast group handling as they pertain to multimedia and show how they support robustness and short response time to user actions. IRI uses raw IP multicasting for audio and video streams and reliable multicasting for data sharing. The system is scalable (uses multicast for inter-process communication) and expandable (it is partitioned into a set of autonomous but cooperating components). In addition, we present a series of experiments that show how the machine workload influences the audio and video subsystem. Finally, we discuss the techniques used to record and playback an IRI session. KEY WORDS: Integration of Multimedia Information, Interactive Multimedia, Applications of Multimedia in Distance Learning, Multicasting, Distributed Systems. 1 In...