Period: October - December 1996
Title: Collaboration Bus: An Infrastructure for Supporting Interoperating Collaborative Systems
Contractor: University of North Carolina at Chapel Hill.
PI: Prasun Dewan
Contractor P/R No: N 66001-96-8507
AO_NUMBER: E357
We plan to take the following specific steps to meet this general goal: (a) Identify the services that a collaborative application requires. (b) Identify a reference model for each of these services. (c) Identify semantics translations and composition functions for each of these services. (d) Incorporate, into the bus, a default implementation of the service and the associated semantic translations and composition functions. (e) Develop mechanisms and policies for replicating and migrating parts of the bus. (f) Develop mechanisms for protecting the operations on the bus. (g) Carry out interoperability experiments involving each of these services using state-of-the-art existing software.
Anshu Sharma and Vassil Roussev, in the process of developing a distributed collaborative version of the spreadsheet, identified and solved a subtle problem with integrating the Java Remote Method Invocation and Observer/Observable packages. The problem has to do with the fact that RMI cannot be used directly for interacting with objects of existing Java protocols/classes, and the solution involved creating an extra proxy object at the remote site. They are currently documenting the problem and its solution.
Dewan wrote up a strawman design of the reference architecture. It extends the basic model-view view of an interactive components with several other components for supporting collaboration. Currently, it is a very high-level abstract design, and Sharma and Roussev have started a project to make it more concrete it by implementing a simple version of it in a distributed, collaborative spreadsheet.
John Smith and Qian Li designed and partly implemented generic Java objects and user-interfaces for persistent graph data structures. They based their design on the user-interface and data models of the ABC graph storage system developed at UNC. They plan to use these objects to encapsulate and interoperate existing ABC graphs, Web nodes, and Unix files/directories.
In the area of real-time services, Kevin Jeffay continued worked on the design of a quality-of-service manager for shared, distributed, virtual environments. In collaboration with the Intel Architecture Labs in Hillsboro, OR, graduate students Michele Clark and Peter Nee developed a prototype system in the Intel ProShare(TM) desktop videoconferencing system. The system monitors congestion in the network, feeds this information back to the sender who in turn attempts to adapt the outgoing media streams to ameliorate the effects of network congestion on the application's performance. Experiments using this system across the Internet were begun. The goal is to understand the limits on Rbest effortS real-time communications across the Internet for interactive, collaborative applications. This study will form the basis for the final design of a quality-of-service manager for distributed VEs. A second effort involving Kevin Jeffay and Mark Parris (an IBM Graduate Fellowship holder) is attempting to understand how transport-layer media applications can be applied in the network, in particular in network routers, to further reduce the effects of network congestion. Parris worked on a paper design of such a router. Ultimately he will implement the design by modifying the FreeBSD operating system.
FY96 Base 68,138
FY97 Base 394,868
FY98 Base 311,215
FY99 Base 207,476
TOTAL Base 981,697
Obligated to date.
138,130
Expenses and Encumberances this quarter.
46,933
Expenses and Encumberances to date.
15,181 + 46,933 = 62,114
Date current funding will be exhausted
22 JUL 1996 - 15 DEC 1996