Fusion Channels: A Multi-sensor Data Fusion Architecture

Due to the falling price and availability of sensors, information capture and processing at a realtime or soft realtime rate is emerging as a dominating application space. This class includes interactive multimedia, robotics, security and surveillance applications and many more. A common denominator of these applications is fusion of data gathered by various sensors and data aggregators. In this paper we propose a Data Fusion architecture, specifically geared toward such multi-sensor data fusion applications and report on the prototype we have built. Our infrastructure provides a programming abstraction that offers programming ease, at the same time provides built-in optimizations that are quite complicated to implement from scratch. We show the ease of programming through two sample applications and also demonstrate through various experiments that our system has low overhead and offers better performance compared to otherwise naively written fusion routines. We also demonstrate improved scalability

Causal Memory: Definitions, Implementation, and Programming

The abstraction of a shared memory is of growing importance in distributed computing systems. Traditional memory consistency ensures that all processes agree on a common order of all operations on memory. Unfortunately, providing these guarantees entails access latencies that prevent scaling to large systems. This paper weakens such guarantees by defining causal memory, an abstraction that ensures that processes in a system agree on the relative ordering of operations that are causally related. Because causal memory is weakly consistent, it admits more executions, and hence more concurrency, than either atomic or sequentially consistent memories. This paper provides a formal definition of causal memory and gives an implementation for message-passing systems. In addition, it describes a practical class of programs that, if developed for a strongly consistent memory, run correctly with causal memory

State Management in .NET Web Services

In the paper, we identify a problem for certain applications wishing to use the web service paradigm to enhance interoperability: rapid, robust state maintenance. We classify two kinds of state: application state and session state. While many features are available to support session data, special mechanisms for application state maintenance are less well developed. Application state maintenance is integral to providing reliable, fault-tolerant web services. We discuss three different models to solve the problem and compare the advantages and disadvantages of each. Experimental results show that the choice of which model to use depends on application requirements. Many important emerging applications will involve the communication of potentially large time-sequenced data streams among heterogeneous clients with varying QoS requirements. D-Stampede.NET is an implementation of a system designed to support the development of such applications. We describe our web service entation along with our state server solution to the application state management problem. A simple demo application is described and measured to validate performance

State Management in .NET . . .

In the paper, we identify a problem for certain applications wishing to use the web service paradigm to enhance interoperability: rapid, robust state maintenance. We classify two kinds of state: application state and session state. While many features are available to support session data, special mechanisms for application state maintenance are less well developed. Application state maintenance is integral to providing reliable, fault-tolerant web services. We discuss three different models to solve the problem and compare the advantages and disadvantages of each. Experimental results show that the choice of which model to use depends on application requirements. Many important emerging applications will involve the communication of potentially large time-sequenced data streams among heterogeneous clients with varying QoS requirements. D-Stampede.NET is an implementation of a system designed to support the development of such applications. We describe our web service implementation along with our state server solution to the application state management problem. A simple demo application is described and measured to validate performance

TV Watcher: Distributed Media Analysis and Correlation

The explosion of available content in broadcast media has created a desperate need for applications and prerequisite system architectures to support automatic capture, filtration, categorization, correlation, and higher level inferencing of streaming data from distributed sources. We present TV Watcher, an archetypical example of such an application. TV Watcher performs user-controlled correlation of live television feeds and allows the user to automatically navigate through the available channels based on content of interest. We introduce the Symphony architecture for distributed real-time media analysis and delivery to meet the system requirements for applications with such needs. TV Watcher is built on top of the Symphony architecture, and currently uses closed-captioning information to correlate television programming. We present the results of a user study that shows the correlation engine is consistently able to pick significantly useful and relevant content