Dynamic UNITY

Dynamic distributed systems, where a changing set of communicating processes must interoperate to accomplish particular computational tasks, are becoming extremely important. Designing and implementing these systems, and verifying the correctness of the designs and implementations, are difficult tasks. The goal of this thesis is to make these tasks easier. This thesis presents a specification language for dynamic distributed systems, based on Chandy and Misra's UNITY language. It extends the UNITY language to enable process creation, process deletion, and dynamic communication patterns. The thesis defines an execution model for systems specified in this language, which leads to a proof logic similar to that of UNITY. While extending UNITY logic to correctly handle systems with dynamic behavior, this logic retains the familiar UNITY operators and most of the proof rules associated with them. The thesis presents specifications for three example dynamic distributed systems to demonstrate the use of the specification language, and full correctness proofs for two of these systems and a partial correctness proof for the third to demonstrate the use of the proof logic. The thesis details a method for determining whether a system in the specification language can be transformed into an implementation in a standard programming language, as well as a method for performing this transformation on those specifications that can. This guarantees a correct implementation for any specification that can be so transformed

Snapshot Processing in Streaming Environments

Computational issues related to streaming data, and in particular the monitoring and rapid correlation of multiple sources of streaming data, are becoming increasingly important in contexts ranging from business processes to crisis detection. For example, a government system to detect bioterror attacks must correlate multiple streams of possibly low-confidence data from sensors and local and national public health information networks with cues from indicators such as news and government sources indicating geographical locations, tactics and timing of possible attacks. The results of this correlation trigger appropriate responses, such as flagging information for more in-depth analysis or sending alerts to public health officials. Monitoring and correlation applications of this type are ideal for deployment on distributed computing grids, because they have high transaction throughput, require low latency, and can be partitioned into sets of small communicating computations with regular communication patterns. An important consideration in these applications is the need to ensure that, at any given time, computations are carried out on an accurate - or at least close to accurate - picture of the environment being monitored. One way of doing this, which we call snapshot processing, is to treat collections of events that occur at approximately the same time as representing a global snapshot - a valid state - of the environment. Computation on the resulting series of snapshots is much like computation on a real-time video of the entire environment. We briefly describe our model for these stream processing computations and introduce the concept of snapshot processin

A parallel algorithm for correlating event streams

This paper describes a parallel algorithm for correlating or “fusing” streams of data from sensors and other sources of information. The algorithm is useful for applications where composite conditions over multiple data streams must be detected rapidly, such as intrusion detection or crisis management. The implementation of this algorithm on a multithreaded system and the performance of this implementation are also briefly described

Enterprise Computing Systems as Information Factories

The analysis, and eventual approval or rejection, of new enterprise information technology (IT) initiatives often proceeds on the basis of informal estimates of return on investment. Investment in new IT initiatives includes the costs of hardware, software licenses, application development tailored to the enterprise, and maintenance. Returns are typically estimated informally in terms of cost savings or revenue increases. This paper makes the case for evaluating certain IT investments in the same way as investments in factories and other resources have been evaluated for decades. Just as industrial factories create value by transforming raw materials into finished products, some IT investments, which we call “information factories”, create value by transforming raw information (events) into structured data (and possibly actions based on that data). The return on investment is estimated by the difference between the economic value of the structured data and concomitant actions (the “finished product”) and that of the data available within the enterprise, from its partners and customers, and from the Internet (the “raw materials”). This paper introduces the concept of the information factory, and explores design considerations for maximizing the economic efficiency of information factories

A Preliminary Investigation into Dynamic Distributed Workflow

In this thesis, we describe the concept of dynamic distributed workflow. We briefly discuss three possible approaches to the construction of a system to support dynamic distributed workflow, and identify theoretical questions which arise when considering the operation of such a system. We also present UberNet, a Java-based system which implements inter-object communication as a limited form of dynamic distributed workflow. This system, which provides extremely powerful communication capabilities to distributed Java objects, serves both as a proof of concept for dynamic distributed workflow and as a starting point for the future implementation of more complex dynamic distributed workflow systems

Constructing Client-Server Multi-Player Asynchronous Networked Games Using a Single-Computer Model

We examine the process of creating asynchronous networked games by applying systematic transformations to their single-computer analogues, identify the need for such transformations, and propose a simple system of rules for them. In developing these rules, our primary concerns are comparing the flow of events in single-processor and networked games and examining the restrictions and limitations resulting from speed considerations. Although this paper only discusses games, the transformation rides may apply to any networked application with asynchronous data input and exchange

Assessment of abattoir based monitoring of PRRSV using oral fluids

Various porcine reproductive and respiratory syndrome virus (PRRSV) regional elimination projects have been implemented in the U.S., but none have yet succeeded. In part, this reflects the need for efficient methods to monitor over time the progress of PRRSV status of participating herds. This study assessed the feasibility of monitoring PRRSV using oral fluids collected at the abattoir. A total of 36 pig lots were included in the study. On-farm oral fluid (n = 10) and serum (n = 10) collected within two days of shipment to the abattoir were used to establish the reference PRRSV status of the population. Oral fluids (n = 3 per lot) were successfully collected from 32 lots (89%) at the lairage. Three veterinary diagnostic laboratories (VDLs) tested the sera (VDL1 and VDL3: n = 316, VDL2: n = 315) and oral fluids (VDL1 and VDL3: n = 319, VDL2: n = 320) for PRRSV antibodies (ELISA) and RNA (rRT-PCR). Environmental samples (n = 64, 32 before and 32 after pigs were placed in lairage) were tested for PRRSV RNA at one VDL. All oral fluids (farm and abattoir) tested positive for PRRSV antibody at all VDLs. PRRSV positivity frequency on serum ranged from 92.4% to 94.6% among VDLs, with an overall agreement of 97.6%. RNA was detected on 1.3% to 1.9%, 8.1% to 17.7%, and 8.3% to 17.7% of sera, on-farm and abattoir oral fluids, respectively. Between-VDLs rRT-PCR agreement on sera and oral fluids (farm and abattoir) ranged from 97.8% to 99.0%, and 79.0% to 81.2%, respectively. Between-locations agreement of oral fluids varied from 31.3% to 50% depending on the VDL. This study reported the application of swine oral fluids collected at the abattoir for monitoring PRRSV, and describes the between-VDL agreement for PRRS testing of serum and oral fluid field samples

Changing Trends in the Undergraduate Fraternity/Sorority Experience: An Evaluative and Analytical Literature Review

Fraternal organizations in American institutions of higher education have a significant influence on student life and campus culture. Historically, research has shown that fraternities and sororities provide environments that support negative and often illegal activities that can be detrimental to individuals and communities at large. However, recent research has identified new trends that suggest this may be changing. This article identifies these trends and implications