Standards for Graph Algorithm Primitives

It is our view that the state of the art in constructing a large collection of graph algorithms in terms of linear algebraic operations is mature enough to support the emergence of a standard set of primitive building blocks. This paper is a position paper defining the problem and announcing our intention to launch an open effort to define this standard.Comment: 2 pages, IEEE HPEC 201

THALIA: Test harness for the assessment of legacy information integration approaches

We introduce a new, publicly available testbed and benchmark called THALIA (Test Harness for the Assessment of Legacy information Integration Approaches) to simplify the evaluation of existing integration technologies and to enable more thorough and more focused testing. THALIA provides researchers with a collection of downloadable data sources representing University course catalogs, a set of twelve benchmark queries, as well as a scoring function for ranking the performance of an integration system. Our benchmark focuses on syntactic and semantic heterogeneities since we believe they still pose the greatest technical challenges. A second important contribution of this paper is a systematic classification of the different types of syntactic and semantic heterogeneities, which directly lead to the twelve queries that make up the benchmark. A sample evaluation of two integration systems at the end of the paper is intended to show the usefulness of THALIA in identifying the problem areas that need the greatest attention from our research community if we want to improve the usefulness of today’s integration systems. 1

Abstract Contract-Based Load Management in Federated Distributed Systems ∗

This paper focuses on load management in looselycoupled federated distributed systems. We present a distributed mechanism for moving load between autonomous participants using bilateral contracts that are negotiated offline and that set bounded prices for moving load. We show that our mechanism has good incentive properties, efficiently redistributes excess load, and has a low overhead in practice. Our load management mechanism is especially wellsuited for distributed stream-processing applications, an emerging class of data-intensive applications that employ a “continuous query processing ” model. In this model, streams of data are processed and composed continuously as they arrive rather than after they are indexed and stored. We have implemented the mechanism in the Medusa distributed stream processing system, and we demonstrate its properties using simulations and experiments.

Database Research: Achievements and Opportunities Into the 21st Century

this paper reports on our findings

Availability-Consistency Trade-Offs in a Fault-Tolerant Stream Processing System

processing. In contrast to previous techniques that handlenode failures, our approach also tolerates network failuresand network partitions. The approach is based on a principledtrade-off between consistency and availability in theface of failure, that (1) ensures that all data on an inputstream is processed within a specified time threshold, but(2) reduces the impact of failures by limiting if possible thenumber of results produced based on partially available inputdata, and (3) corrects these results when failures heal.Our approach is well-suited for applications such as environmentmonitoring, where high availability and Âreal-timeÂresponse is preferable to perfect answers.Our approach uses replication and guarantees that all processingreplicas achieve state consistency, both in the absenceof failures and after a failure heals. We achieve consistencyin the former case by defining a data-serializing operatorthat ensures that the order of tuples to a downstreamoperator is the same at all the replicas. To achieve consistencyafter a failure heals, we develop approaches based oncheckpoint/redo and undo/redo techniques.We have implemented these schemes in a prototype distributedstream processing system, and present experimentalresults that show that the system meets the desiredavailability-consistency trade-offs