We introduce River, a data-flow programming environment and I/O substrate for clusters of computers. River is designed to provide maximum performance in the common case --- even in the face of nonuniformities in hardware, software, and workload. River is based on two simple design features: a high-performance distributed queue, and a storage redundancy mechanism called graduated declustering. We have implemented a number of data-intensive applications on River, which validate our design with near-ideal performance in a variety of non-uniform performance scenarios.

) M. Livny, R. Ramakrishnan, K. Beyer, G. Chen, D. Donjerkovic, S. Lawande, J. Myllymaki and K. Wenger Department of Computer Sciences, University of Wisconsin--Madison 1210 W. Dayton St., Madison, Wisconsin 53706 Tel: (608)262-6611, Fax: (608)262-9777 fmiron,raghu,beyer,guangshu,donjerko,ssl,jussi,wengerg@cs.wisc.edu Abstract DEVise is a data exploration system that allows users to easily develop, browse, and share visual presentations of large tabular datasets (possibly containing or referencing multimedia objects) from several sources. The DEVise framework, implemented in a tool that has been already successfully applied to a variety of real applications by a number of user groups, makes several contributions. In particular, it combines support for extended relational queries with powerful data visualization features. Datasets much larger than available main memory can be handled---DEVise is currently being used to visualize datasets well in excess of 100MB--- and data can be in...

Abstract. This paper describes the objectives of the SEQUOIA 2000 project and the software development that is being done to achieve these objectives. In addition, several lessons relevant to Geographic Information Systems (GIS) that have have been learned from the project are explained. I.

Performance Availability for Networks of Workstations by Remzi H. Arpaci-Dusseau Software systems for large-scale distributed and parallel machines are difficult to build. When run in dynamic, production environments, not only must such systems perform correctly, but they must also operate with high performance. Much of the previous work in distributed computing has addressed the design of large-scale systems that function correctly, in spite of correctness faults of individual components [18, 49, 82, 86]. However, there has been little development of techniques to tolerate performance faults -- unexpected performance fluctuations from the components that comprise the system. Due to this shortcoming, many systems are overly sensitive to performance variations, in that global performance is high if and only if all system components perform exactly as expected. In this dissertation, we address this deficiency by formalizing the concept of performance availability. Our hypothesis is ...

Sequoia 2000 schema development is based on emerging geospatial standards to accelerate development and facilitate data exchange. This paper focuses on the metadata schema for digital satellite images. We examine how satellite metadata are defined, used, and maintained. We discuss the geospatial standards we are using, and describe a SQL prototype that is based on the Spatial Archive and Interchange Format (SAIF) standard and implemented in the Illustra object-relational database. 1 Introduction The Sequoia 2000 project is developing a computing environment to support global change research, involving large volumes of complex data in many formats [1,2]. 1 The design goals for the database schema that manages these data include: ffl Develop a database schema library composed of user-defined types and SQL templates that support earth science data. A researcher uses these building blocks to create a database schema for a specific application. ffl Include enough metadata so files can b...

In this paper we present a new architecture for visualization systems that is based on Data Base Management System (DBMS) technology. By building on the mechanisms present in a next-generation DBMS, rather than merely on the capabilities of a standard file manager, we show that a simpler and more powerful visualization system can be constructed. We retain the popular "boxes and arrows" programming notation for constructing visualization programs, but add a "flight simulator" model of movement to navigate the output of such programs. In addition, we provide a means to specify a hierarchy of abstracts of data of different types and resolutions, so that a "zoom" capability can be supported. The underlying DBMS support for this system, Tioga, is briefly described, as well as the current state of the implementation.

This paper presents VIQING, an environment for expressing queries via direct manipulation of data visualizations. VIQING provides a simple graphical interface for connecting visualizations, and has the expressive power of the basic relational operators select, project and join. VIQING has been implemented in the Tioga DataSplash visualization system to provide a seamless integration of querying and browsing. The resulting system is unique in providing a unified visual interface for developing database applications, encompassing both querying and data visualization. Key Words: database visualization, graphical query languages, direct-manipulation interfaces 1. Introduction Database systems are hard to use. Untrained users often find query interfaces frustrating and even trained database users frequently have difficulty analyzing the results of queries. Despite over 25 years of research in this area, these problems persist today. The goal of the Tioga project [14] has been to address th...

This paper describes the Sequoia 2000 software architecture and its current implementations, including layers for Footprint, the file system, the DBMS, applications, and the network. Early prototype applications of this software include a Global Change data schema, GCM integration, remote sensing, a data system for climate studies, and operational uses by the DWR. Longer-range efforts include transfer protocols for moving elements of the database, controllers for secondary and tertiary storage, distributed file system, and a distributed DBMS. The implementation plan ensures that the current architecture is stabilized and robust by the end of 1993. Contents 1 Introduction 1 2 The Sequoia 2000 Architecture 2 2.1 Objectives : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 2 2.1.1 High Performance I/O on Terabyte Data Sets : : : : : : : 2 2.1.2 All Data in a DBMS : : : : : : : : : : : : : : : : : : : : 3 2.1.3 Better Visualization Tools : : : : : : : : : : : : : : : : : 3 2.1....

Among the proposed innovations in the Clinton Administration's plans to develop a National Information Infrastructure is the creation of, and support for, digital or electronic libraries to store and provide access to the vast amounts of information expected to made available over the \information superhighway". Although the exact nature and future architecture of such libraries is still a matter for experimentation (and debate), there are several pioneering e orts underway to establish electronic libraries and to provide access to them. This paper describes one such e ort underway at the University of California at Berkeley. In collaboration with four other universities we are developing interoperable electronic library servers containing the Computer Science technical reports for each participant and making them available over the internet using standard protocols.

Scientific visualization applications are very dataintensive, with high demands for I/O and data management. Developers of many visualization tools hesitate to use traditional DBMSs, due to the lack of support for these DBMSs on parallel platforms and the risk of reducing the portability of their tools and the user data. In this paper, we propose the GODIVA framework, which provides simple databaselike interfaces to help visualization tool developers manage their in-memory data, and I/O optimizations such as prefetching and caching to improve input performance at run time. We implemented the GODIVA interfaces in a stand-alone, portable user library, which can be used by all types of visualization codes: interactive and batch-mode, sequential and parallel. Performance results from running a visualization tool using the GODIVA library on multiple platforms show that the GODIVA framework is easy to use, alleviates developers ’ data management burden, and can bring substantial I/O performance improvement. 1