Frank Manola

PROBE spatial data modeling and query processing in an image database application

The PROBE research project has produced results in the areas of data modeling, spatial/temporal query processing, recursive query processing, and database system architecture for nontraditional application areas, many of which involve spatial data and data with complex structure. An overview of PROBE is provided, focusing on the facilities for dealing with spatial and temporal data. It is shown how the PROBE database system and simple application-specific object classes combine to efficiently support PROBEs spatial data model. It is also shown how an image-database application can be supported using PROBEs data model and spatial query processor. The current status of the PROBE project and future plans are discussed. >

Traversal recursion: a practical approach to supporting recursive applications

Many capabilities that are needed for recursive applications in engineering and project management are not well supported by the usual formulations of recursion. We identify a class of recursions called “traversal recursions” (which model traversals of a directed graph) that have two important properties they can supply the necessary capabilities and efficient processing algorithms have been defined for them. First we present a taxonomy of traversal recursions based on properties of the recursion on graph structure and on unusual types of metadata. This taxonomy is exploited to identify solvable recursions and to select an execution algorithm. We show how graph traversal can sometimes outperform the more general iteration algorithm. Finally we show how a conventional query optimizer architecture can be extended to handle recursive queries and views.

DISTRIBUTED OBJECT MANAGEMENT

Future information processing environments will consist of a vast network of heterogeneous, autonomous, and distributed computing resources, including computers (from mainframe to personal), information-intensive applications, and data (files and databases). A key challenge in this environment is providing capabilities for combining this varied collection of resources into an integrated distributed system, allowing resources to be flexibly combined, and their activities coordinated, to address challenging new information processing requirements. In this paper, we describe the concept of distributed object management, and identify its role in the development of these open, interoperable systems. We identify the key aspects of system architectures supporting distributed object management, and describe specific elements of a distributed object management system being developed at GTE Laboratories.

Object orientation in heterogeneous distributed computing systems

The basic properties of object orientation and their application to heterogeneous, autonomous, and distributed system to increase interoperability ar examined. It is argued that object-oriented distributed computing is a natural step forward from client-server systems. To support this claim, the differing levels of object-oriented support already found in commercially available distributed systems-in particular, the distributed computing environment of the open software foundation and the Cronus system of Bolt Beranek, Newman (BBN)-are discussed. Emerging object-oriented systems and standards are described, focusing on the convergence toward a least-common-denominator approach to object-oriented distributed computing embodied by the object management groups common object request broker architecture.<<ETX>>

Customizing transaction models and mechanisms in a programmable environment supporting reliable workflow automation

A Transaction Specification and Management Environment (TSME) is a programmable system that supports implementation-independent specification of application-specific extended transaction models (ETMs) and configuration of transaction management mechanisms (TMMs) to enforce specified ETMs. The TSME can ensure correctness and reliability while allowing the functionality required by workflows and other advanced applications that require access to multiple heterogeneous, autonomous, and/or distributed (HAD) systems. To support ETM specification, the TSME provides a transaction specification language that describes dependencies between transactions. Unlike other ETM specification languages, TSMEs dependency descriptors use a common set of primitives, and are enforceable, i.e., can be evaluated at any time during transaction execution to determine whether operations issued violate ETM specifications. To determine whether an ETM can be enforced in a specific HAD system environment, the TSME supports specification of the transactional capabilities of HAD systems, and comparison of these with ETM specifications to determine mismatches. To enforce ETMs that are more restrictive than those supported by the union of the transactional capabilities of HAD systems, the TSME provides a collection of transactional services. These services are programmable and configurable, i.e., they accept instructions that change their behavior as required by an ETM and can be combined in specific ways to create a run-time TMM capable of enforcing the ETM. We discuss the TSME in the context of a distributed object management system. We give ETM specification examples and describe corresponding TMM configurations for a telecommunications application.

Specification and management of extended transactions in a programmable transaction environment

A Transaction Specification and Management Environment (TSME) is a transaction processing system toolkit that supports the definition and construction of application-specific extended transaction models (ETMs). The TSME provides a transaction specification language that allows a transaction model designer to create implementation-independent specifications of extended transactions. In addition, the TSME provides a programmable transaction management mechanism that assembles and configures a run-time environment to support specified ETMs. The authors discuss the TSME in the context of a distributed object management system (DOMS), and describe specifications of extended transactions and corresponding configurations of transaction management mechanisms.<<ETX>>

Report on the workshop on heterogenous database systems held at Northwestern University Evanston, Illinois, December 11-13, 1989 sponsored by NSF

Advances in networking and database technology during the past decade have changed dramatically the information processing requirements of organizations and individuals. An organization may have heterogenous database systems which differ in their capabilities and structure and which may be dispersed over a number of sites. In addition to these characteristics of heterogeneity and distribution, the ever larger number of databases available in the public and private domain makes it imperative to allow shared access to these databases in such a way that individual systems maintain their autonomy. Thus it becomes necessary to develop new techniques and provide new functionality to support the interoperability of autonomous database systems without requiring their global integration. Furthermore, the demands for interoperability extend beyond database systems to include office information systems, information retrieval systems and other software systems. Research into the interoperability of heterogenous database systems plays an important role in the development of high level open systems. This important fact has been recognized not only in the United States but also in Japan and in Europe, with Japan having allocated around

Generalizing Dispatching in a Distributed Object System

120M over five years for research and development in this area. The objective of this workshop was to explore current approaches to interoperability of autonomous information systems and to identify the most important research directions to be pursued in this area. This report summarizes our discussions and broadly classifies the issues into the following categories: 1

On Knowledge-Based System Architectures

Todays distributed computing environment presents a jungle of systems that use different object models, programming languages, and paradigms. Taking maximum advantage of these diverse resources requires that they be able to interoperate. We report on a series of experiments in a distributed object system that show how a flexible notion of dispatching can be used to integrate objects belonging to different models, systems, and paradigms.

An Overview of PDM: An Object-Oriented Data Model

This chapter investigates architectural issues of Knowledge-Base Management Systems (KBMSs) that might result from the integration of Knowledge-Base (KB) systems and Database Management Systems (DBMS) technology. A hypothetical KBMS architecture is presented that assumes the decomposition and current KB systems and DBMSs into components that may themselves be KB systems. The architecture is for a system of heterogeneous, distributed, cooperating KB components that actively participate in problem solving (e.g., Knowledge Management and KB application components cooperate, a DBMS query optimizer cooperates with other KB planning components.) The architecture is used to investigate the systems concept of a KBMS, its potential functionality, related systems issues, and types of integration.