Enhanced active databases for federated information systems

Contents

1 Introduction

1.1 Motivation

1.2 Overview

2 Federated Information Systems

2.1 Why not one big database?

2.2 Basic Architecture

2.3 Distribution, Autonomy, and Heterogeneity

2.3.1 Distribution

2.3.2 Autonomy

2.3.3 Heterogeneity

2.4 Integration Challenges

2.4.1 Schema and Data Integration

2.4.2 Entity Resolution

2.4.3 Global Integrity

2.4.4 Global Transaction Management

2.5 Common Integration Architectures

2.5.1 Federated Database Systems

2.5.2 Mediator-based Information Systems

2.5.3 Peer Data Management Systems

3 Enhanced Active Database Systems

3.1 Definition

3.2 Enhanced Activity

3.3 External Program Calls

3.4 Discussion

3.5 Current EADBS

4 Active Event Notification

4.1 Monitoring Concepts

4.1.1 The Event Monitor

4.1.2 Change Capture Methods

4.1.3 Data Delivery Options

4.2 Related Work

4.2.1 Research Projects

4.2.2 Commercial Change Capture Products

4.3 Active Event Notification

4.3.1 Pull-based Asynchronous Notification

4.3.2 Push-based Synchronous Notification

4.3.3 Push-based Asynchronous Notification

4.3.4 Pull-based Synchronous Notification

5 Global Integrity Maintenance

5.1 Active Component Database Systems

5.2 Partial Integrity Constraints

5.2.1 Definition of Partial Integrity Constraints

5.2.2 Partial Integrity Constraints as ECA Rules

5.2.3 System Interaction

5.3 Checking Global Integrity Constraints

5.3.1 Attribute Constraints

5.3.2 Key Constraints

5.3.3 Referential Integrity Constraints

5.3.4 Aggregated Constraints

5.4 Discussion

5.5 Global Constraints with COMICS

5.5.1 System Overview

5.5.2 Checking Constraints with COMICS

5.6 Related Work

6 Tightly coupled Wrappers

6.1 Wrapper Architecture

6.2 Event Detection Subsystem

6.3 Application Fields

6.4 Related Work

7 The DÍGAME Architecture

7.1 Introduction

7.2 Basic Functionality

7.3 DÍGAME Architecture Components

7.4 Characteristics

7.5 Implementation Details

7.6 Related Work

8 Link Patterns

8.1 Motivation

8.2 The Data Link Modeling Language (DLML)

8.2.1 Introduction

8.2.2 DLML Components

8.2.3 Example

8.3 Link Patterns

8.3.1 Elements of a Link Pattern

8.3.2 Classification

8.3.3 Usage

8.4 Link Pattern Catalog

8.5 Example

8.6 Related Work

9 Conclusion and Future Work

9.1 Summary

9.2 Future Work

Research Objective and Scope

This work aims to enhance the interoperability and consistency of federated information systems by introducing "Enhanced Active Database Systems" (EADBS). The primary objective is to enable autonomous and heterogeneous database components to actively participate in global integrity maintenance and to propagate data changes in real-time without sacrificing local autonomy.

• Architectural concepts for EADBS to interact with external components.
• Implementation of "Active Event Notifications" for immediate, push-based data delivery.
• Strategies for global integrity maintenance using partial integrity constraints.
• Development of a tightly coupled wrapper architecture for heterogeneous data sources.
• Guidelines for modeling data flows in federated systems via the Link Pattern Catalog.

Excerpt from the Book

Summary of Chapters

Introduction: Provides the motivation for integrating autonomous databases and introduces the thesis's focus on Enhanced Active Database Systems (EADBS).

Federated Information Systems: Discusses the theoretical background, including distribution, autonomy, heterogeneity, and common integration challenges in federated systems.

Enhanced Active Database Systems: Defines EADBS and describes their capability to execute external programs to interact with their environment.

Active Event Notification: Presents a concept for immediate, real-time update notifications in federated systems using active capabilities.

Global Integrity Maintenance: Details how EADBS can actively maintain global integrity constraints through partial constraints and external interaction.

Tightly coupled Wrappers: Describes a universal wrapper architecture designed for real-time event delivery and interaction with EADBS.

The DÍGAME Architecture: Introduces the DÍGAME architecture for P2P-based information systems with push-based data replication.

Link Patterns: Proposes a catalog of Link Patterns and a modeling language (DLML) for recurring data flow problems in information grids.

Conclusion and Future Work: Summarizes the contributions and provides an outlook on potential future research directions.

Keywords

Federated Information Systems, Active Databases, Enhanced Active Database Systems, Global Integrity Maintenance, Event Notification, Real-time Data Delivery, Peer-to-Peer, Wrappers, Data Grid, Link Patterns, Data Integration, Consistency, Interoperability, Distributed Systems, Middleware

Frequently Asked Questions

What is the core focus of this thesis?

The thesis focuses on enhancing the functionality of modern active database systems to improve information sharing, consistency, and interoperability in federated and distributed information systems.

What are "Enhanced Active Database Systems" (EADBS)?

EADBS are a subclass of active databases that can execute external programs (written in standalone languages like Java) from within database triggers, allowing them to interact with software or hardware components beyond their own system borders.

What is the primary goal of the proposed Active Event Notification?

The goal is to enable truly immediate, real-time notification of external components about local data modifications, avoiding the performance overhead of traditional periodic polling or snapshot mechanisms.

How is global integrity maintained in these federated systems?

Integrity is maintained by decomposing global constraints into "partial integrity constraints" that are enforced locally by each component database, which can communicate with other sources during transaction execution to check remote constraints.

What role do the "Tightly coupled Wrappers" play?

These wrappers encapsulate heterogeneous data sources and provide a uniform interface for the federation, while specifically incorporating event detection and notification capabilities to support real-time data integration.

What are the key terms associated with this research?

Key terms include Federated Information Systems, Active Databases, Event Notification, Global Integrity Maintenance, Peer-to-Peer, and the Link Pattern Catalog for modeling data flows.

What is the purpose of the DÍGAME architecture?

DÍGAME is an architecture designed for P2P-based information grids that balances local autonomy with high data availability through a push-based replication strategy.

How does the Link Pattern Catalog assist developers?

It provides a standardized set of modeling guidelines and a vocabulary for describing, analyzing, and optimizing complex data flows within large-scale information grids.