Implementation of a Rule-Based Framework for Managing Updates in an Object-Oriented VPF Database,
Abstract
This paper presents an approach for supporting reactive capability in an object oriented GIS database, through the use of an event interface comprising an event generator and rule objects. This interface supports specification of events spanning sets of geographic feature objects, and detection of primitive and complex events Rules can be specified to apply either at a class level (i.e., to all instances of a given geographic- feature class) or at an instance level. In addition we allow evaluation of both pre- and post-conditions on changes to a feature. This approach is relevant in three distinct situations: (1) immediate mode, to execute rules immediately before or after some state change; (2) deferred mode, to execute rules at the end of several changes; and (3) detached mode, to perform rule-based actions separately from the state changes. GIS presents a rich set of problems for which this approach can be useful. This paper outlines the key elements of the rule-based approach employed in an object-oriented framework used for viewing and editing Vector Product Format (VPF) source data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 16, 1995
- Accession Number
- ADA308276
Entities
People
- David K. Arctur
- Emaan Anwar
- Maria Cobb
- Miyi Chung
- Sharma Chakravarthy
Organizations
- United States Naval Research Laboratory