Rule contexts in active databases

A mechanism for dynamic rule grouping
  • Martin Sköld
  • Esa Falkenroth
  • Tore Risch
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 985)

Abstract

Engineering applications that use Active DBMSs (ADBMSs) often need to group activities into modes that are shifted during the execution of different tasks. This paper presents a mechanism for grouping rules into contexts that can be activated and deactivated dynamically. The ADBMS monitors only those events that affect rules of activated contexts.

By dynamic rule grouping the set of monitored rules can be changed during the transactions. In a static rule grouping the rules are associated with specific objects during the schema definition.

A rule is always activated into a previously defined context. The same rule can be activated with different parameters and into several different contexts. Rules in a context are not enabled for triggering until the context is activated. However, rules can be directly activated into a previously activated context. When rule contexts are deactivated all the rules in that context are disabled from triggering.

The user defined contexts can be checked at any time in a transaction. Rule contexts can be used as a representation of coupling modes, where the ADBMS has built-in contexts for immediate, deferred, and detached rule processing. These built-in coupling modes are always active and are automatically checked by the ADBMS.

Contexts and rules are first-class objects in the ADBMS. Database procedures can be defined that dynamically activate and deactivate contexts and rules to support dynamically changing behaviours of complex applications.

The context mechanism has been implemented in the AMOS ADBMS. The paper concludes with an example of a manufacturing control application that highlights the need for rule contexts.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    Buchanan B. G., Shortliffe E. H.: Rule-based Expert Systems, The Mycin Experiments of the Stanford Heuristic Programming Project, Addison-Wesley, 1984Google Scholar
  2. [2]
    Davis R., Meta-rules: Reasoning about Control, AI, vol. 15, 1980, pp. 179–222Google Scholar
  3. [3]
    Dayal U., Buchman A.P., McCarthy D.R.: Rules are objects too: A Knowledge Model for an Active, Object-Oriented Database System, Proc. 2nd Intl. Workshop on Object-Oriented Database Systems, Lecture Notes in Computer Science 334, Springer 1988Google Scholar
  4. [4]
    Dayal U., McCarthy D.: The Architecture of an Active Database Management System, ACM SIGMOD conf., 1989, pp. 215–224Google Scholar
  5. [5]
    Fahl G., Risch T., Sköld M.: AMOS — An Architecture for Active Mediators, Intl. Workshop on Next Generation Information Technologies and Systems (NGITS '93) Haifa, Israel, June 1993, pp. 47–53Google Scholar
  6. [6]
    Fishman D. et. al: Overview of the Iris DBMS, Object-Oriented Concepts, Databases, and Applications, ACM press, Addison-Wesley Publ. Comp., 1989Google Scholar
  7. [7]
    Georgakopoulos D., Hornick M., Sheth A.: An Overview of Workflow Management: From Process Modelling to Workflow Automation Infrastructure, Distributed and Parallel Databases, 3, 2, April 1995, pp. 119–153Google Scholar
  8. [8]
    Hedberg S., Steizner M.: Knowledge Engineering Environment (KEE) System: Summary of Release 3.1, Intellicorp Inc. July 1987Google Scholar
  9. [9]
    Loborg P., Holmbom P., Sköld M., Törne A.: A Model for the Execution of Task-Level Specifications for Intelligent and Flexible Manufacturing Systems, Integrated Computer-Aided Engineering 1(3) pp. 185–194, John Wiley & Sons, Inc., 1994Google Scholar
  10. [10]
    Loborg P., Risch T., Sköld M., Törne A. Active Object Oriented Databases in Control Applications, 19th Euromicro Conference of Microprocessing and Microprogramming, vol. 38, 1–5, pp. 255–264, Barcelona, Spain 1993Google Scholar
  11. [11]
    Lyngbaek P., OSQL: A Language for Object Databases, tech. rep. HPL-DTD-91-4, Hewlett-Packard Company, Jan. 1991Google Scholar
  12. [12]
    Risch T.: Monitoring Database Objects, Proc. VLDB conf. Amsterdam 1989Google Scholar
  13. [13]
    Risch T., Sköld M.: Active Rules based on Object Oriented Queries, IEEE Data Engineering bulletin, Vol. 15, No. 1–4, Dec. 1992, pp. 27–30Google Scholar
  14. [14]
    Shipman D. W.: The Functional Data Model and the Data Language DAPLEX, ACM Transactions on Database Systems, 6(1), March 1981Google Scholar
  15. [15]
    Stonebraker M., Hearst M., Potamianos S.: A Commentary on the POSTGRES Rules System, SIGMOD RECORD, vol. 18, no. 13, Sept. 1989Google Scholar
  16. [16]
    Tombros D., Geppert A., Dittrich K. R.: SEAMAN: Implementing Process-Centered Software Development Environments on Top of an Active Database Management System, Technical Report 95.03, Comp. Science Dept., University of Zürich, Jan. 1995Google Scholar
  17. [17]
    Walters J.R, Nielsen N.R., Crafting Knowledge-based Systems — Expert Systems Made Easy/Realistic, John Wiley & Sons, 1988, pp. 253–284Google Scholar
  18. [18]
    Widom J.: The Starburst Rule System: Language Design, Implementation, and Applications, IEEE Data Engineering, vol. 15, no. 1–4, Dec. 1992Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • Martin Sköld
    • 1
  • Esa Falkenroth
    • 1
  • Tore Risch
    • 1
  1. 1.Department of Computer and Information ScienceLinköping UniversityLinköpingSweden

Personalised recommendations