| EPSRC Reference: |
GR/J44162/01 |
| Title: |
CONSTRAINT SATISFACTION IN OBJECT-ORIENTED DATABASES |
| Principal Investigator: |
Gray, Professor P |
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| Department: |
Computing Science |
| Organisation: |
University of Aberdeen |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
01 January 1994 |
Ends: |
30 April 1997 |
Value (£): |
101,848
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| EPSRC Research Topic Classifications: |
| Information & Knowledge Mgmt |
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Summary on Grant Application Form |
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A program of work centred on the newly developed technology of constraint programming. We wish to investigate:(a) The extension of our object-oriented data model P/FDM to include constraints and metaclass information, including extensions to the Daplex syntax.(b) The generation of constraint logic programming code to solve declarative problem specifications combined with stored constraints inherited from various classes in the database.(c) The use of constraints to repair or restore a consistent state of the database, based on constraint equations and constraint logic programming.Progress:Our main focus so far has been to stabilise the implementation of the P/FDM database system, and to make the alterations necessary for the addition of the new language features and the transaction repair subsystem. This has included: the redesign of the Daplex compiler to allow individual modules, such as the optimiser and code generator, to be used in new ways. the underlying storage schemas have been altered and the update primitives rewritten to give better performance under transactions and, as a by-product, better general performance. the syntax of our constraint language has been altered in the light of a study of the constraints present in a complex domain (protein structure), and the constraint compiler has been extended to cover all constraints expressible in the new language.While implementing these changes we have also completed the port of P/FDM to SICStus (which was begun in another project at Aberdeen), with a view to producing an easily-distributable final product. The implementation of the Daplex-to-Chip compiler is under way. The basic framework is almost complete, and we are beginning to consider compilation strategies for the kinds of constraints found in our application domain. Future Plans: The next major steps in the project are to complete the Daplex-to-Chip compiler (and to validate it by experimenting with problems in the protein structure database), and to implement our proposed algorithm for checking constraints on transaction-commit. The algorithm uses partially-instantiated templates in order to reduce the amount of data retrieval required to check a large set of constraints, and produces output in a form suitable for use in transaction repair. For the remainder of the project, we will explore the combined use of the Daplex-to-Chip compiler and the constraint handling techniques provided by Chip in generating update strategies which will restore consistency to long-duration design transactions, in the context of the protein database.
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Key Findings |
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Potential use in non-academic contexts |
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.abdn.ac.uk |