Object-Orientation FAQ

Status:-
CLOSQL is a research prototype OODB designed primarily for prototyping
various schema evolution and view mechanisms based on class versioning.
The system is built using CommonLISP. It would really only be of interest
to other parties as a research tool.

Requirements:-
Common LISP including CLOS standard. The Graphical user interface requires
the Harlequin LispWorks Tool-kit. The system was built on a Sun4 and
has not been tested on any other platform.

Features:-
As a prototype, CLOSQL is not robust enough to sell. The system is single
user and does not properly support persistence - that is, the data has to
be loaded and saved explicitly. The query language is quite good
making good use of the functional nature of the environment.
Methods (LISP and query language only), class versioning and
multiple inheritance are all supported in the data model. Type checking
information is held in the database, but is NOT enforced at present. The
GUI is notable for its support for schema evolution, but otherwise rather
ordinary.

Availability:-
Probably freely available, but as the project was part funded by an
industrial partner, some consultation with them would be necessary before
the system could be released.

References:-
[1]  Monk, S. R. and I. Sommerville, "A Model for Versioning of Classes
in Object-Oriented Databases", Proceedings of BNCOD 10, Aberdeen.
pp.42-58. 1992.

[2]  Monk, S. "The CLOSQL Query Language". Technical report No. SE-91-15.
Computing Dept, Lancaster University, Lancaster, LA1 4YR, UK. 1991.

[3]  Monk, S., "A Model For Schema Evolution In Object-Oriented Database
Systems", PhD thesis, Dept of Computing, Lancaster University, Lancaster
LA1 4YR, UK. 1992.

On Schema evolution (from original survey):
CLOSQL implements a class versioning scheme (like ENCORE), but employs a
conversion adaptation strategy.  Instances are converted when there is a
version conflict, but unlike ORION and GemStone, CLOSQL can convert instances
to older versions of the class if necessary.

        Aberdeen, Scotland. July, 1992.

Contacts;
Simon Monk:      srm@computing.lancaster.ac.uk
Ian Sommerville: is@computing.lancaster.ac.uk