TESS (Type Evolution Software System)
University of Massachusetts Arcadia Project
- Brief description:
TESS supports the evolution of persistent types by
semi-automatically generating a transformer that can translate
between two versions of a set of types. More specifically,
the input to TESS is two source files representing two
versions of a set of type definitions. TESS compares these
files and produces a transformer describing how to translate
instances of the old versions of the types into the new
versions of the types. Ultimately, the user will be able to
edit these descriptions if they are incorrect, but this is not
yet implemented. Also, a runtime environment to interpret
these descriptions and actually update the instances (either
permanently via converting the instances or virtually via
screening the instances) is planned, but does not yet exist.
- Evaluation against applicable general dimensions:
- Availability: commercial/licensed/public domain
Not currently available to the public.
- Degree of support/maturity/testing/usage:
In the worst case, the type comparison algorithm is
NP-complete. However, there are several features of the
system that make type comparison feasible. First, there are a
several heuristics to reduce the number of types that must
be compared. For example, types with the same names are
compared first. Given the nature of type changes in evolving
systems, this will typically offer good results and make it
unnecessary to compare these types to other types. Other
heuristics are also used to limit the number of comparisons.
Furthermore, the user has the ability to limit the kinds of
comparisons that are done to prevent an exhaustive search
comparison of the types, and also can focus the system on the
comparison of a pair of old and new types rather than entire
sets of types if necessary.
- Computing platforms:
SunAda 1.1 for Sun/SPARC
SUIT 2.3 (The Simple User Interface Toolkit from the
University of Virginia)
- Language compatibilities:
TESS is currently able to accept input written either in
- Kernel: 23381 SLOC
- Pleiades front-end: 529 SLOC
- User interface (C code): 1808 SLOC
- Total for Pleiades version: 25718 SLOC
- Openness/integrability/source availability:
The license includes source. Integration is restricted to
The kernel type comparison algorithms use a language
independent type model. A new version of Tess can be created
to compare types in a different language by creating a new
front-end for that language and a back-end capable of reading
and writing persistent objects of that language.
- Pedigree: ARPA developed?
- Contact person(s)
Dr. Lori A. Clarke (email@example.com)
Department of Computer Science
University of Massachusetts
Amherst, MA 01003
(413) 545-1249 - fax
- Pointers to literature, demos, etc.:
- David Garlan, Charles W. Krueger, Barbara Staudt Lerner.
TransformGen: Automating the Maintenance of
Structure-Oriented Environments. ACM Transactions on
Programming Languages and Systems, To appear.
- Adrian Koren, Identifying Type Changes in a Collection of
Evolving Types. Masters project report, Computer Science
Department, University of Massachusetts, Amherst, May 1992
- Barbara Staudt Lerner. Extending the Notion of Type
Conformance to Interfaces and Type Systems. OOPSLA '93
Workshop on Supporting the Evolution of Class Definitions,
September 1993, Washington, DC.
- Demonstration available upon request.
The Arcadia Project
Last modified: Wed Nov 30 14:44:52 1994