Mary Shaw

The architecture of a software system defines that system in terms of components and interactions, or connections, among those components. In addition to specifying the structure and topology of the system, the architecture shows the correspondence between the system requirements and elements of the constructed sytem. It addresses system-level properties such as capacity, throughput, consistency, and component compatibility. Architectural models clarify structural and semantic differences among components and their connectors. architectural definitions can be composed to define larger systems. Elements are defined independently so they can be re-used in different contexts. The architecture establishes specifications for individual elements that may be written in a conventional programming language. A number of commonly-used patterns, or idioms, are in widespread informal use; these architectural styles can be captured as general templates for families of related systems. This holds particular promise for domain-specific systems.

My current primary concerns are identifying and supporting architectural abstractions, localizing and codifying the ways components interact, and distinguishing among the various packagings of components that require different forms of interaction. A major thrust of the research is identifying suitable abstractions for architectural styles and connectors, together with language to describe them. My focus is largely pragmatic. The first goal of the work has been to identify, classify, and support a variety of components and their connections. A prototype tool now supports eight component types and six connector types. Over time, the notation will be refined and a formal base will be developed.

Research questions of interest include:

• How can software system structure be characterized? What properties matter?

• What abstractions are useful for structures, systems, and subsystems? How are the abstractions related to each other?

• What textual and graphical notations for architecture are useful to system designers?

• How do you cope when you must build a system with parts that make incompatible assumptions about their mutual interaction?

• What kinds of checking and analysis we support?

• How can we support good architectural design decisions, especially choices among architectural styles?

In addition to developing notations, models, and tools, I actively disseminate the results. These activities center on developing and presenting educational materials on software architecture. This has to date resulted in a course, a tutorial presented at ICSE 93, SIGSOFT 93, SIGSOFT 94, and the 1996 CMU summer school, and a videotape for distribution. I am also active in promoting the ideas in professional forums. Currently, the CMU software architecture group is organizing a set of model problems in the interest of sharing common examples within the research community.

References

Shaw and Garlan 96

Mary Shaw and David Garlan. Software Architecture: Perspectives on an Engineering Discipline. Prentice Hall, to appear March 1996.

Shaw et al 96

Mary Shaw, Robert DeLine, Gregory Zelesnik. ``Abstractions and Implementations for Architectural Connections.'' International Conference on Configurable Distributed Systems, May 1996 (to appear).

Shaw 96a

Mary Shaw. ``Truth vs Knowledge: The Difference Between What a Component Does and What We Know It Does.'' Proceedings of the 8th International Workshop on Software Specification and Design, March 1996 (to appear).

Shaw 96b

Mary Shaw. ``Some Patterns for Software Architecture.'' Results from Second Annual Conference on Pattern Languages of Programming, September 1995 (to be published by Prentice-Hall, 1996).

Shaw 96c

Mary Shaw. ``Software Architectures for Shared Information Systems.'' Mind Matters: Contributions to Cognitive and Computer Science in Honor of Allen Newell. Lawrence Erlbaum, to appear 1996.

Shaw 95

Mary Shaw. ``Making Choices: A Comparison of Styles for Software Architecture.'' IEEE Software, special issue on software architecture, vol 12, no 6, November 1995, pp.27-41.

Shaw et al 95

Mary Shaw, Robert DeLine, Daniel V. Klein, Theodore L. Ross, David Young, and Gregory Zelesnik. ``Abstractions for Software Architecture and Tools to Support Them.'' IEEE Transactions on Software Engineering, vol 21, no 4, April 1995, pp. 314-335.

Lane 90

Thomas G. Lane, ``Studying Software Architecture Through Design Spaces and Rules,'' Technical Report CMU/SEI-90-TR18 ESD-90-TR-219, Carnegie Mellon University, September 1990.