QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures
• SEI Report
Publisher
Software Engineering Institute
CMU/SEI Report Number
CMU/SEI-2006-HB-001DOI (Digital Object Identifier)
10.1184/R1/6582785.v1Topic or Tag
Abstract
This handbook documents the QUASAR (QUality Assessment of System ARchitectures) method for assessing the quality of the architecture of a software-intensive system. It begins by discussing the challenges that are faced when assessing a system's architecture and outlines the development history of the method. The next section of the handbook documents the concept of quality cases and the claims, arguments, and evidence that compose them. This is followed by a description of the teams that collaborate to perform QUASAR tasks. Next, individual tasks and associated steps performed as part of the QUASAR method are documented. Next, the work products produced by these teams when performing these tasks are described. Finally, lessons learned during the development and use of the method when assessing the quality of major subsystems during the development of a very large, software-intensive system of systems are presented. Also provided are appendices that define common quality factors and subfactors, offer reusable checklists, and give examples of quality cases. The example quality cases illustrate valid quality goals and requirements that compose claims, example architecture decisions and associated rationales that compose arguments, and the types of evidence that architects might provide.
Cite This SEI Report
Firesmith, D., Capell, P., Elm, J., Gagliardi, M., Morrow, T., Roush, L., & Sha, L. (2006, July 1). QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures. (SEI Report CMU/SEI-2006-HB-001). Retrieved September 18, 2026, from https://doi.org/10.1184/R1/6582785.v1.
@techreport{firesmith_2006,
author={Firesmith, Donald and Capell, Peter and Elm, Joseph and Gagliardi, Michael and Morrow, Timothy and Roush, Linda and Sha, Lui},
title={QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures},
month={Jul},
year={2006},
number={{CMU/SEI-2006-HB-001},
institution={Software Engineering Institute, Carnegie Mellon University},
doi={10.1184/R1/6582785.v1},
url={https://doi.org/10.1184/R1/6582785.v1},
note={Accessed: 2026-Sep-18}
}
Firesmith, Donald, Peter Capell, Joseph Elm, Michael Gagliardi, Timothy Morrow, Linda Roush, and Lui Sha. "QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures." (CMU/SEI-2006-HB-001). Software Engineering Institute, Carnegie Mellon University. Software Engineering Institute, July 1, 2006. https://doi.org/10.1184/R1/6582785.v1.
D. Firesmith, P. Capell, J. Elm, M. Gagliardi, T. Morrow, L. Roush, and L. Sha, "QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures," Software Engineering Institute, Carnegie Mellon University. Software Engineering Institute, SEI Report CMU/SEI-2006-HB-001, 1-Jul-2006 [Online]. Available: https://doi.org/10.1184/R1/6582785.v1. [Accessed: 18-Sep-2026].
Firesmith, Donald, Peter Capell, Joseph Elm, Michael Gagliardi, Timothy Morrow, Linda Roush, and Lui Sha. "QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures." (SEI Report CMU/SEI-2006-HB-001). Software Engineering Institute, Carnegie Mellon University, Software Engineering Institute, 1 Jul. 2006. https://doi.org/10.1184/R1/6582785.v1. Accessed 18 Sep. 2026.
Firesmith, Donald; Capell, Peter; Elm, Joseph; Gagliardi, Michael; Morrow, Timothy; Roush, Linda; & Sha, Lui. QUASAR: A Method for the Quality Assessment of Software-Intensive System Architectures. CMU/SEI-2006-HB-001. Software Engineering Institute. 2006. DOI: 10.1184/R1/6582785.v1. https://doi.org/10.1184/R1/6582785.v1