System ATAM and SoS Architecture Evaluation
Software intensive systems often suffer severe integration and operational/behavioral problems due to lack of consistency between the system and software architectures in addressing system quality attributes. This often times results in re-architecting and re-designing efforts, and operational failures, which significantly impact system cost, schedule and mission effectiveness. These problems are further exacerbated in a system of systems (SoS) context.
Major system and software elements that are developed for an SoS may each have their own architecture documentation, perhaps be built with diverse tools and notations, and be developed concurrently by different contractors. SoS development is usually done in a number of phases, with roughly 18 months to 2 years separation between phases. This makes it difficult to evaluate whether the integrated systems composed of many of these elements will satisfy their functional and quality attribute requirements.
We are developing methods and approaches for evaluating system and SoS architectures to ensure early identification of quality attribute inconsistencies and architectural risks:
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Architecture Tradeoff Analysis Method - for Systems. We are expanding the scope of the Architecture Tradeoff Analysis Method (ATAM) so that it can be used to evaluate system architectures. There are several essential differences between ATAM for software architecture and ATAM for system architecture, specifically in the following areas: system architecture notations and specifications, additional engineering considerations, additional quality attribute concerns, additional architectural approaches, scope, the potential need for fast-tracking subject matter experts onto the evaluation team, and system ATAM lead evaluator qualifications.
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SoS architecture evaluation. SoS architecture evaluation requires a different approach than system architecture evaluation. SoS architecture evaluation uses existing mission threads that are augmented with quality attribute concerns to drive a "first pass" identification of inconsistencies across the SoS's constituent system architectures. Potentially problematic system architecture(s) are then further evaluated using the ATAM for systems.
- Mission Thread Workshop. Mission threads are used to describe the inter-platform and inter-element operations a system. Mission threads can describe: tactical operations; logistical operations; support operations; and maintenance, training, test and development operations. Mission threads serve as drivers for developing the architecture and as the basis for test cases during a verification cycle. Since architectural design is driven primarily by quality attribute requirements, the mission threads need to be augmented with quality attribute considerations. This workshop elicits quality attribute concerns for existing or new system mission threads from SoS stakeholders.
The ATAM for systems is ready to use. We encourage those who are interested in evaluating their system and software architectures to contact us.
The SoS architecture evaluation method and Mission Thread Workshop are ready to be piloted. We encourage those who are interested in evaluating their SoS architecture to contact us to discuss a piloting activity in this area.
Additional Information
Collaboration Opportunities: The SEI architecture team is looking for industrial collaborators to pilot the integrated methods and to explore the connections with existing software and system development paradigms. The SEI is also looking for collaborations exploring connections with aspects, service-oriented architecture, open source, model-driven architectures, J2EE, or .net. The SEI is also looking for partners to develop and use quality attribute models in reliability, security, scalability, usability, and testability. Of interest is the exploration of the relationship between quality attribute models, business goals, and architecture and design patterns. Contact information and additional opportunities are located on Collaboration Opportunities in Software Architecture.
Contact Information: For more information about System ATAM and SoS Architecture Evaluation, contact Mike Gagliardi.
Working with the SEI: Learn more about working with the SEI in software architecture.