Affiliations: National Institute of Standards and Technology,
Maryland, USA | Intelligent Systems Technology Inc., Santa Monica, CA,
USA
Abstract: Service-Oriented Architectures (SOA) provide the first widely
applicable approach to tying together diverse
"stovepipe" (or "silo")
systems. They are, therefore, a "pure" example of how
to build Systems of Systems (SOS). With the growing interest in and increasing
number of implementations of SOAs, there is a pressing need for measures and
metrics that can help SOA developers (Chief Architects or Program Managers) in
predicting potential problems in the development/evolution of their SOA system.
For SOA-based systems, such assistance is vital since their success depends on
melding appropriate technologies and design with organizational
characteristics, customer profiles, and functions provided, a Systems of
Systems (SOS) concern. This paper discusses an ongoing effort in this area. In
addition to providing a useful tool, this effort is technically significant for
three key reasons. First, SOA specification and assessment requires
consideration of technology factors and their relationships to the
organization, and to individual information consumers. Essentially, these are
related to metrics for systems engineering. Second, requirements (e.g., ease of
use, flexibility) are defined in terms of system characteristics that can be
modeled and measured. Thus, the system is defined by a set of evolving models
and metrics that allow continual evaluation of progress towards eliminating
problems. Third, since requirements are initially expressed with coarse-grained
conceptual models, measurement of the characteristics of these models can
indicate areas where the system might not meet some requirement, thereby
allowing early corrective action. Thereafter, more refined models, can be
developed to track the success of corrective actions. This paper provides a
background on SOA, challenges for SOA metrics, and proposes a model-based
metrics framework for evaluating SOAbased systems on an ongoing basis. It
provides exemplar metrics and measures for SOA, and discusses several
approaches to metrics quantification and presentation.
