Software Producibility for Systems of Systems

This three-phase, three-year project, funded by the U.S. Naval Research Laboratory in conjunction with the Office of the Secretary of Defense is focused on techniques supporting model-based design of complex, heterogeneous, software-intensive systems. These techniques directly confront the heterogeneity of cyber-physical systems (CPSs) by embracing models of physical dynamics, temporal behavior, software, and networks.

There are two distinct approaches to modeling heterogeneous systems:

  1. (i) a grand unified theory (GUT) and
  2. (ii) an abstract semantics.
The former is about developing a modeling language and conceptual framework into which heterogeneous modeling languages and frameworks can be translated. The latter is about developing interfaces between heterogeneous modeling languages that are sufficient for inter-operation, but not so rich that the interface language itself becomes a modeling language. A GUT has the advantage of enabling model exchange between tools, but the disadvantage that the semantic richness that is required to be able to encompass all interesting heterogeneous modeling languages makes analysis of models difficult. An abstract semantics has the advantage of enabling composition of domain-specific modeling languages that are themselves sufficiently constrained that analysis is still possible, but the disadvantage that engineers must learn a multiciplicity of modeling languages and must understand how they interact within an abstract semantics. We propose that the advantages of the abstract semantics approach outweigh the disadvantages, and that the disadvantages can be overcome with good quality tools and training.

The approach taken in the project is to leverage well-understood concurrent models of computation (MoCs) with rigorous semantics; to compose such MoCs heterogeneously using the notion of an abstract semantics; to embrace hybrid models that combine the continuous dynamics of the physical world with the discrete dynamics of software and networks; to leverage type theoretic ontologies and behavioral type systems to ensure correct composition of heterogeneous components; to link models of behavior to models of implementations through the notion of quantity managers; to leverage semantics-preserving transformations to synthesize implementations from models; and to drive and test all ideas with carefully selected application studies.

The proposed project builds on some preliminary work done under the Berkeley project entitled Scalable Composition of Subsystems (SCOS) (agreement W911NF-07-2-0019 dated February 12, 2007), and Disciplined Design of Systems of Systems (agreement W911NF- 11-2-0038 dated August 15, 2011), funded by the Army Research Laboratory in connection with the Software-Intensive Systems Producibility Initiative (SISPI). This proposed project will build on results from these earlier project and help identify which of the results are sufficiently mature for transition into industrial practice, which require further research investment, and which should be abandoned.

"Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Office of Naval Research."

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