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Flow Structures and the FSQ Framework: A Basis for System Survivability Specification and Design. CERT/Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh, PA 15213 Sponsored by the U.S. Department of Defense. Eight System Trends.
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Flow Structures and the FSQ Framework: A Basis for System Survivability Specification and Design CERT/Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh, PA 15213 Sponsored by the U.S. Department of Defense
Eight System Trends • Ever larger-scale meta-system integration • Massive interconnection • Wholesale interoperability (think XML) • Shift to web services (think .NET) • Dynamic adaptation of functionality • Escalating demand for quality attributes • Increasing consequences of compromise • Growth of complexity impacts human control
The CERT Survivable Network Analysis (SNA) Method Organizational Mission Threat Environment Essential Service Flows Intrusion Flows Architecture Traces Architecture Traces Essential Components Compromisible Components • Flow/trace based method • Successful application • Motivates deeper look at flows for • survivability specification and design Architecture Softspots Survivability Improvements
Three Critical Questions • In the world of shifting meta-system integration and connectivity... • What is the basis for intellectual control over system development and operation? • What is the stable engineering foundation for specification and design? • What is the vehicle for survivability analysis and design?
Flow Structures • Goal • Create stable and practical engineering foundations for the meta-system world of shifting system structures and connections • Observations • Organizational missions are embodied in user task flows that are satisfied by system services • Flows are stable anchors for specification, design, verification, and implementation
Flow Structures • Semantic foundations • Scale-free, referentially-transparent procedural and concurrent primitives refined, abstracted, and verified through compositional methods • Engineering usage • Defined as user-function task-flow specifications annotated with required quality attributes • Refined into designs of system service uses • Relational specifications account for all possible outcomes; a specification is a set of flows
The Flow-Service-Quality Framework • Semantic foundations • FSQ is an architecture template for managing execution of Flow Structure functionality and quality attributes based on dynamic feedback control • Engineering usage • FSQ architecture mediates Flow Structure function and quality specifications with respect to dynamic system service function and quality properties, to control functional flow execution and satisfy quality specifications
FSQ Framework: Operations View FSQ Framework: Enginering View
Current Research • Survivability attributes • Focus on incorporation of survivability attributes into Flow Structure and system service specifications and designs • Computational survivability • Focus on treating survivability as a function to be computed, with dynamic system responses to varying survivability properties for flow management