1. Development and Use of Architectures in System Engineering Rosalind Lewis USC-CSSE Workshop October 2007 © 2007 The Aerospace Corporation Motivated by “System and Software Engineering: Architecture Models Reconciliation”

2. 2 Issues Raised by Systems & Software Architecture Reconciliation* Development budget spent on software and software-related activities – functional richness and adaptability expected in modern products is practically achievable (with current technology) only through large software developments – structure of these systems is increasingly multilayer rather than hierarchical Systems engineering and system architecture descriptions are often not well suited to support complex software developments Integration problem within the context of the systems engineering process – among design representations, specifically architecture representations – examines reconciliation methods specific to systems and software architecture *Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.

3. 3 Composition VS Layered Hierarchies* *Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.

4. 4 Formal Definitions from the Community “Architecture,” either of a system or of a piece of software, is taken to mean its fundamental organization or structure. Architecture reflects basic decisions about what a thing (system or piece of software) will consist of. - Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.

5. 5 Some Architecting Scenarios

6. 6 Enabling Concepts Functional Concepts Architecture ICD STAR Sys & Tech Views MSFD Scenario System Spec Verification Plan Seg X SpecSeg Y SpecSeg Z Spec Ops Views TEMP SPG Air Force CONOPS TRD JCD CDD CPD AoA Interface Docs Operational Concept CONOPS Government Users / Operators Government Acquisition Contractor Test Plan Seg X-1 SpecSeg Y-1 SpecSeg Z-1 Spec Determining User Needs

7. 7 Three Views of the Architecture Operational What should the architecture do? Concept Opn’l Node Connectivity Information Exchanges Activity Model Etc. Technical What governs the system design? Technology Standards System How will the architecture be built? System Node Connectivity System Info Exchanges System interfaces Etc. Vision Implementation Enablers System Specifications Common Format Enables Shared Understanding Across Interfaces: System Discipline (INT) Organization

8. 8 Functional Requirements Analysis Notional Architecture(s) Performance Requirements Analysis Function 1 Function 2 Function 3 Function 4 Function 5 Functional MoE 1 MOP 1 MoE 3 MoE 2 MOP 2MOP 3 MOP 4 Measures of Effectiveness Measures of Performance = funct (MOP 4) = funct (MOP 2,MOP 3) = funct (MOP 1) D/L Mission Data Unprocessed Data U/L Scheduled Tx User Data & Prioritization Processed Data Operational Requirements Requirements Analysis Functional Analysis / Allocation Requirements Loop System Analysis & Control (Balance) Synthesis Design Loop Verification Translating from Operational (Capability) to System Requirements

9. 9 4.4 Architectural Design Process Source: INCOSE SE Handbook

10. 10 Synthesis Functional-to-Physical Mapping Synthesis transforms the functional architecture into a physical architecture by defining the physical components needed to perform the functions identified in Functional Analysis. – Each part of the physical architecture must meet at least one functional requirement, and any part may support many functions. – The physical architecture is the basic structure for generating the specifications and baselines. System Sub- System 1 Sub- System 2 Sub- System 3 Sub- System 4 Sub- System 5 PHYSICAL ARCHITECTURE FUNCTIONAL ARCHITECTURE Functions Function 1 Function 2 Sub-function 2-1 Sub-function 2-2 Sub-function 2-3 Sub-function 2-4 Sub-function 2-5 Function 3 Sub-function 3-1 Sub-function 3-2 Function 4 Sub-function 4-1 Sub-function 4-2 x x x x x x x x x x x

11. 11 Example: Household Lighting – Functional Decomposition Control Room Illumination Provide Power Source Provide User Control Contain Controls Illuminate Provide On/Off Control Provide Variable Control Household Power Lines Receive Power Provide Light Source Orient Light Source Shade Light Source Lamp Simple Switch Dimmer Switch Housing & Faceplate

12. 12 Space Communications Architecture Communications architecture consists of many individual communications links. Launch Phase Satellite In Orbit Sensor Satellite Uplink TT&C Downlink Mission Data TT&C Return Link Forward Link Sensor Satellite Relay Satellite Relay Satellite Relay Satellite Return Link Forward Link Crosslinks or Intersatellite Links Return Link Forward Link Intersatellite Links Uplink Downlink Mission Data Ground Stations TT&C Uplink Downlink

13. 13 Elements of Systems Effectiveness (a space communication example) Constellation Availability – Percentage of time that the constellation is fully functional Connectivity – How data flows from space to the user Robustness – Ability to deal with failures and threats and continue to be effective

14. 14 Practical Problem of Selecting Most Cost-Effective Alternative Effectiveness Cost Effectiveness Cost ALT 1 ALT 2 ALT 4 ALT 3 Threshold Decision-maker considers: Decision-maker considers: - Cost * - Cost * - Effectiveness* - Effectiveness* - Politics - Politics - Force structure - Force structure - Schedule - Schedule - Risk* - Risk* - Flexibility (scenarios)* - Flexibility (scenarios)* - Budget (affordability) - Budget (affordability) -... -... *Covered in AoA *Covered in AoA

15. 15 Alternatives Description and Concepts of Operation (CONOPs) A Concept of Operations (CONOPs) should be developed for each design alternative Describe the operation and maintenance of the system and how it will be deployed during operations Identify staffing levels to operate and support the system Discuss how the system will be operated and maintained and its interactions with other operating systems Identify how the system fits into the existing (e.g. command and control) system and identify any unique requirements Describe the basing mode and any special requirements for basing, support, etc. Additional description may include: – Functional decomposition per system per alternative – Functional flow and typical timeline of alternatives

16. 16 Architecting and Engineering Functions Req’t Generation Users & Operators Very Broad Needs Performance Requirements Subsystem Requirements Production & Deployment Architecture Definition Concept Exploration Design and Development Architecting Architecting & Engineering

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