Systems Engineering
- Overview: Systems Engineering
- Overview: System Engineering Process
- Step 1: Requirements Analysis
- Step 2: System Analysis and Control
- Step 3: Functional Analysis Allocation
- Step 4: Design Synthesis
- Systems Engineering Activity Map
- Anti-Tamper (AT)
- Capability Development Document
- Capability Production Document (CPD)
- Concept of Operations (CONOPS)
- Configuration Baselines
- Configuration Management (CM)
- Functional Area Analysis (FAA)
- Functional Needs Analysis (FNA)
- Functional Solutions Analysis (FSA)
- Functional Architecture (FA)
- Initial Capabilities Document (ICD)
- Initial Technical Review (ITR)
- Interface Management
- Interfaces
- Measures of Effectiveness (MoE)
- Modeling and Simulation (M&S)
- Modular Open Systems Approach
- Open-Standards System Architecture
- Operational Requirements
- Operational Requirements Document
- Physical Architecture (PA)
- Process Inputs/Outputs/Loops
- Requirements Management 
- Software Planning in the SEP
- Standardization
- System Design Review (SDR)
- System Requirements Document (SRD)
- System Requirements Review (SRR)
- System Safety Engineering
- System Verification Review (SVR)
- System of Systems (SoS) Engineering
- Systems Engineering Activity Map
- Systems Engineering Management Plan (SEMP)
- Systems Engineering Plan (SEP)
- Systems Engineering Standards
- SE Technical Review (SETR) Process
- Technical Baseline
- Technical Performance Measurement
- Technical Reviews and Audits
- Trade Studies
- Validation and Verificatio (V&V)
- Verification Process
- Work Breakdown Structure (WBS)
Systems Engineering
Modular Open Systems Approach

Modular Open Systems Approach (MOSA) is an integrated business and technical strategy for assessment and implementation of open systems in the DoD. An open system is a system that employs modular design tenets, uses widely supported and consensus-based standards for its key Interfaces, and is subject to Validation and Verification, including Test and Evaluation, to ensure the openness of its key interfaces.  

An open systems design is a design approach for developing an affordable and adaptable open system. It derives inputs from both the technical management processes and technical processes undertaken within the systems engineering and other life-cycle processes, and in turn impacts these processes. The open systems design strategy should be implemented as part of the program's overall technical approach and becomes an integral part of the program's Systems Engineering Plan (SEP) and a summary in their Acquisition Strategy.  

A key to the design of open systems is the use of open standards. The DoD Information Technology Standards Registry (DITSR) mandates the minimum set of standards and guidelines for the acquisition of all DoD systems that produce, use, or exchange information.  

Programs should design their system based on adherence to the following five (5) MOSA principles:
  1. Establish an Enabling Environment: Program Manager (PM) establishes supportive requirements, business practices, and technology development, acquisition, test and evaluation, and product support strategies needed for effective development of open systems.
  2. Employ Modular Design: Effective modular design is contingent upon adherence to four major modular design tenets:
    1. Cohesive (contain well-focused and well-defined functionality)
    2. Encapsulated (hide the internal workings of a module's behavior and its data)
    3. Self-contained (do not constrain other modules)
    4. Highly binned (use broad modular definitions to enable commonality and reuse)
  3. Designate Key Interfaces: Interfaces should be group into key and non-key interfaces. Such distinction enables designers and configuration managers to distinguish among interfaces that exist between technologically stable and volatile modules, between highly reliable and more frequently failing modules, between modules that are essential for net-centricity and those that do not perform net-centric functions, and between modules that pass vital interoperability information and those with least interoperability impact.
  4. Use Open Standards: Interface standards should be well defined, mature, widely used, and readily available.
  5. Certify Conformance: Openness of systems is verified, validated, and ensured through rigorous and well-established assessment mechanisms, well-defined interface control and management, and proactive conformance testing. The program manager, in coordination with the user, should prepare validation and verification mechanisms such as conformance certification and test plans to ensure that the system and its component modules conform to the external and internal open interface standards allowing plug-and-play of modules, net-centric information exchange, and re-configuration of mission capability in response to new threats and evolving technologies.


Open systems characteristics and principles address:



AcqLinks and Reference:
- Defense Acquisition Guidebook (DAG) - Chapter 4.4.11
- DoD Instruction 5000.02 "Operation of the Defense Acquisition System" - 8 Dec 2008
- Open System Architecture (OSA) Contract Guidebook for Program Managers - June 13
- Open Systems Architecture (OSA) Contract Guidebook for Program Manager - Dec 11
- Program Managers Guide to Open Systems - Sept 2004
- MOSA Program Assessment and Review Tool (PART)
- Website: OSD Systems Engineering - Open Systems Approach (MOSA)


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