What is a DoD Modular Open Systems Approach (MOSA)? (5 Core Principles)

A Modular Open Systems Approach (MOSA) is becoming critical in Department of Defense (DoD) systems. If you're unfamiliar with this critical system design approach (or need a little brush-up) you're in the right place (and should totally keep on reading to discover the 5 core principles).

But first, a few quick basics. MOSA is a business and technical strategy for easily developing new defense systems or modernizing existing ones. This will help the Department of Defense provide joint combat capabilities required for 21st century warfare.

MOSA also provides the ability to support and evolve these 21st century capabilities over their total life-cycle.

MOSA as a business strategy enables program teams to build, upgrade, and support systems more quickly and efficiently.

MOSA as a technical strategy, is focused on a system design that is modular, has well defined interfaces, is designed for change & evolution, and utilizes widely supported industry standards for key interfaces.

Preparations for applying MOSA must be initiated early in the program and acquisition planning to be most effective.

Benefits of a DoD Modular Open Systems Approach (MOSA)

The DoD looks to achieve 5 primary benefits with MOSA:

1. Improve competition – open architecture with severable modules, allowing components to be openly competed.
2. Keep technology fresh – delivery of new capabilities or replacement technology without changing all components in the entire system.
3. Incorporate innovation – operational flexibility to configure and reconfigure available assets to meet rapidly changing operational requirements.
4. Enable cost savings & cost avoidance – reuse of technology, modules, and/or components from any supplier across the acquisition life cycle.
5. Improve interoperability – severable software and hardware modules to be changed independently.

Other general benefits of using MOSA include 

• Ease of adapting to new requirements and threats
• Reduced Total Ownership Cost
• Reduced Cycle-Time
• Enabling Joint Integrated Architectures and Interoperability
• Increased competition
• Reuse of components among systems
• Risk Mitigation
• Enhanced access to cutting edge technologies & products from multiple suppliers

5 Critical MOSA Principles

Achieving these benefits requires adherence to 5 major Modular Open Systems Approach (MOSA) principles.

1. Establish an Enabling Environment
2. Employ Modular Design
3. Designate Key Interfaces
4. Use Open Standards
5. Certify Conformance

These 5 MOSA principles provide a set of indicators that could be used to assess the progress of MOSA implementation in modular architecture acquisition programs. Here's a closer look at each core principle.

1. Establish an Enabling Environment

For effective development of open systems, a program manager must establish supportive requirements, business practices, technology development, acquisition, test & evaluation, and product support strategies.

Some supportive practices needed for creating an enabling MOSA environment include

• Assigning responsibility for implementation
• Ensuring appropriate experience and training
• Continuing market research
• proactive identification
• Overcome barriers or obstacles that can slow down or undermine MOSA implementation

2. Employ Modular DesignAccurately isolating functionality during the design process will make the system easier to develop, maintain, modify, and upgrade. A system designed for modularity will provide the ability to upgrade or change functions that change or evolve quickly over time (with minor impact to the rest of the system).

An effective design process should focus on modularity first with future evolution as a later objective.

Effective modular designs include

• Correct use of disciplined definition of modular interfaces to include object oriented descriptions of module functionality
• Separated into scalable, reusable modules consisting of self-contained functional elements.
• Designed with ease of change in mind (to achieve technology transparency)
• Makes use of common industry standards for key interfaces

Speaking of key interfaces, that brings us to our next principle...

3. Designate Key Interfaces

A common misconception about modular architecture is that it focuses on control and management of all interfaces within and between systems. This would be very costly and potentially be impossible to manage hundreds or even thousands of interfaces used within the same system.

Instead, MOSA should manage interfaces by grouping them into key and non-key interfaces. This will help determine

• Technologically stable and unstable modules
• Highly reliable and unreliable (failing) modules
• Modules with the least interoperability impact and those that pass vital interoperability information

Key interfaces should utilize open standards in order to produce the most life-cycle benefits possible.

Perfect timing! This leads us onto the next principle on open standards...

4. Use Open Standards

Interface standards specify the physical, functional, and operational relationships between multiple elements (both hardware and software).

They also allow for interchangeability, interconnection, compatibility, communication, and logistics support. Market research of available standards and the application of a disciplined systems engineering process will help determine the best interface standards. 

So how do you get the most benefit from modularity in designs? Interface standards must be well defined, mature, widely used, and readily available to be effective. However in general, popular open standards bring the most benefit to the customer in terms of simple changes to the system down the road and should be the standard of choice. (There are some cases where proprietary standards are the correct choice)

As a general rule, preference should first be given to open interface standards, de facto standards next, then finally government and proprietary interface standards.

Open standards allow programs to leverage commercially developed technologies, which in return allows for increased competition. Additionally, they offer faster system upgrades with less cost and complexity. Systems can be fielded that are more affordable. 

5. Certify Conformance

The program manager (along with the end user) should prepare validation and verification mechanisms. An example is conformance certification and test plans to ensure system & component modules conform to internal and external open interfaces allowing for

• Plug-and-play of modules
• Net-centric info exchange
• Reconfiguration of mission capability in response to new DoD threats and technologies

Open systems verification & validation are a critical part of the overall configuration management processes. They'll also make sure that system components and chosen commercial products can easily be substituted with similar components from competitive sources.