Systems Integration

Definition: Systems integration is the composition of a capability by assembling elements in a way that allows them to work together to achieve an intended purpose.

Keywords: acquisition, capability, people, process, program, reward, solution, SoS, system of systems, systems integration

MITRE SE Roles and Expectations: MITRE systems engineers (SEs) are expected to identify integration and interoperability challenges and create integration strategies that meet the business/mission needs of end users and their stakeholders. MITRE SEs develop and evaluate integration and interoperability options and observe and assess integration testing. SEs are expected to address integration and interoperability issues associated with the system, including technical, programmatic, social, and business dimensions.


Systems integration creates a mission capability by composing subcomponents of the capability. It is the logical next step between design and development, and testing, verification, validation, and deployment. Always important, integration is increasingly critical to success as the programs MITRE supports migrate to service-oriented, composable-capability architectures.

After components are developed, they must be integrated with or in the environment in which they are expected to operate. The assembled system is then tested to verify that it performs in accordance with its requirements.

There are different forms of integration. Vertical integration is when the components of a system, developed by a single acquisition program, are integrated to produce the desired capability. Horizontal integration creates new capabilities across individual systems developed by different acquisition programs. Often, the individual systems were originally developed for different customers and purposes. One of the first government resources available on engineering these types of systems is the Systems Engineering Guide for Systems of Systems [1].

Articles in This Topic

This topic's articles cover the key aspects of systems integration: identifying and assessing integration and interoperability (I&I) challenges, developing and evaluating I&I solutions, assessing integration testing approaches, and interface management.

The article Identify and Assess Integration and Interoperability (I&I) Challenges describes the dimensions of integration and interoperability, the SE's role in addressing them, and best practices and lessons learned in recognizing and evaluating their challenges.

Once the I&I challenges are understood, SEs are expected to develop and evaluate strategies to address them and to recommend a way forward. The article Develop and Evaluate Integration and Interoperability (I&I) Solution Strategies discusses the second half of the thread from I&I challenges to solutions. Read the articles together to understand the entire challenge-to-solution thread.

Integration testing often poses significant challenges. The article Assess Integration Testing Approaches discusses the problems associated with testing approaches, suggests possible testing strategies and when integration testing, system-of-system testing, or other approaches are appropriate for a program.

Managing interfaces also presents special challenges to systems integration. The article Interface Management discusses general principles and best practices of managing interfaces, with special attention to doing so in a complex, interconnected, service-based enterprise, where the consequences of interface decisions can have significant ripple effects.

For complex integration environments, see the Systems Engineering Strategies for Uncertainty and Complexity article in the SEG's Enterprise Engineering section.

References and Resources

  1. Director, Systems and Software Engineering, Deputy Under Secretary of Defense (Acquisition and Technology), August 2008, Systems Engineering Guide for Systems of Systems, Ver. 1.0, Office of the Under Secretary of Defense, Acquisition, Technology and Logistics (AT&L), Department of Defense (DoD), Washington, D.C.

Additional References and Resources

CMMI Product Team, November 2010, "CMMI® for Acquisition, Ver. 1.3, Technical Report CMU/SEI-2010-TR-032, Software Engineering Institute (SEI), Pittsburgh, Pa.

Dahmann, J. S., J. Lane, and G. Rebovich, Jr., November 2008, "Systems Engineering for Capabilities," CrossTalk—The Journal of Defense Software Engineering.

Hybertson, D. W., 2009, Model-Oriented Systems Engineering Science, New York, Taylor & Francis.

Kelley, M., and R. Kepner, August 2008, Achieving Effective Results in Acquisition: Guidelines for Recommended Action, The MITRE Corporation.

White, B. E., March 23–26, 2009, "Complex Adaptive Systems Engineering (CASE)," 2009, 3rd Annual IEEE Systems Conference, Vancouver, BC.


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