The U.S. Department of Defense (DoD) System Engineering Guide for System-of-Systems Engineering (Version 1, August 2008) defines four types of systems of systems*:

• Directed: The constituent systems are integrated and built to fulfill specific purposes
• Acknowledged: The system of systems has recognized objectives, a designated manager, and resources.
• Collaborative: The managers of the constituent systems voluntarily agree to fulfill central purposes.
• Virtual: There is no central authority or centrally agreed purpose for the system of systems.

We focus our applied research efforts on the first three of those types, directed, acknowledged, and collaborative. Each one has some degree of management and calls for some level of distributed collaboration (e.g., "power to the edge"). Through distributed collaboration, the constituent elements—technical, organizational, or both—of these systems of systems can effectively respond to heterogeneous demands from a set of (often diverse) users' demands, even though those elements are independently managed and evolving.

Our research is applied, rather than basic, and opportunistic. We are looking for collaborating organizations to explore practices that lead to the successful construction and execution of systems of systems. We are seeking partners who are developing or applying new strategies embodied in practices for system-of-systems engineering.

Our research thrusts rest on a set of system-of-systems practices—a conceptual framework, methods, processes, and tools for supporting multiple dimensions of distributed collaboration. Among the practices we are exploring are the following:

• Distributed, loosely coupled collaboration promotes system-of-systems agility.
• Independent and continuous evolution means that system-of-systems behavior cannot be completely predicted.
• Influence is more important than control in getting collaboration between system-of-systems stakeholders.

Based on that set of principles (which we continue to enhance), we view the needs of those types from the viewpoints of governance, engineering, and acquisition.

• For system-of-systems governance and acquisition, we are looking at the influence and reward structures in system-of-systems collaborations, ensuring relevant stakeholder participation in decision-making, guidance on system-of-systems acquisition and evolution.
• For system-of-systems engineering, we are working toward the development life-cycle practices by leveraging research and best practices from SOA and other implementation approaches.

In applying this research to real-world situations, we are seeking collaborations with organizations that looking for system-of-systems solutions through investigations such as

• the transformation of practices for the system-of-systems engineering life cycle
• a research agenda for service-oriented architecture (SOA) that includes business, technical, engineering, and cross-cutting issues ways to leverage SOA as an enabler for net-centric operations
• identity management in SOA environments
• testing in SOA environments
• web service verification in SOA environments
• quality attributes for SOA environments
  

We also are continuing to develop a Guide to Interoperability as a resource for those who are planning, constructing, and maintaining interoperable systems of systems.

* The types of systems are also adapted from Maier, M. "Architecting Principles for Systems-of-Systems" Systems Engineering 1, 4 (1998): 267-284.