Software-based system architecture has been recognized as a foundation laying out the underpinnings that are critically important for successful engineering of large-scale complex systems. In recent years, architecting has played a more crucial role in engineering network-centric system of systems. The software paradigm has been shifting from treating software as a product (SaaP) to treating software as a service (SaaS). SaaS is also referred to as the Cloud Computing, where the term "cloud" is used as a metaphor for "network". As the complexity of the architecture of network-centric software-based system of systems has increased, the description of such architecture has posed significant technical challenges. The U.S. Department of Defense (DoD) has developed the DoD Architecture Framework [DoDAF 2009a, DoDAF 2009b] for describing system architectures. IEEE proposes a Recommended Practice for Architectural Description of Software-Intensive Systems [IEEE 2000]. SEI provides high-level guidelines for Documenting Software Architectures [Clements et al 2003]. However, all of the diagrams proposed by DoD, IEEE, and SEI are two-dimensional static graphical and textual representations that do not reveal the dynamic characteristics of a system architecture. This thesis presents a conceptual framework (CF) for specifying the architecture of a network-centric software-based system of systems. The developed CF provides the beginning part of a larger research effort. The main goal of the overall research is to employ the automation-based software paradigm and to automatically generate a visual simulation model of a system architecture, with which experiments can be conducted to assess the dynamic characteristics of that architecture. The CF, developed in the research described herein, enables the automatic generation of a visual simulation model representing a system architecture. The proposed CF is evaluated in half a dozen case studies to demonstrate that it provides the necessary elements for automatic generation of a simulation model as the description of a complex system of systems architecture. / Master of Science