Computing has evolved from isolated machines, providing calculative support of applications, toward communication networks that provide functional support to groups of people and embedded systems. Perhaps, one of the most compelling feature and benefit of computers is their overwhelming computing efficiency. Today, we conceive distributed computational systems of an ever-increasing sophistication, which we then apply in various settings – critical support functions of our society just to name one important application area. The spread and impact of computing, in terms of so-called information society technologies, has obviously gained a very high momentum over the years and today it delivers a technology that our societies have come to depend on. To this end, concerns related to our acceptance of qualities of computing, e.g., dependability, are increasingly emphasized by users as well as vendors. An indication of this increased focus on dependability is found in contemporary efforts of mitigating the effects from systemic failures in critical infrastructures, e.g., energy distribution, resource logistics, and financial transactions. As such, the dependable function of these infrastructures is governed by means of more or less autonomic computing systems that interact with cognitive human agents. However, due to intricate system dependencies as well as being situated in our physical environment, even the slightest – unanticipated – perturbation in one of these embedded systems can result in degradations or catastrophic failures of our society. We argue that this contemporary problem of computing mainly is due to our own difficulties in modeling and engineering the involved system complexities in an understandable manner. Consequently, we have to provide support for dependable computing systems by means of new methodologies of systems engineering. From a historical perspective, computing has evolved, from being supportive of quite well defined and understood tasks of algorithmic computations, into a disruptive technology that enables and forces change upon organizations as well as our society at large. In effect, a major challenge of contemporary computing is to understand, predict, and harness the involved systems’ increasing complexity in terms of constituents, dependencies, and interactions – turning them into dependable systems. In this thesis, we therefore introduce a model of open computational systems, as the means to convey these systems’ factual behavior in realistic situations, but also in order to facilitate our own understanding of how to monitor and control their complex interdependencies. Moreover, since the critical variables that govern these complex systems’ qualitative behavior can be of a very elusive nature, we also introduce a method of online engineering, whereby cognitive agents – human and software – can instrument these open computational systems according to their own subjective and temporal understanding of some complex situation at hand.

There is an emerging field in the design and development of complex systems, where systems are built upon components which in themselves are large scale systems – system of systems. Among other things, the system of systems viewpoint emphasises on open complex systems. In this thesis, the model of open computational systems is used to convey the constituents, dependencies, and interactions of such complex distributed systems. These open complex systems are exposed to critical events, occurring in the systems execution environment. Moreover, these events may have negative effects on the system at hand, resulting in system behaviour diverging from intended. Also, to take all possible affecting events in consideration when designing the system is impossible. By being able to instrument the system at hand in real time, i.e. online, one may be able to compensate the effects caused by critical events. However, to enable online instrumentation, one needs a supporting methodology which handles issues of an online nature and supporting technologies. In this thesis, this support is enabled by the methodology of online engineering and the technology of visualization. Furthermore, these instrumentations can be performed by cognitive agents – both human and software – which may explore and refine a specific system in conformance with their own, or cooperative, agendas and qualitative goals. To be able to perform the instrumentation, the cognitive agents need to be able to observe the phenomenon at hand to gain situation awareness, which in itself lies as a foundation for the decision process, carried out during the instrumentation phase. With this in mind, one quickly realizes the importance of enabling observation of open computational systems for both human and software cognitive agents. If human cognitive agents are involved in applying the methodology; the requirements on how the system is represented for the observing human agent – how the system is visualized – grows even more important. In this thesis, we emphasise visualization technology as a supporting technology for human cognitive agents in their observation process. By providing human cognitive agents with visualization technology, we may enhance the result of their observation process and thereby also increase the possibility to reach their qualitative goals. Hence, visualization of open computational systems affects a human cognitive agent’s situation awareness, which in itself lies as the foundation for the decision making process on instrumentation of the specific system at hand in conformance with the agent’s qualitative goals. This thesis will present an evaluation of a supporting tool for visualization of systemic qualities in open computational systems. Such tool must supply functions which convey the set of requirements put forward by the selected model, method, and technology. Moreover, the evaluation will be accompanied by appropriate recommendations for improvement of such a tool.

Our modern information society provides us with a tremendous amount of information. Several issues have surfaced due to the complexity inherent in the handling of the information systems. One of the most important issues is that of providing an architecture and methodology that provide for the development and maintenance of complex, distributed information systems. As the information flow and quantity hinders us from having qualitative information when needed, the architecture must address the reach, richness and value of the information. Network-centric warfare is a problem domain that has been initiated to meet the power of information. To be able to support such continouos sustainability, a robust network infrastructure is critical. A systemic perspective on network-centric environments as well as a technical perspective on network-centric environment shows that, although promising, contemporary implementations having a service-oriented architecture lack support for physical scalability and a cognitive decoupling that would provide for multiple users acting on the same environment. Consequently, a service-oriented layered architecture for communicating entities is presented where these issues are addressed. For verification, a demonstrator is developed upon a service-oriented layered architecture for communicating based on a network-centric warfare scenario.

By means of a systemic approach toward analysis and design of complex systems, we introduce the issue of implementing open computational systems on service-oriented architectures. We start by studying general systems theory, as it accounts for analysis and modeling of complex systems, and then compare three different implementation strategies toward system implementation. As such, the comparison is grounded in the notion of supporting architectures and, more specifically, in the practical case of a service-oriented layered architecture for communicating entities (SOLACE). / More material can be found on http://www.soclab.bth.se