Cloud Computing is an emerging new computing paradigm which is developed out of service-orientation, grid computing, parallel computing, utility computing, autonomic computing, and virtualization paradigms. Both industry and academia have experienced its rapid growth and are exploring full usage of its potentials to maintain their services provided to customers and partners. In this context, a key aspect to investigate is how to architect or design cloud-based application that meet various system requirements of customers’ needs. In this thesis, we have applied the systematic literature review method to explore the main concerns when architecting for the cloud. We have identified, classified, and extracted existing approaches and solutions for specific concerns based on the existing research articles that focus on planning and providing cloud architecture or design for different concerns and needs. The main contribution of the thesis is a catalogued architecture solutions for managing specific concerns when architecting for the cloud.

The history of university, college, and high school campuses is eventful with man-made tragedies ensuing a tremendous loss of life. Virginia Tech's April 16 shooting ignited the discussion about balancing openness and safety in open campus environments. Existing campus safety solutions are characterized by addressing bits and pieces of the problem. The perfect example is the recent influx in demand for Electronic Notification Systems (ENS) by many educational institutions following the tragedies at Virginia Tech and Northern Illinois University. Installing such systems is important, as it is an essential part of an overall solution. However, without a comprehensive, innovative understanding of the requirements for an institution-wide solution that enables effective security control and efficient emergency response, the proposed solutions will always fall short. This dissertation describes an architecture for SINERGY (campuS sItuational awareNess and Emergency Response manaGement sYstem) – a Service-Oriented Architecture (SOA)-based network-centric system of systems that provides a comprehensive, institution-wide, software-based solution for balancing safety and openness on any campus environment. SINERGY architecture addresses three main capabilities: Situational awareness (SA), security control (SC), and emergency response management (ERM). A safe and open campus environment can be realized through the development of a network-centric system that enables the creation of a COP of the campus environment shared by all campus entities. Having a COP of what goes on campus at any point in time is key to enabling effective SC measures to be put in place. Finally, common SA and effective SC lay the foundation for an efficient and successful ERM in the case of a man-made tragedy. Because this research employs service orientation principles to architect SINERGY, this dissertation also addresses a critical area of research with regards to SOA; that area is SOA security. Security has become a critical concern when it comes to SOA-based network-centric systems of systems due the nature of business practices today, which emphasize dynamic sharing of information and services among independent partners. As a result, the line between internal and external organization networks and services has been blurred making it difficult to assess the security quality of SOA environments. In order to do this evaluation effectively, a hierarchy of security indicators is developed. The proposed hierarchy is incorporated in a well-established evaluation methodology to provide a structured approach for assessing the security of an SOA-based network-centric system of systems. Another area of focus in this dissertation is the architecting process. With the advent of potent network technology, software/system engineering has evolved from a traditional platform-centric focus into a network-centric paradigm where the “system of systems” perspective has been the norm. Under this paradigm, architecting has become a critical process in the life cycle of software/system engineering. The need for a structured description of the architecting process is undeniable. This dissertation fulfills that need and provides a structured description of the process of architecting a software-based network-centric system of systems. The architecting process is described using a set of goals that are specific to architecting, and the associated specific practices that enable the realization of these goals. The architecting process description presented herein is intended to guide the software/system architects. / Ph. D.

The National Weather Service (NWS) is responsible for ensuring that the U.S is a weather ready nation. The mission of the NWS focuses on protecting the lives and property of those in the U.S, while also enhancing the national economy. The number of high-impact weather events have increased over the past decades, suggesting a need for a more effective NWS. This paper focuses on improving the NWS by following the systems engineering approach and using system architecting principles.

Innovating is essential to sustained industrial growth and profitability. But experience amply demonstrates how difficult innovation is, especially for large companies. The synthesis of valued offerings by aligning customer needs with technology possibilities lies at the heart of innovation. System architects working at the strategic level are ideally positioned, as a consequence of their experience and training, to play a key and even a leadership role in enabling, energizing, and leading this synthesis. The scope of the architecting effort must include the process architecture of the entire value chain as well as the more conventional product architecture to address all potential wellsprings of innovation. This paper outlines an architecture-centric approach to innovation, based on the concept of the system platform architecture. / Center for Innovation in Product Development, MIT

Architecture is a key factor to the success of the software product, but at least the state of art is not the state of practice. The connection between the completed system and the architecture has often been damaged after the original implementation. Reverse architecting is a method to recover the software architecture by analyzing the artifact. Since reverse architecting is not mature yet, the paper studies methods, tools, and major issues which hinder the person performing reverse architecting all together from knowing whether the reverse architecting method is repeatable and possible to apply on the different releases of the same product.

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

Flera företag använder sig än idag av mjukvarusystem som är uppbyggda med äldre mjukvaruarkitektur som den monolitiska. Ett av dessa företag är Consid vars personalsystem är uppbyggt med det utdaterade ramverket klassisk ASP och där användargränssnitt samt logik kan direkt kommunicera med varandra. Detta medför begränsningar som uppstår till följd av brister i modularitet på grund av valet av mjukvaruarkitektur, vilket försvårar vidareutveckling och ändringar i ett system. Dessa begränsningar påverkar i sin tur parametrar som prestanda, skalbarhet, säkerhet, robusthet samt integrering med modernare tekniker.  I denna rapport presenteras en litteraturstudie samt en semistrukturerad intervjustudie, i syfte att undersöka vilka mjukvaruarkitekturer som är lämpliga att implementera vid en modernisering av en monolitisk mjukvaruarkitektur. Arbetet diskuterade också vilka utmaningar som kan uppstå vid en sådan modernisering och hur de hanteras på ett effektivt sätt. Ett bedömningsschema med önskvärda parametrar, med avseende på skalbarhet, prestanda, säkerhet och robusthet, togs fram för att underlätta avgörandet vid val av mjukvaruarkitektur. Utifrån detta, beslutades det att en prototyp med en REST-baserad arkitektur skulle implementeras och utvärderas.  Resultatet av prototypen, till följd av re-architecting, visade en ökad modularisering av mjukvaruarkitekturen. I jämförelse mot med det tidigare systemet har den nya prototypen ingen större påverkan på prestanda i form av responstid. Däremot bidrog prototypen till förbättrad skalbarhet när det gäller vidareutvecklingen av systemet, eftersom det förenklar införandet av ny funktionalitet. Prototypen hade också högre säkerhet genom att isolera lager ifrån varandra samt dölja underliggande detaljer i implementationen. Dessutom blev prototypen inte bara mer robust till följd av modulariseringen, men även enklare att utföra integrationstester samt destruktiva tester mot. / Several companies still use software systems that are built with older software architecture such as the monolithic one. One of these companies is Consid, whose personnel system is built with the outdated framework Classic ASP and where the user interface and logic can directly communicate with each other. This entails limitations that arise because of shortcomings in modularity due to the choice of software architecture, which complicates further development and changes in a system. These limitations in turn, affect parameters such as performance, scalability, security, robustness, and integration with modern technologies. In this work, a literature study was conducted as well as a semi-structured interview study in order to investigate which software architectures are suitable to implement when a modernization of a monolithic software architecture, is carried out. The work also discussed the challenges that may arise in a modernization of the software architecture and how they are handled efficiently. An assessment scheme with desirable parameters regarding scalability, performance, security, and robustness, was developed to facilitate the decision in the choice of software architecture. Based on this, it was decided that a prototype with a REST-based architecture would be implemented and evaluated. The result of the prototype, following re-architecting, showed an increased modularization of the software architecture. Compared to the previous system, the new prototype has no major impact on performance in terms of response time. However, the prototype contributed to better scalability in the further development of the system as it simplifies the introduction of new functionality. The prototype also had higher security by isolating layers from each other and hiding the underlying details in the implementation. In addition, the prototype not only became more robust because of the modularization, but also easier to perform destructive tests against.

Building systems that satisfy the given requirements is a main goal of software engineering. The success of this process relies largely on the presence of an adequate architectural design. Traditional paradigms deal with requirements separately from design. Our empirical studies show that crossing the boundary between requirements and design is difficult, existing tools and methods for bridging the gap inadequate, and that software architects rely heavily on experience, prior solutions, and creativity. Current approaches in moving from requirements to design follow two schools. One is architecture-centric, focused on providing assistance to architects in reuse. The other is requirements-centric, and tends to extend established development frameworks and employ mappings to transition from requirements to architecture. Jackson indicates that clear understanding of requirements (the problem) is crucial to building useful systems, and that to evolve successfully, their design must reflect problem structure. Taylor et al. argue that design is the central activity in connecting requirements and architecture. Nonetheless, existing approaches either overlook underlying structure of requirements or design considerations. This dissertation presents a novel theory enabling requirements structuring and design analysis through requirements refinement and refactoring. The theory introduces a refinement process model operating on four abstraction levels, and a set of refactoring operators and algorithms. The method works in small, well-guided steps with visible progress. The theory provides a basis for designers to analyze and simplify requirement descriptions, remove redundancy, uncover dependencies, extract lower-level requirements, incorporate design concerns, and produce a system decomposition reflecting the underlying problem structure. A design built on top of this decomposition is better suited for evolution than one created without explicit structural analysis. The theory is validated on an industrial-sized project, wherein a suitable system decomposition is produced and a comparison made to a conventionally-devised solution. Examples demonstrate that the theory handles changes incrementally. It is explained how the theory addresses the existing challenges in going from requirements to design and supports fundamental software engineering principles. The method is assessed against common validation criteria. The approach is compared with prominent related work.

Building systems that satisfy the given requirements is a main goal of software engineering. The success of this process relies largely on the presence of an adequate architectural design. Traditional paradigms deal with requirements separately from design. Our empirical studies show that crossing the boundary between requirements and design is difficult, existing tools and methods for bridging the gap inadequate, and that software architects rely heavily on experience, prior solutions, and creativity. Current approaches in moving from requirements to design follow two schools. One is architecture-centric, focused on providing assistance to architects in reuse. The other is requirements-centric, and tends to extend established development frameworks and employ mappings to transition from requirements to architecture. Jackson indicates that clear understanding of requirements (the problem) is crucial to building useful systems, and that to evolve successfully, their design must reflect problem structure. Taylor et al. argue that design is the central activity in connecting requirements and architecture. Nonetheless, existing approaches either overlook underlying structure of requirements or design considerations. This dissertation presents a novel theory enabling requirements structuring and design analysis through requirements refinement and refactoring. The theory introduces a refinement process model operating on four abstraction levels, and a set of refactoring operators and algorithms. The method works in small, well-guided steps with visible progress. The theory provides a basis for designers to analyze and simplify requirement descriptions, remove redundancy, uncover dependencies, extract lower-level requirements, incorporate design concerns, and produce a system decomposition reflecting the underlying problem structure. A design built on top of this decomposition is better suited for evolution than one created without explicit structural analysis. The theory is validated on an industrial-sized project, wherein a suitable system decomposition is produced and a comparison made to a conventionally-devised solution. Examples demonstrate that the theory handles changes incrementally. It is explained how the theory addresses the existing challenges in going from requirements to design and supports fundamental software engineering principles. The method is assessed against common validation criteria. The approach is compared with prominent related work.

This thesis proposes an advanced architecting methodology. This methodology allows for the sizing and optimization of aircraft system architecture concepts and the establishment of subsystem development strategies. The process is implemented by an architecting team composed of subsystem experts and architects. The methodology organizes the architecture definition using the SysML language. Using meta-modeling techniques, this definition is translated into an analysis model which automatically integrates subsystem analyses in a fashion that represents the specific architecture concept described by the team. The resulting analysis automatically sizes the subsystems composing it, synthesizes their information to derive architecture-level performance and explores the architecture internal trade-offs. This process is facilitated using the Coordinated Optimization method proposed in this dissertation. This method proposes a multi-level optimization setup. An architecture-level optimizer orchestrates the subsystem sizing optimizations in order to optimize the aircraft as whole. The methodologies proposed in this thesis are tested and demonstrated on a proof of concept based on the exploration of turbo-electric propulsion aircraft concepts.