There is currently much UK government and industry interest towards the integration of complex computer-based systems, including those in the military domain. These systems can include both mission critical and safety critical applications, and therefore require the dependable communication of data. Current modular military systems requiring such performance guarantees are mostly based on parameters and system states fixed during design time, thus allowing a predictable estimate of performance. These systems can exhibit a limited degree of reconfiguration, but this is typically within the constraints of a predefined set of configurations. The ability to reconfigure systems more dynamically, could lead to further increased flexibility and adaptability, resulting in the better use of existing assets. Current software architecture models that are capable of providing this flexibility, however, tend to lack support for dependable performance. This thesis explores the benefits for the dependability of future dynamic systems, built on a publish/subscribe model, from using Quality of Service (QoS) methods to map application level data communication requirements to available network resources. Through this, original contributions to knowledge are created, including; the proposal of a QoS framework that specifies a way of defining flexible levels of QoS characteristics and their use in the negotiation of network resources, a simulation based evaluation of the QoS framework and specifically the choice of negotiation algorithm used, and a test-bed based feasibility study. Simulation experimentation conducted comparing different methods of QoS negotiation gives a clear indication that the use of the proposed QoS framework and flexible negotiation algorithm can provide a benefit in terms of system utility, resource utilisation, and system stability. The choice of negotiation algorithm has a particularly strong impact on these system properties. The cost of these benefits comes in terms of the processing power and execution time required to reach a decision on the acceptance of a subscriber. It is suggested, given this cost, that when computational resources are limited, a simpler priority based negotiation algorithm should be used. Where system resources are more abundant, however, the flexible negotiation algorithm proposed within the QoS framework can offer further benefits. Through the implementation of the QoS framework within an existing military avionics software architecture based emulator on a test-bed, both the technical challenges that will need to be overcome and, more importantly, the potential viability for the inclusion of the QoS framework have been demonstrated.

The current Internet presents a high barrier to entry for new service providers, due to its inability to accommodate new protocols and technologies, and lack of competition among the network providers. Recently, network virtualization has gained considerable attention as a possible solution, as it enables multiple networks to concurrently run over a shared substrate. It allows for deploying diverse network protocols and technologies customized for specific networked services and applications. Moreover, any party can take on the role of a network provider by simply offering his virtual network infrastructure to customers, increasing competition in the market. However, the first challenge in realizing a fair and competitive market in a virtual network environment is to have a service negotiation and contracting mechanism in place, that will allow (i) multiple infrastructure providers to participate in a fair and faithful competition, and (ii) a service provider to negotiate the price and quality of service with the providers. In this thesis, we present V-Mart, an open market model and enabling framework for automated service negotiation and contracting in a virtual network environment. To the infrastructure providers, V-Mart fosters an open and fair competition realized by a two stage auction. The V-Mart auction model ensures that bidders (infrastructure providers) bid truthfully, have the flexibility to apply diverse pricing policies, and still gain profit from hosting customers’ virtual resources. To the service providers, V-Mart offers virtual network partitioning algorithms that allow them to divide their virtual networks among competing infrastructure providers while minimizing the total cost. V-Mart offers two types of algorithms to suit different market scenarios. The algorithms not only consider virtual resource hosting price but also the service provider’s preference for resource co-location and the high cost of inter-provider communication. Through extensive simulation experiments we show the efficiency and effectiveness of the algorithms under various market conditions.

The current Internet presents a high barrier to entry for new service providers, due to its inability to accommodate new protocols and technologies, and lack of competition among the network providers. Recently, network virtualization has gained considerable attention as a possible solution, as it enables multiple networks to concurrently run over a shared substrate. It allows for deploying diverse network protocols and technologies customized for specific networked services and applications. Moreover, any party can take on the role of a network provider by simply offering his virtual network infrastructure to customers, increasing competition in the market. However, the first challenge in realizing a fair and competitive market in a virtual network environment is to have a service negotiation and contracting mechanism in place, that will allow (i) multiple infrastructure providers to participate in a fair and faithful competition, and (ii) a service provider to negotiate the price and quality of service with the providers. In this thesis, we present V-Mart, an open market model and enabling framework for automated service negotiation and contracting in a virtual network environment. To the infrastructure providers, V-Mart fosters an open and fair competition realized by a two stage auction. The V-Mart auction model ensures that bidders (infrastructure providers) bid truthfully, have the flexibility to apply diverse pricing policies, and still gain profit from hosting customers’ virtual resources. To the service providers, V-Mart offers virtual network partitioning algorithms that allow them to divide their virtual networks among competing infrastructure providers while minimizing the total cost. V-Mart offers two types of algorithms to suit different market scenarios. The algorithms not only consider virtual resource hosting price but also the service provider’s preference for resource co-location and the high cost of inter-provider communication. Through extensive simulation experiments we show the efficiency and effectiveness of the algorithms under various market conditions.

During the past decade service-orientation has become a popular design paradigm, offering an approach in which services are the functional building blocks. Services are self-contained units of composition, built to be invoked, composed, and destroyed on (user) demand. Service-oriented systems (SOS) are a collection of services that are developed based on several design principles such as: (i) loose coupling between services (e.g., inter-service communication can involve either simple data passing or two or more connected services coordinating some activity) that allows services to be independent, yet highly interoperable when required; (ii) service abstraction, which emphasizes the need to hide as many implementation details as possible, yet still exposing functional and extra-functional capabilities that can be offered to service users; (iii) service reusability provided by the existing services in a rapid and flexible development process; (iv) service composability as one of the main assets of SOS that provide a design platform for services to be composed and decomposed, etc. One of the main concerns in such systems is ensuring service quality per se, but also guaranteeing the quality of newly composed services. To accomplish the above, we consider two system perspectives: the developer's and the user's view, respectively. In the former, one can be assumed to have access to the internal service representation: functionality, enabled actions, resource usage, and interactions with other services. In the second, one has information primarily on the service interface and exposed capabilities (attributes/features). Means of checking that services and service compositions meet the expected requirements, the so-called correctness issue, can enable optimization and possibility to guarantee a satisfactory level of a service composition quality. In order to accomplish exhaustive correctness checks of design-time SOS, we employ model-checking as the main formal verification technique, which eventually provides necessary information about quality-of-service (QoS), already at early stages of system development. ~As opposed to the traditional approach of software system construction, in SOS the same service may be offered at various prices, QoS, and other conditions, depending on the user needs. In such a setting, the interaction between involved parties requires the negotiation of what is possible at request time, aiming at meeting needs on demand. The service negotiation process often proceeds with timing, price, and resource constraints, under which users and providers exchange information on their respective goals, until reaching a consensus. Hence, a mathematically driven technique to analyze a priori various ways to achieve such goals is beneficial for understanding what and how can particular goals be achieved. This thesis presents the research that we have been carrying out over the past few years, which resulted in developing methods and tools for the specification, modeling, and formal analysis of services and service compositions in SOS. The contributions of the thesis consist of: (i)constructs for the formal description of services and service compositions using the resource-aware timed behavioral language called REMES; (ii) deductive and algorithmic approaches for checking correctness of services and service compositions;(iii) a model of service negotiation that includes different negotiation strategies, formally analyzed against timing and resource constraints; (iv) a tool-chain (REMES SOS IDE) that provides an editor and verification support (by integration with the UPPAAL model-checker) to REMES-based service-oriented designs;(v) a relevant case-study by which we exercise the applicability of our framework.The presented work has also been applied on other smaller examples presented in the published papers. / Under det senaste årtiondet har ett tjänstorienterat paradigm blivit allt-mer populärt i utvecklingen av datorsystem. I detta paradigm utgör så kallade tjänster den minsta funktionella systemenheten. Dessa tjänster är konstruerade så att de kan skapas, användas, sammansättas och avslutas separat. De ska vara oberoende av varandra samtidigt som de ska kunna fungera effektivt tillsammans och i samarbete med andra system när så behövs. Vidare ska tjänsterna dölja sina interna implementa-tionsdetaljer i så stor grad som möjligt, samtidigt som deras fulla funktionalitet ska exponeras för systemdesignern. Tjänsterna ska också på ett enkelt sätt kunna återanvändas och sammansättas i en snabb och flexibel utvecklingsprocess.En av de viktigaste aspekterna i tjänsteorienterade datorsystem är att kunna säkerställa systemens kvalitet. För att åstadkomma detta ärdet viktigt att få en djupare insikt om tjänstens interna funktionalitet, i termer av möjliga operationer, resursinformation, samt tänkbar inter-aktion med andra tjänster. Detta är speciellt viktigt när utvecklaren har möjlighet att välja mellan två funktionellt likvärda tjänster somär olika med avseende på andra egenskaper, såsom responstid eller andra resurskrav. I detta sammanhang kan en matematisk beskrivning av en tjänsts beteende ge ökad förståelse av tjänstemodellen, samt hjälpa användaren att koppla ihop tjänster på ett korrekt sätt. En matematisk beskrivning öppnar också upp för ett sätt att matematiskt resonera kring tjänster. Metoder för att kontrollera att komponerade tjänstermöter ställda resurskrav möjliggör också resursoptimering av tjänster samt verifiering av ställda kvalitetskrav.I denna avhandling presenteras forskning som har bedrivits under de senaste åren. Forskningen har resulterat i metoder och verktyg föratt specificera, modellera och formellt analysera tjänster och sammansättning av tjänster. Arbetet i avhandlingen består av (i) en formell definition av tjänster och sammansättning av tjänster med hjälp avett resursmedvetet formellt specifikationsspråk kallat Remes; (ii) två metoder för att analysera tjänster och kontrollera korrektheten i sammansättning av tjänster, både deduktivt och algoritmiskt; (iii) en modell av förhandlingsprocessen vid sammansättning av tjänster som inkluderar olika förhandlingsstrategier; (iv) ett antal verktyg som stödjer dessa metoder. Metoderna har använts i ett antal fallstudier som är presenterade i de publicerade artiklarna. / Contesse

Background. Despite the prevalence of sex work and strip clubs across Canadian urban geographies, few studies explore the occupational health and safety outcomes related to indoor male sex work, let alone male stripping whereby men dance for men. Moreover, the sexual service negotiation process in the sex work industry remains to be explored. In knowing that sexual practices with high HIV/STI rates occur in strip clubs (e.g., condomless oral, vaginal, and anal sex), as well as widespread psychoactive substance use among strippers, the purpose of this study was to explore the cultural features of male strippers’ work that impact their health and safety outcomes. Methodology. For this study, we recruited 14 male strippers working with male clients in a Canadian city. Critical ethnography was our espoused methodology. Through field observations, informal conversations, questionnaires, and semi-structured qualitative interviews, we explored the process of sexual transactions between strippers and clients. We used a postmodern angle to interpret our findings through the works of Deleuze, Guattari, and Foucault. Findings. The male strip club is a social matrix produced by the intersection of motivational forces: the motivation to gain money, pleasure, or intimacy, and the motivation to abide by socio-cultural and legal norms. It is upon a matrix of financial necessity and socio-cultural and legal constraints that sex work transactions unfold in the club. Moreover, the club’s health and safety conditions and strippers’ transaction outcomes result from intersecting motivations. Finally, sexual service negotiation is a process of configuring motivational forces between social agents. The motivation for financial gain revealed itself to be the strongest and most consistent force; the focus on capital gain generated asymmetrical connections between strippers, clients, and business entrepreneurs, resulting in specific health and safety outcomes. Conclusion. The Canadian legal and political context surrounding male sex work negatively impacts male strippers’ occupational health and safety conditions by disabling safe connections with clients. Further, the emphasis on money-making activities encourages strippers to value financial gain over their physical and mental integrity. In short, the male strip club work environment is configured in a manner whereby capital gain is prioritized and strippers’ health and safety is undermined.