Abstract.In this paper, we analyze overload control for composite web services in service oriented architectures by an orchestrating broker, and propose two practical access control rules which effectively mitigate the effects of severe overloads at some web services in the composite service. These two rules aim to keep overall web service performance (in terms of end-to-end response time) and availability at agreed quality of service levels. We present the theoretical background and design of these access control rules as well as performance evaluation results obtained by both simulation and experiments. We show that our access control rules significantly improve performance and availability of composite web services.

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There are numerous methods to measure the impact of ICT on the environment, all of them different in scope, some of them incomplete and it is difficult to see the connection between them. This study draws an inventory of methods to assess the impact of ICT which all of them have their pros and cons. Furthermore, this study defines the building blocks a more complete method to evaluate both the positive and negative impacts of ICT on People, Planet and Profit.