Service-Oriented Architecture (SOA) provides a flexible framework for service composition. Using standard-based protocols (such as SOAP and WSDL), composite services can be constructed by integrating atomic services developed independently. Algorithms are needed to select service components with various QoS levels according to some application-dependent performance requirements. We design a broker-based architecture to facilitate the selection of QoS-based services. The objective of service selection is to maximize an application-specific utility function under the end-to-end QoS constraints. The problem is modeled in two ways: the combinatorial model and the graph model. The combinatorial model defines the problem as a multidimension multichoice 0-1 knapsack problem (MMKP). The graph model defines the problem as a multiconstraint optimal path (MCOP) problem. Efficient heuristic algorithms for service processes of different composition structures are presented in this article and their performances are studied by simulations. We also compare the pros and cons between the two models.

BackgroundChina had proposed the unification of equity and efficiency since the launch of the new round of health system reform in 2009. And the central government gave priority to the development of primary health care (PHC) whilst ensuring its availability and improving its efficiency. This study aimed to evaluate the changes of equity and efficiency in PHC resource allocation (PHCRA) and explored ways to improve the current situation.MethodsThe data of this study came from the China Health Statistical Yearbook (2013–2017) and China Statistical Yearbook (2017). Three and five indicators were used to measure equity and efficiency, respectively. The Lorenz curve, Gini coefficient (G), Theil index (T) and health resource density index (HRDI) were used to assess equity in demographic and geographical dimensions. Data envelopment analysis (DEA) and the Malmquist productivity index (MPI) were chosen to measure the efficiency and productivity of PHCRA.ResultsFrom 2012 to 2016, the total amount of PHCR had increased year by year. The Gs by population size were below 0.2 and that by geographical area were between 0.6 and 0.7. T had the same trend with G, and intra-regional contribution rates were higher than inter-regional contribution rates, which were all beyond 60%. From 2012 to 2016, the numbers of provinces that achieved an effective DEA were 4, 3, 4, 5 and 5, respectively. The mean of the total factor productivity index was 0.994.ConclusionThe equity of PHCRA in terms of population size is superior in the geographical area. Intra-regional differences are the main source of inequality. The eastern region has the highest density of PHCR, whereas the western region has the lowest. In addition, PHC institutions in more than 80% of the provinces are inefficient, and the productivity of the institutions decline by 0.6% from 2012 to 2016 because of technological retrogression.

Service-oriented architecture (SOA) provides a powerful paradigm to compose service processes using individual atomic services. When running a service process, SOA needs an efficient and effective mechanism to detect service delivery failures and to identify the individual service(s) that causes the problem. In this research, we study the model of accountability to detect, diagnose, and defuse the real cause of a problem when service errors (such as incorrect result or SLA violation) occur in a service process. Our approach leverages Bayesian networks to identify the most likely problematic services in a process and selectively inspect those services. An evidence channel selection algorithm is designed to specify which services in a service network should be monitored to achieve the best cost-efficiency. We model the channels selection as the classic facilities location problem. We also adopt a continuous knowledge learning process to manage the dynamic nature of SOA. The performance study shows that our proposed accountability mechanism is effective on identifying the root cause of problems and can achieve significant cost savings: with 50% of services' outputs monitored as evidence, the comprehensive diagnosis correctness can reach 80% after only 20% of services are inspected.

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