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Finding secure compositions of software services: Towards a pattern based approach
In service based systems, there is often a need to replace services at runtime as they become either unavailable or they no longer meet required quality or security properties. In such cases, it is often necessary to build compositions of services that can replace a problematic service because no single service with a sufficient match to it can be located. In this paper, we present an approach for building compositions of services that can preserve required security properties. Our approach is based on the use of secure composition patterns which are applied in connection with basic discovery mechanisms to build secure service compositions
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Constructing secure service compositions with patterns
In service based applications, it is often necessary to construct compositions of services in order to provide required functionality in cases where this is not possible through the use of a single service. Whilst creating service compositions, it is necessary to ensure not only that the functionality required of the composition is achieved but also that certain security properties are preserved. In this paper, we describe an approach to constructing secure service compositions. Our approach is based on the use of composition patterns and rules that determine the security properties that should be preserved by the individual services that constitute a composition in order to ensure that security properties of the overall composition are also satisfied. Our approach extends a framework developed to support the runtime service discovery
Multifractal metal in a disordered Josephson Junction Array
We report the results of the numerical study of the non-dissipative quantum
Josephson junction chain with the focus on the statistics of many-body wave
functions and local energy spectra. The disorder in this chain is due to the
random offset charges. This chain is one of the simplest physical systems to
study many-body localization. We show that the system may exhibit three
distinct regimes: insulating, characterized by the full localization of
many-body wavefunctions, fully delocalized (metallic) one characterized by the
wavefunctions that take all the available phase volume and the intermediate
regime in which the volume taken by the wavefunction scales as a non-trivial
power of the full Hilbert space volume. In the intermediate, non-ergodic regime
the Thouless conductance (generalized to many-body problem) does not change as
a function of the chain length indicating a failure of the conventional
single-parameter scaling theory of localization transition. The local spectra
in this regime display the fractal structure in the energy space which is
related with the fractal structure of wave functions in the Hilbert space. A
simple theory of fractality of local spectra is proposed and a new scaling
relationship between fractal dimensions in the Hilbert and energy space is
suggested and numerically tested.Comment: 11 page
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