Enterprises apply SOAs to implement business processes as services which are adaptive to software changes and updates. Service management has to ensure high availability, performance and fault tolerance and is therefo...
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Enterprises apply SOAs to implement business processes as services which are adaptive to software changes and updates. Service management has to ensure high availability, performance and fault tolerance and is therefore crucial for the undisturbed functionality of a SOA. However, manual service management is cumbersome with a large amount of services and applications. Services that fail or do not achieve a certain quality of service (QoS) need to be manually replaced. Up to now, a fully automatic approach is missing. We introduce a semantic model and architecture for automatic service brokering in service-oriented architectures (SOA). A Service Broker is used for semantic service discovery with respect to functional criteria and QoS. Hence, we use a semantic matching algorithm on an extension of the OWL-S ontology. Services are requested by service containers which monitor and replace services in interaction withthe service broker. the architecture is presented with an implementation using Web Services.
As e-businesses are becoming ubiquitous, enhancing the performance and scalability of e-business systems has become an increasingly important topic of investigation. As Vitruvius (70-25 BC) put it succinctly 'func...
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As e-businesses are becoming ubiquitous, enhancing the performance and scalability of e-business systems has become an increasingly important topic of investigation. As Vitruvius (70-25 BC) put it succinctly 'function follows form', the ability of a system to perform well and scale easily is influenced by how the system itself is formed or implemented. A common approach to implement e-business systems is to make use of off-the-shelf enterprise middleware systems, such as a J2EE-compliant application server. Such middleware systems handle several, often complex, issues and thus simplify application development. they however allow developers the freedom not to use particular forms of support they offer and build their own mechanisms instead. this flexibility gives rise to many implementation methods. the work reported here evaluates these methods for Response Time and throughput under various environments related to both client side (external to the system) and application execution (internal). To this end, one of the most widespread technologies used by the industry, the Enterprise Java Beans (EJB), is chosen; we have considered six commonly used implementation methods for an e-auction application and five different client-side and execution environments. the resulting study, which involves 78 experimental runs, identifies the strengths and the weaknesses of each implementation method under 13 different scenarios. It thus offers reliable guidelines for developers and valuable insights to researchers.
Rule-based systems are a promising means to specify interface standards for artificial intelligence tools and modules for games, as advocated by the international Came Developers Association. Rules, however, can be to...
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ISBN:
(纸本)3540454624
Rule-based systems are a promising means to specify interface standards for artificial intelligence tools and modules for games, as advocated by the international Came Developers Association. Rules, however, can be too flexible, allowing undisciplined and "dirty" programming styles and solutions. We advocate in this paper that although rules are a good starting point towards standardising artificial intelligence techniques in games, they must be complemented with automatically verifiable rule schemata to ensure the appropriate implementation of such techniques and theories. We illustrate our point with a specific rule-based implementation of a theory of norms for synthetic characters which enables the specification of sophisticated behaviours.
We describe the design and implementation of a trust-management system Soutei, a dialect of Binder, for access control in distributed systems. Soutei policies and credentials are written in a declarative logic-based s...
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this paper proposes a flexible transactional behavior model for services coordination. We assume that given a flow describing the application logic of a service based application, it is possible to associate to it a p...
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this paper proposes a flexible transactional behavior model for services coordination. We assume that given a flow describing the application logic of a service based application, it is possible to associate to it a personalised transactional behaviour in an orthogonal way. this behaviour is defined by specifying contracts and associating a well defined behaviour to the activities participating in the coordination. Such contracts ensure transactional properties at execution time in the presence of exceptions
We design and implement a library for adding backtracking computations to any Haskell monad. Inspired by logicprogramming, our library provides, in addition to the operations required by the MonadPlus interface, cons...
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We design and implement a library for adding backtracking computations to any Haskell monad. Inspired by logicprogramming, our library provides, in addition to the operations required by the MonadPlus interface, constructs for fair disjunctions, fair conjunctions, conditionals, pruning, and an expressive top-level interface. Implementing these additional constructs is easy in models of backtracking based on streams, but not known to be possible in continuation-based models. We show that all these additional constructs can be generically and monadically realized using a single primitive msplit. We present two implementations of the library: one using success and failure continuations;and the other using control operators for manipulating delimited continuations.
We present a compositional program logic for call-by-value imperative higher-order functions with general forms of aliasing, which can arise from the use of reference names as function parameters, return values, conte...
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We present a compositional program logic for call-by-value imperative higher-order functions with general forms of aliasing, which can arise from the use of reference names as function parameters, return values, content of references and parts of data structures. the program logic extends our earlier logic for alias-free imperative higher-order functions with new modal operators which serve as building blocks for clean structural reasoning about programs and data structures in the presence of aliasing. this has been an open issue since the pioneering work by Cartwright-Oppen and Morris twenty-five years ago. We illustrate usage of the logic for description and reasoning through concrete examples including a higher-order polymorphic Quicksort. the logical status of the new operators is clarified by translating them into (in)equalities of reference names. the logic is observationally complete in the sense that two programs are observationally indistinguishable iff they satisfy the same set of assertions.
We describe a monadic interface to low-level hardware features that is a suitable basis for building operating systems in Haskell. the interface includes primitives for controlling memory management hardware, user-mod...
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We describe a monadic interface to low-level hardware features that is a suitable basis for building operating systems in Haskell. the interface includes primitives for controlling memory management hardware, user-mode process execution, and low-level device I/O. the interface enforces memory safety in nearly all circumstances. Its behavior is specified in part by formal assertions written in a programminglogic called P-logic. the interface has been implemented on bare IA32 hardware using the Glasgow Haskell Compiler (GHC) runtime system. We show how a variety of simple O/S kernels can be constructed on top of the interface, including a simple separation kernel and a demonstration system in which the kernel, window system, and all device drivers are written in Haskell.
We design and implement a library for adding backtracking computations to any Haskell monad. Inspired by logicprogramming, our library provides, in addition to the operations required by the MonadPlus interface, cons...
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Defeasible reasoning is a rule-based approach for efficient reasoning with incomplete and inconsistent information. Such reasoning is, among others, useful for ontology integration, where conflicting information arise...
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Defeasible reasoning is a rule-based approach for efficient reasoning with incomplete and inconsistent information. Such reasoning is, among others, useful for ontology integration, where conflicting information arises naturally;and for the modeling of business rules and policies, where rules with exceptions are often used. this paper describes these scenarios in more detail, and reports on the implementation of a system for defeasible reasoning on the Web. the system (a) is syntactically compatible with RuleML;(b) features strict and defeasible rules, priorities and two kinds of negation;(c) is based on a translation to logicprogramming with declarative semantics;(d) is flexible and adaptable to different intuitions within defeasible reasoning;and (e) can reason with rules, RDF, RDF Schema and (parts of) OWL ontologies.
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