The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Steven Derrien - One of the best experts on this subject based on the ideXlab platform.
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using model types to Support Contract aware model substitutability
European Conference on Modelling Foundations and Applications, 2013Co-Authors: Benoit Combemale, Steven DerrienAbstract:Model typing extends the applicability of typing to model-oriented type system by assigning models with specific types. It provides Support for model substitutability addressing a wide range of facilities such as model transformation reuse. While existing approaches are limited to object-oriented metamodels (e.g., MOF) as types, there is a need for exploring more precise types. In particular, we propose in this paper an extension to model typing that takes into account Contract-aware substitutability where Contracts are defined in terms of invariants and pre-/postconditions expressed using OCL. While invariants offer a suitable way to complete object-oriented metamodels with additional structural properties, pre-/postconditions pave the way of behavioral substitutability for model transformation specialization. We also provide an implementation to rigorously reason about the substitutability on model types with Contracts and apply it on use cases coming from the optimizing compiler community.
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ECMFA - Using model types to Support Contract-aware model substitutability
Modelling Foundations and Applications, 2013Co-Authors: Benoit Combemale, Steven DerrienAbstract:Model typing extends the applicability of typing to model-oriented type system by assigning models with specific types. It provides Support for model substitutability addressing a wide range of facilities such as model transformation reuse. While existing approaches are limited to object-oriented metamodels (e.g., MOF) as types, there is a need for exploring more precise types. In particular, we propose in this paper an extension to model typing that takes into account Contract-aware substitutability where Contracts are defined in terms of invariants and pre-/postconditions expressed using OCL. While invariants offer a suitable way to complete object-oriented metamodels with additional structural properties, pre-/postconditions pave the way of behavioral substitutability for model transformation specialization. We also provide an implementation to rigorously reason about the substitutability on model types with Contracts and apply it on use cases coming from the optimizing compiler community.
Benoit Combemale - One of the best experts on this subject based on the ideXlab platform.
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using model types to Support Contract aware model substitutability
European Conference on Modelling Foundations and Applications, 2013Co-Authors: Benoit Combemale, Steven DerrienAbstract:Model typing extends the applicability of typing to model-oriented type system by assigning models with specific types. It provides Support for model substitutability addressing a wide range of facilities such as model transformation reuse. While existing approaches are limited to object-oriented metamodels (e.g., MOF) as types, there is a need for exploring more precise types. In particular, we propose in this paper an extension to model typing that takes into account Contract-aware substitutability where Contracts are defined in terms of invariants and pre-/postconditions expressed using OCL. While invariants offer a suitable way to complete object-oriented metamodels with additional structural properties, pre-/postconditions pave the way of behavioral substitutability for model transformation specialization. We also provide an implementation to rigorously reason about the substitutability on model types with Contracts and apply it on use cases coming from the optimizing compiler community.
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ECMFA - Using model types to Support Contract-aware model substitutability
Modelling Foundations and Applications, 2013Co-Authors: Benoit Combemale, Steven DerrienAbstract:Model typing extends the applicability of typing to model-oriented type system by assigning models with specific types. It provides Support for model substitutability addressing a wide range of facilities such as model transformation reuse. While existing approaches are limited to object-oriented metamodels (e.g., MOF) as types, there is a need for exploring more precise types. In particular, we propose in this paper an extension to model typing that takes into account Contract-aware substitutability where Contracts are defined in terms of invariants and pre-/postconditions expressed using OCL. While invariants offer a suitable way to complete object-oriented metamodels with additional structural properties, pre-/postconditions pave the way of behavioral substitutability for model transformation specialization. We also provide an implementation to rigorously reason about the substitutability on model types with Contracts and apply it on use cases coming from the optimizing compiler community.
Mario Alessandro Bochicchio - One of the best experts on this subject based on the ideXlab platform.
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Service and Contract composition: A model and a tool
2015 IFIP IEEE International Symposium on Integrated Network Management (IM), 2015Co-Authors: Antonella Longo, Marco Zappatore, Mario Alessandro BochicchioAbstract:Cloud computing services are seeing great success in IT scenarios. Dynamic reservation and allocation of network, storage and computational resources, the hiding of visibility of internal IT components, as well as the pay-per-use paradigm are nowadays more and more widespread ways to provide and consume services. Their complexity, however, is clearly visible in composing services to satisfy users' requests, as well as in performance monitoring and service level comparisons. Effective ways are then needed to model both Contracts and Service Level Agreements (SLAs) referring to the services that have to be provided to customers. However, this is hindered by a lack of expressivity in current SLA specifications and a consequent inadequacy in tools for managing SLAs and Contract composition aspects. Therefore, we present a possible extension of WSLA, a widely known SLA description language, for modeling Contracts and SLAs suitable to Support Contract owners during service composition and monitoring phases. An ad-hoc developed tool based on tree-graphs is examined to assess the feasibility of the proposed model and to simplify SLA and Contract composition.
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Service Level Aware - Contract Management
2015 IEEE International Conference on Services Computing, 2015Co-Authors: Antonella Longo, Marco Zappatore, Mario Alessandro BochicchioAbstract:The success achieved by Cloud Computing Services (CCSs) in modern IT scenarios is nowadays a matter of fact and service offerings between providers and customers continuously grow up and widen their scope. Similarly, service offerings are more and more based upon dynamic reservation and allocation of network, storage and computational resources, the hiding of visibility of internal IT components, as well as the pay-per-use paradigm. The main drawback of such a situation is represented by the complexity in composing services to satisfy users' requests, as well as in performance monitoring and service level comparisons. Effective strategies are then needed to model IT service Contracts and corresponding Service Level Agreements (SLAs), as well as their composition. However, the lack of expressivity in current SLA specifications and the inadequacy of tools for managing SLA and Contract compositions is relevant. Therefore, we present a possible extension of WSLA, a widely known SLA description language, for modeling Contracts and SLAs suitable to Support Contract owners during service composition and monitoring phases. An ad-hoc developed tool based on the usage of directed tree-graphs and of a rule-based engine is examined to assess the feasibility of the proposed model and to simplify SLA and Contract composition.
Karen Northon - One of the best experts on this subject based on the ideXlab platform.
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NASA Awards Launch Services Program Support Contract
2020Co-Authors: Karen NorthonAbstract:NASA has awarded a Contract to a.i. solutions, Inc., of Lanham, Maryland, to Support the agency’s Launch Services Program (LSP) in providing end-to-end launch services for NASA and NASA-sponsored payloads on commercial expendable launch vehicles.
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NASA Awards Engineering, Research Support Contract
2020Co-Authors: Karen NorthonAbstract:NASA has selected HX5, LLC of Fort Walton Beach, Florida, to perform engineering, research and scientific Support at NASA’s Glenn Research Center in Cleveland.
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nasa awards facility operations Support Contract
2018Co-Authors: Karen NorthonAbstract:NASA has awarded a Contract to COLSA Corporation of Huntsville, Alabama, to provide facility operations Support services to the National Center for Critical Information Processing and Storage (NCCIPS).
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nasa extends chandra operations science Support Contract
2018Co-Authors: Karen NorthonAbstract:NASA has awarded a Contract extension to the Smithsonian Astrophysical Observatory (SAO) in Cambridge, Massachusetts, to continue operations and science Support for the agency's Chandra X-ray Observatory.
Simon Brocklebank - One of the best experts on this subject based on the ideXlab platform.
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perspectives on trading cost and availability for corrective maintenance at the equipment type level
Reliability Engineering & System Safety, 2017Co-Authors: John Ahmet Erkoyuncu, Alexandre Lopez Eiroa, Nigel Butler, Keith R Rushton, Samir Khan, Simon BrocklebankAbstract:Characterising maintenance costs has always been challenging due to a lack of accurate prior cost data and the uncertainties around equipment usage and reliability. Since preventive maintenance does not completely prevent corrective repairs in demanding environments, any unscheduled maintenance can have a large impact on the overall maintenance costs. This introduces the requirement to set up Support Contracts with minimum baseline solutions that warrant the target demand within certain costs and risks. This article investigates a process that has been developed to estimate performance based Support Contract costs attributed to corrective maintenance. These can play a dominant role in the through-life Support of high values assets. The case context for the paper is the UK Ministry of Defence. The developed approach allows benchmarking Support Contract solutions, and enabling efficient planning decisions. Emphasis is placed on learning from feedback, testing and validating current methodologies for estimating corrective maintenance costs and availability at the Equipment Type level. These are interacting sub-equipment's that have unique availability requirements and hence have a much larger impact on the capital maintenance expenditure. The presented case studies demonstrate the applicability of the approach towards adequate savings and improved availability estimates.
