1,594 research outputs found
SLAng: A language for defining service level agreements
Application or web services are increasingly being used across organisational boundaries. Moreover, new services are being introduced at the network and storage level. Languages to specify interfaces for such services have been researched and transferred into industrial practice. We investigate end-to-end quality of service (QoS) and highlight that QoS provision has multiple facets and requires complex agreements between network services, storage services and middleware services. We introduce SLAng, a language for defining Service Level Agreements (SLAs) that accommodates these needs. We illustrate how SLAng is used to specify QoS in a case study that uses a web services specification to support the processing of images across multiple domains and we evaluate our language based on it
Precise service level agreements
SLAng is an XML language for defining service level agreements, the part of a contract between the client and provider of an Internet service that describes the quality attributes that the service is required to possess. We define the semantics of SLAng precisely by modelling the syntax of the language in UML, then embedding the language model in an environmental model that describes the structure and behaviour of services. The presence of SLAng elements imposes behavioural constraints on service elements, and the precise definition of these constraints using OCL constitutes the semantic description of the language. We use the semantics to define a notion of SLA compatibility, and an extension to UML that enables the modelling of service situations as a precursor to analysis, implementation and provisioning activities
Heterogeneous component interactions: Sensors integration into multimedia applications
Resource-constrained embedded and mobile devices are becoming increasingly
common. Since few years, some mobile and ubiquitous devices such as wireless
sensor, able to be aware of their physical environment, appeared. Such devices
enable proposing applications which adapt to user's need according the context
evolution. It implies the collaboration of sensors and software components
which differ on their nature and their communication mechanisms. This paper
proposes a unified component model in order to easily design applications based
on software components and sensors without taking care of their nature. Then it
presents a state of the art of communication problems linked to heterogeneous
components and proposes an interaction mechanism which ensures information
exchanges between wireless sensors and software components
Sustaining a Vertically Disintegrated Network through a Bearer Service Market
Based upon the Internet perspective, this chapter will attempt to clarify and revise
several ideas about the separation between infrastructure facilities and service
offerings in digital communications networks. The key notions that we will focus on
in this paper are: i) the bearer service as a technology-independent interface which
exports blind network functionality to applications development; ii) the sustainability
of an independent market for bearer service and the organizational consequences
associated with such a market
Open Layered Networks: the Growing Importance of Market Coordination
Based upon the Internet perspective, this paper will attempt to clarify and revise
several ideas about the separation between infrastructure facilities and service
offerings in digital communications networks. The key notions that we will focus on in
this paper are: i) the bearer service as a technology-independent interface which
exports blind network functionality to applications development; ii) the organizational
consequences associated with the emergence of a sustainable market of bearer service:
a clear movement at the level of industrial structure from traditional hierarchies to
more market coordination
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