Electronic Communications of the EASST (European Association of Software Science and Technology)
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A practical approach to multi-modeling views composition
Get PDFThe use of several view models to specify a complex system is a common practice to provide the most appropriate abstractions to model its diverse concerns. When several view models are used to specify a system, it is necessary to compose them to generate the application. When the view models are expressed in different Domain Specific Modeling Languages a problem arises because a heterogeneous composition is required. A possible approach to avoid a heterogeneous composition is to transform the diverse models into low-level models using a common low-level modeling language as target. Therefore, when all the view models are transformed in low-level models specified with a common language, it is possible to apply a ho- mogeneous composition to obtain the final application. However, it is necessary to identify the elements to compose in the low-level. In this paper, we present an auto- matic mechanism to identify which elements will be composed. This mechanism is based on defining correspondence relationships between the high-level view mod- els and automatically deriving new correspondence between the generated low-level models
Deriving Barbed Bisimulations for Bigraphical Reactive Systems
Get PDFWe study the definition of a general abstract notion of barbed bisimilarity for reactive systems on bigraphs. More precisely, given a bigraphical reactive system, we define the corresponding barbs from the contextual labels given by the IPO construction, in a general and systematic way. These barbs correspond to observe which names on the interface are actually involved in reactions (and how).
As examples, we apply this construction to the (bigraphical representation of the) pi-calculus and of Mobile Ambients, and compare the resulting barbed equivalences with those previously known for these calculi
Towards SMV Model Checking of Signal (multi-clocked) Specifications
Get PDFSignal is a high-level data-flow specification language that equally
allows multi-clocked descriptions as well as single-clocked ones.
It has a formal semantics and is supported by several formal tools for
simulation and static validation.
This generality renders it useful for various specification, simulation, and
verification tasks in embedded system design.
SMV, in turn, is a language and model checker where synchronous models are single-clocked by definition.
Roughly, we use standard techniques to describe clocks by Boolean variables, with the advantage that the number of such variables is kept to a minimum through a static analysis provided by the Signal compiler.
In particular, we propose a translation from possibly multi-clocked
Signal specifications into SMV specifications for their corresponding verification by model checking
Kontextsensitive Konfiguration und Ausführung verteilter Geschäftsprozesse
Get PDFZusammenfassung:
In der Entwicklung moderner Informationssysteme gibt es einen Trend in Richtung adaptiver
Systeme. Mittlerweile existieren diverse Ansätze auf dem Gebiet der Umgebungsintelligenz
(Ambient Intelligence), in denen sich eine intelligente Umgebung an ihren Benutzer anpasst.
Aktuelle Forschungsansätze untersuchen in diesem Zusammenhang auch Adaptivität in den
Bereichen Geschäftsprozess- und Dienstleistungsmanagement. Ein Umsetzungskonzept für
Adaptivität ist Kontextsensitivität. In diesem Beitrag wird ein holistischer Ansatz für die kontextsensitive
Konfiguration und Ausführung von Dienstleistungen und der ihnen zugrundeliegenden
Geschäftsprozesse beschrieben, der im Rahmen des vom Bundesministerium für
Wirtschaft und Technologie (BMWi) geförderten Forschungsprojekts Robot to Business entwickelt
wird. Die Integration von Kontext wird dabei auf drei unterschiedlichen Ebenen berücksichtigt
(Dienstleistungen, Geschäftsprozesse, Technologie). Der Ansatz wird innerhalb
des Projekts in zwei unterschiedlichen Anwendungsgebieten evaluiert (Landwirtschaft und IT
Service Management), um sowohl die kontextsensitive Rekombinierbarkeit und Konfiguration
von Leistungsmodulen (build time) als auch die kontextsensitive Ausnahmebehandlung in den
zugehörigen Geschäftsprozessen (run time) nachzuweisen
VOLARE: Adaptive Web Service Discovery Middleware for Mobile Systems
Get PDFWith the recent advent and widespread use of smart mobile devices, the flexibility and versatility offered by Service Oriented Architecture's (SOA) makes it an ideal approach to use in the rapidly changing mobile environment. However, the mobile
setting presents a set of new challenges that service discovery methods developed for nonmobile environments cannot address. The requirements a mobile client device will have
from a Web service may change due to changes in the context or the resources of the client device. In a similar manner, a mobile device that acts as a Web service provider will
have different capabilities depending on its status, which may also change dramatically during runtime. This paper introduces VOLARE, a middleware-based solution that will monitor the resources and context of the device, and adapt service requests accordingly. The same method will be used to adapt the Quality of Service (QoS) levels advertised by service providers, to realistically reflect each provider's capabilities at any given moment. This approach will allow for more resource-efficient and accurate service discovery in mobile systems and will enable more reliable provider functionality in mobile devices
Towards an Interest Management Scheme for Peer-based Virtual Environments
Get PDFA fundamental task in peer-to-peer-based Massively Multiuser Virtual Environments is providing all peers with a consistent view of the environment. To do so, state changes must be propagated to peers. To limit the resulting network traffic,
existing approaches often restrict the distribution of a state change to peers for which it is relevant. The identification of such peers is known as Interest Management. Typically Interest Management is done based on so-called Areas of Interest. An
Area of Interest is a spatial area around a user's avatar. If a change occurs inside this area, it is relevant and must be reported to the corresponding peer. We propose
to extend this approach with so-called Areas of Effect. An Area of Effect specifies the spatial area of the virtual environment that is directly influenced by a given state change. A state change is propagated to all peers whose Areas of Interest intersect with the change's Area of Effect. This allows us to model complex state changes with arbitrary and possibly dynamic influence areas. They may even affect multiple
areas at once. In this paper we describe our approach and give an overview on the current state of it's implementation
Network Virtualization: Implementation Steps Towards the Future Internet
Get PDFIn this paper we will investigate why and how Network Virtualization
(NV) can overcome the shortfalls of the current system and how it paves the way for the Future Internet. Therefore, we will first discuss some major deficiencies and achievements of today's Internet. Afterwards, we identify three major building blocks of NV: a) the use of application-specific routing overlays, b) the safe consolidation
of resources by OS virtualization on a generic infrastructure, and c) the
exploitation of the network diversity for performance enhancements and for new business models, such as the provisioning of intermediate nodes or path oracles. Subsequently, we discuss an implementation scheme for network virtualization or routing overlays based on one-hop source routers (OSRs). The capabilities of the combination of NV and OSRs are demonstrated by a concurrent multipath transmission
(CMP) mechanism (also known as stripping) for obtaining high throughput transmission pipes. The suggested stripping mechanism constitutes a first instance of a refinement of the concept of NV, the idea of transport system virtualization
Resource-based enactment and adaptation of workflows from activity diagrams
Get PDFWorkflow management deals with different types of dependencies among tasks, in particular data- and policy-driven. The ability to reason on dependencies of different type allows workflow designers to consider different alternatives, or to define customized flows, reducing non-determinism. We propose a resource-centered view, in which both data-dependency between tasks and plan-dependent ordering of tasks are expressed as production and consumption of resources. This view is translated into a rule-based formalism, expressed in terms of multi-set rewriting for workflow enactment.
In turn, rules are themselves seen as resources, so that they are prone to the same rewriting process, in order to redefine process schemas. We show how workflows expressed as activity diagrams can be translated to the proposed formalism, exploiting enforced generative patterns applied to triple graph grammars, and how redefinition of workflow processes can occur through typical patterns of adaptation. We also discuss possible concrete syntaxes for the obtained rules
Context-Aware Service Selection with Uncertain Context Information
Get PDFThe current evolution of Service-Oriented Computing in ubiquitous systems
is leading to the development of context-aware services. These are services
whose description is enriched with context information related to the service execution
environment and adaptation capabilities. This information is often used for discovery
and adaptation purposes. However, in real-life systems context information
is naturally dynamic, uncertain and incomplete, which represents an important issue
when comparing service description and user requirements. Uncertainty of context
information may lead to an inexact match between provided and required service
capabilities, and consequently to the non-selection of services. In order to handle
uncertain and incomplete context information, we propose a mechanism inspired
by graph-comparison for matching contextual service descriptions using similarity
measures that allow inexact matching. Service description and requirements are
compared using two kinds of similarity measures: local measures, which compare
individually required and provided properties, and global measures, which take into
account the context description as a whole. We show how the proposed mechanism
is integrated in MUSIC, an existing adaptation middleware, and how it enables more
optimal adaptation decision making