7,416 research outputs found
Web Services: A Process Algebra Approach
It is now well-admitted that formal methods are helpful for many issues
raised in the Web service area. In this paper we present a framework for the
design and verification of WSs using process algebras and their tools. We
define a two-way mapping between abstract specifications written using these
calculi and executable Web services written in BPEL4WS. Several choices are
available: design and correct errors in BPEL4WS, using process algebra
verification tools, or design and correct in process algebra and automatically
obtaining the corresponding BPEL4WS code. The approaches can be combined.
Process algebra are not useful only for temporal logic verification: we remark
the use of simulation/bisimulation both for verification and for the
hierarchical refinement design method. It is worth noting that our approach
allows the use of any process algebra depending on the needs of the user at
different levels (expressiveness, existence of reasoning tools, user
expertise)
Web services synchronization health care application
With the advance of Web Services technologies and the emergence of Web
Services into the information space, tremendous opportunities for empowering
users and organizations appear in various application domains including
electronic commerce, travel, intelligence information gathering and analysis,
health care, digital government, etc. In fact, Web services appear to be s
solution for integrating distributed, autonomous and heterogeneous information
sources. However, as Web services evolve in a dynamic environment which is the
Internet many changes can occur and affect them. A Web service is affected when
one or more of its associated information sources is affected by schema
changes. Changes can alter the information sources contents but also their
schemas which may render Web services partially or totally undefined. In this
paper, we propose a solution for integrating information sources into Web
services. Then we tackle the Web service synchronization problem by
substituting the affected information sources. Our work is illustrated with a
healthcare case study.Comment: 18 pages, 12 figure
An Optimal Trade-off between Content Freshness and Refresh Cost
Caching is an effective mechanism for reducing bandwidth usage and
alleviating server load. However, the use of caching entails a compromise
between content freshness and refresh cost. An excessive refresh allows a high
degree of content freshness at a greater cost of system resource. Conversely, a
deficient refresh inhibits content freshness but saves the cost of resource
usages. To address the freshness-cost problem, we formulate the refresh
scheduling problem with a generic cost model and use this cost model to
determine an optimal refresh frequency that gives the best tradeoff between
refresh cost and content freshness. We prove the existence and uniqueness of an
optimal refresh frequency under the assumptions that the arrival of content
update is Poisson and the age-related cost monotonically increases with
decreasing freshness. In addition, we provide an analytic comparison of system
performance under fixed refresh scheduling and random refresh scheduling,
showing that with the same average refresh frequency two refresh schedulings
are mathematically equivalent in terms of the long-run average cost
Toward a Formal Semantics for Autonomic Components
Autonomic management can improve the QoS provided by parallel/ distributed
applications. Within the CoreGRID Component Model, the autonomic management is
tailored to the automatic - monitoring-driven - alteration of the component
assembly and, therefore, is defined as the effect of (distributed) management
code. This work yields a semantics based on hypergraph rewriting suitable to
model the dynamic evolution and non-functional aspects of Service Oriented
Architectures and component-based autonomic applications. In this regard, our
main goal is to provide a formal description of adaptation operations that are
typically only informally specified. We contend that our approach makes easier
to raise the level of abstraction of management code in autonomic and adaptive
applications.Comment: 11 pages + cover pag
Components Interoperability through Mediating Connector Patterns
A key objective for ubiquitous environments is to enable system
interoperability between system's components that are highly heterogeneous. In
particular, the challenge is to embed in the system architecture the necessary
support to cope with behavioral diversity in order to allow components to
coordinate and communicate. The continuously evolving environment further asks
for an automated and on-the-fly approach. In this paper we present the design
building blocks for the dynamic and on-the-fly interoperability between
heterogeneous components. Specifically, we describe an Architectural Pattern
called Mediating Connector, that is the key enabler for communication. In
addition, we present a set of Basic Mediator Patterns, that describe the basic
mismatches which can occur when components try to interact, and their
corresponding solutions.Comment: In Proceedings WCSI 2010, arXiv:1010.233
Semantic annotation of Web APIs with SWEET
Recently technology developments in the area of services on the Web are marked by the proliferation of Web applications and APIs. The development and evolution of applications based on Web APIs is, however, hampered by the lack of automation that can be achieved with current technologies. In this paper we present SWEET - Semantic Web sErvices Editing Tool - a lightweight Web application for creating semantic descriptions of Web APIs. SWEET directly supports the creation of mashups by enabling the semantic annotation of Web APIs, thus contributing to the automation of the discovery, composition and invocation service tasks. Furthermore, it enables the development of composite SWS based applications on top of Linked Data
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