A ubiquitous Knowledge Base (u-KB) is a distributed and decentralized knowledge base where the factual knowledge (i.e. individuals) is scattered among objects disseminated within the environment with no centralized coordination. This paper presents an extended framework to enable u-KBs in mobile scenarios where a semantic discovery is carried out using metadata stored in RFIDs without fixed repositories. A dissemination protocol allows an on-demand retrieval of suitable descriptions directly from tags located on the objects. Such a vision allows to build a truly pervasive environment where autonomous objects compose a self-organized evolving discovery architecture suitable for u-Commerce purposes.

In this paper we propose an extended version of the open source jUDDI implementation by the Apache Software Foundation, adapted to pervasive RFID contexts. The registry \nadopts an OWL-S 1.1 Pro¯le instance annotation of mobile services and resources. Ontology-based metadata are \nexploited in order to perform a semantic-based service discovery w.r.t. a given request. The proposed framework \nhas been devised for pervasive RFID-based logistics environments. A case study is presented along with experimental results on a prototype implementation.

We present a novel resource discovery framework for u-commerce. Both the original RFID data exchange protocol and the Bluetooth Service Discovery Protocol have been extended in order to enable support for the semantic annotation of products and goods. Given a request, the approach we propose allows an enhanced discovery process exploiting the semantics of resource descriptions available in a u-marketplace. The enhancement is backward compatible with both the original discovery protocols, thus allowing the smooth coexistence of the resource discovery and/or identification approaches. We present and motivate our approach in an innovative u-commerce framework, and show its benefits.

We propose a collaborative environment for semantic-enabled mobile devices (e.g. PDAs, cell phones, laptops) in peer to peer scenarios. Within the environment, resource discovery is performed exploiting technologies and techniques for knowledge representation developed for the semantic Web, which have been adapted to cope with the highly flexible structure of ad-hoc networks in ubiquitous computing. The approach exploits the standard Bluetooth stack, using the original UUID payload, to carry semantically annotated data. The environment is motivated and presented in a museum case study.

Westwood+ TCP is a sender-side only modification of the classic TCP that is based on end-to-end estimation of the bandwidth available to the connection in order to shrink adaptively the TCP congestion window and the slow start threshold after congestion. We report measurements obtained using Linux implementations of Westwood+, Westwood and Reno to FTP data over Internet connections spanning continental and intercontinental distances. In particular, we show that the bandwidth estimation algorithm employed by Westwood+ nicely tracks the available bandwidth, whereas the previous bandwidth estimation algorithm used by TCP Westwood fails to work in the real Internet due to ACK compression. Collected live Internet measurements also show that Westwood+ improves the goodput, from 10% to 46%, with respect to TCP Reno.

In this paper we propose a formal method for web applications verification. The verification process is carried out by checking that either the system always satisfies a model of the specifications or by producing a counter-example.We represent the system as a Kripke structure and model a web site as a graph. Model checking is reformulated as checking that each initial state satisfies the specifications. We adopt Computation Tree Logic (CTL) as language to define the properties to be verified.The proposed formal method has been deployed in AnWeb, a tool for automatic support in the design of web applications. The tool provides an interface to the SMV model checker. The system parses the HTML source code of web pages, including code for dynamic pages, builds the model in SMV input language and provides the proper CTL specifications to the SMV tool.

Potentially, flexible manufacturing systems (FMSs) possess the ability to attain efficiency and versatility in small batches, variable mix production. However, the FMS potentiality is not yet fully used, because of the high cost of specific control software. Hence, a generic software, usable in an arbitrary FMS, producing an arbitrary part mix, appears as an important means to minimize programming and re-programming effort. In this context, modeling and control problem formalization emerge as a main issue. In this paper the authors refer to Zeigler's system-theoretic formalism for modeling the dynamics of a generic FMS at the job release and job how levels. The authors' discrete event dynamic system (DEDS) model establishes an abstract comprehensive framework for developing a generic control software at such levels. The model is able to represent both hardware/software components of the FMS and processing activity plans with a common "language". A modular structure underlies the description of both the shop-floor dynamics and control rules. So, the software architecture emerges as a direct consequence of the proposed approach and consists of three main parts: the system state knowledge base, the job release manager and the job flow manager.

Two different approaches for routing optimization are proposed and compared. The first method is open-loop and selects the route so that the job percentage on each alternative path approximates an optimal offline predetermined percentage. In the second approach decision-making is based on a merit index taking into account the current work in progress and the consequent machine availability, i.e., the current system's state. The decision is taken by comparing the index values for each one of the alternative paths allows for the job entering the system. Online simulation is used to estimate the near future system's state trajectory and to compute the merit index. Some case studies are presented comparing the method in terms of efficiency and implementation effort.>