WEB SERVICES COMMUNITIES - CONCEPTS & OPERATIONS

Zakaria Maamar, Mohammed Lahkim, Djamal Benslimane, Philippe Thiran and Subramanian Sattanathan

This paper discusses the concepts and operations related to the specification and management of a community of Web services, respectively. A Web service is an accessible application that humans and other peers can discover and trigger to satisfy multiple needs like hotel booking. Web services offering the same functionality are gathered into one community, independently of their origins. The community is led by a master component, which is responsible among others for attracting new Web services to the community, retaining existing Web services in the community, and identifying the Web services in the community that will participate in composite Web services. The identification of these Web services happens in accordance with the contract-net protocol. A demonstration of this protocol through a prototype is, also, presented in the paper.

STACK ENCODING REVISITED

Yangjun Chen

The twig join, which is used to find all occurrences of a twig pattern in an XML database, is a core operation for XML query processing. A great many strategies for handling this problem have been proposed and can be roughly classified into two groups. The first group decomposes a twig pattern (a small tree) into a set of binary relationships between pairs of nodes, such as parent-child and ancestor-descendant relations; and transforms a tree matching problem into a series of simple relation look-ups. The second group decomposes a twig pattern into a set of paths. Among all this kind of methods, the approach based on the so-called stack encoding [N. Bruno, N. Koudas, and D. Srivastava, Holistic Twig Hoins: Optimal XML Pattern Matching, in Proc. SIGMOD Int. Conf. on Management of Data, Madison, Wisconsin, June 2002, pp. 310-321] is very interesting, which can represent in linear space a potentially exponential (in the number of query nodes) number of matching paths. However, the available processes for generating such compressed paths suffer some redundancy and can be significantly improved. In this paper, we analyze this method and show that the time complexities of path generation in its two main procedures: TwigStack and TwigStackXB can be reduced from O(m2Þn) to O(mÞn), where m and n are the sizes of the query tree and document tree, respectively. Experiments have been done to compare TwigStackXB and ours, which shows that using our method much less time is needed to generate matching paths.

MODELING AND MANAGING FEDERATED WEB-BASED SYSTEMS

Johannes Meinecke, Martin Gaedke, Frederic Majer and Alexander Brändle

Among the various aspects of Web applications that are subject to modeling, like navigation, interaction or business processes, the architectural aspect is receiving growing attention. This is related to the fact that the Web is increasingly used as a platform for distributed services which transcend organizational boundaries to form so-called federated applications. In this context, we use the term “architecture” to denote the composition of the overall solution into individual Web applications and Web services that belong to different parties and invoke each other. The design and evolution of such systems calls for models that give an overview of the federation structure and reflect the technical details of the various accesses. We introduce the WebComposition Architecture Model (WAM) as an overall modeling approach tailored to aspects of highly distributed systems with federation as an integral factor.

ADJUSTMENT NEEDS IN SOA BASED E-LEARNING APPLICATIONS

Antonio Ortiz, Juan Manuel de Blas and José María Gutiérrez

This paper describes the solutions made to solve some interoperability issues found while carrying out an interconnection project of two SOA based systems. It is supposed that the solutions can help to avoid the problems in the future or solve incompatibilities. Both systems were developed using the same programming language, although they were based on different software platforms. These solutions are based on the analysis and the tests accomplished, where simple data structures were sent and received, using the Java language. This document also demonstrates the current state of interoperability in today’s frameworks, which are not fully compliant yet, and are still rather weak using complex data structures.

USING DATA TOGETHER WITH METADATA TO IMPROVE XML INFORMATION ACCESS

Alda Lopes Gançarski and Pedro Henriques

In this paper, we address the use of data together with metadata to improve information access to XML document collections. We first emphasize the possibility to associate meta-information to parts of XML documents, and not only entire documents. This is accordingly to the fact that XML elements are considered as retrieval units. We, then, propose to explicitly search the desired information using a query language that is composed of XML search and metadata search. We focus our ideas in two types of metadata: Dublin Core and ontologies.

COZO - CONTENT ZONING FOR SPAM EMAILS

Claudine Brucks, Cynthia Wagner, Michael Hilker and Ralph Weires

Spam is an increasing problem when using email as communication medium. Spam is detected and removed using spam filters. Furthermore, the spammers use more and more intelligent and complex techniques and novel approaches are required to enhance existing spam filters. One promising technique is the Argumentative Zoning that classifies a text in different parts where each part has a meaning. In this paper, we want to use this technique in order to fragment an email in different zones and evaluate whether the email is spam or not. We introduce the technique Content Zoning, the way we use it, the implementation, and our results.

MATCHING OF ENHANCED XML SCHEMAS WITH A MEASURE OF STRUCTURAL-CONTEXT SIMILARITY

Amar Zerdazi and Myriam Lamolle

Schema matching is a critical step in integration of heterogeneous data sources. Recent integration work has mainly focused on developing matching techniques to find equivalent elements among the different XML sources. In this paper we propose a new approach to structural similarity measure based on the notion of context, between entities of the Enhanced XML Schemas, called EXS. In our approach, the set of the EXS schemas, are considered like a federation of XML schemas descended of different heterogeneous sources schemas (relational, object, XML, etc.) and enriched by the semantic metaknowledge. We present here the major problems bound to this crucial task, notably with regard to the semantic of schemas. So, we propose a structural matching algorithm. The algorithm takes two schema graphs as input, and produces as output a mapping between corresponding nodes of the schema graphs. After our algorithm runs, we expect a human to check and adjust the results.

AN ONTOLOGY MAPPING ARCHITECTURE TO FACILITATE SEMANTIC INTEGRATION

Yingzi Wang, Deren Chen and Yanyun Wang

Mapping between ontologies is the major bottleneck in semantic integration. In this paper, we present MCMA, a mediator-centric mapping architecture that facilitates the integration between ontologies of interrelated companies. The main feature of MCMA is that different ontologies are mapped through some middle concepts and the Mapping Service acts as a bridge to connect them. In order to improve the similarity between ontologies, some common ontologies are provided for the reusing. On the assumption that the participators may make reference to common definitions while developing their individual ontologies, some basic mapping relations can be defined conveniently. Based on these basic mapping relations, the Mapping Service infers more mapping relations and organizes them in a layered manner. In MCMA, We present the idea of combining heuristics or machine-learning techniques with common ontology approach in the mapping discovery.

DISCOVERY CHALLENGES AND AUTOMATION FOR SERVICE-BASED APPLICATIONS IN GRID

Serena Pastore

Distributed environments like grid computing systems and web services frameworks pose service discovery challenges especially with regard to search for and find the best resource according some metric. Discovery is therefore a critical element in large scale, open distributed systems. Adequate tools must be implemented to facilitate dynamic identification, searching and finding of services in such infrastructures. In the framework of deploying grid web service-based applications for interacting with astronomical dataset, different discovery mechanisms have been evaluated. Solutions consist of methods coming from grid and web services specifications. The main hurdle of all these approaches is however a lack of automation. The paper describes the different methodologies analyzed in solving discovery challenges by dealing with the use case of a specific WSDL-based application. The need of automation has required the introduction of semantic components into the process both to discover and describe the application semantically. In this study, a possible solution whose technical implementation is under development has been outlined. By analyzing the actors and their transactions, semantic may be added in the interactions between an application provider and its client or directly to the broker whose role is to discover services for the client and to register application for the provider.

WEB SECURITY ENHANCEMENT BASED ON KEYSTROKE DYNAMICS

Michał Choras and Piotr Mroczkowski

Many online access systems (e.g. e-banking) require stronger protection than the login-id password pair can provide. Other, more sophisticated techniques of identity verification are in demand: one-time passwords, smart cards or biometric technologies. Among several biometric approaches the web-based solution that incorporates keystroke dynamics is the most relevant due to the low cost of the implementation, satisfactory results as well as the degree of transparency it offers. In the article we present methods of extracting user keystroke characteristics. Then we present results of our password hardening online access control system based on keystroke dynamics.

DISPATCHING REQUESTS IN PARTIALLY REPLICATED WEB CLUSTERS - AN ADAPTATION OF THE LARD ALGORITHM

Jose Daniel Garcia, Laura Prada, Jesus Carretero, Felix Garcia, Javier Fernandez and Luis Miguel Sanchez

raditional alternatives for Web content allocation have been full replication and full distribution. An hybrid alternative is partial replication where each content element is replicated to a subset of server nodes. Partial replication gives advantages in terms of balancing reliability and storage capacity. However, partial replication has architectural implications. In this paper we present a Web cluster architecture which may be used in single switched Web clusters and multiple switched Web clusters. We present an algorithm for Web content allocation which determines the number of replicas for each content based on its relative importance and that performs the allocation keeping in mind resource constraints in clusters with heterogeneous storage capacity. We also provide an adaptation of the LARD algorithm for request dispatching that copes with the fact that contents are partially replicated. Our evaluations show that performance of partial replication solutions is comparable to performance of traditional fully replicated solutions.

SEMANTICS-BASED ACCESS CONTROL - ONTOLOGIES AND FEASIBILITY STUDY OF POLICY ENFORCEMENT FUNCTION

Anton Naumenko

The current Web evolves to the Web 2.0 that is an intermediate step towards Semantic Web. Conventional security measures fall short to serve both, emerging Internet technologies and innovative web-based information systems. The paper presents our research and development results towards the consolidated framework of adoption Semantic Web standards for the creation of unified view on the access control area that enables flexible, collaborative and distributed management of access control based on semantic relations amongst relating concepts. The integration of Semantic Web and access control disciplines leads to the elaboration of new more intelligent, flexible and reusable access control mechanisms and tools. The paper has practical orientation, evaluating research results and ideas with the development and testing of the prototype for the enforcement of access control policies based on the ontologies.

A DESIGN PATTERN FOR AUTOMATIC GENERATION OF WEB SERVICES FROM DOMAIN ONTOLOGIES

Bob Dourandish, Nina Zumel and Michael Manno

Web Services and Service-Oriented Architecture have become ubiquitous and are increasingly embedded in every aspect of systems architecture. At the same time, advances in workflow tools now enable us to compose complex new applications by dynamically orchestrating existing web services in new and previously unanticipated execution sequences. The combination of the two is slowly transforming software engineering to a service-centric discipline, with the focus shifting from creating expansive systems to building small, specialized services that can be sequenced, on demand, to support previously unanticipated missions. Implementing and deploying specialized services in this way presents significant challenges in design and programming, as well as long-term maintenance. A fundamental challenge is to maintain the underlying program code long after it has been released and, potentially, incorporated in numerous other processes. This paper presents a methodology and a design pattern to automatically generate web services based on domain ontology. Our approach promises to significantly reduce the programming and maintenance burden of creating and deploying web services, particularly in mission-critical, collaborative, and distributed operations such as emergency response, supply-chain, or healthcare.

SECURITY RISK ANALYSIS IN WEB APPLICATION DESIGN

Rattikorn Hewett, Phongphun Kijsanayothin and Meinhard Peters

Web-based information systems play increasingly important roles in providing functions and business services for many organizations. Because of their ubiquitous natures dealing with a huge and diverse population of users, web applications must be tolerant to errors, adverse interactions and malicious attacks. The ability to quickly estimate security risks early in the system development life cycle can be beneficial in making various decisions. This is particularly crucial for large and complex web applications that are asset-critical and evolve rapidly through long life cycles. This paper presents a systematic approach for the automated assessment of security risks, at the design stage, of web-based information systems. The approach combines risk concepts in reliability engineering with heuristics using characteristics of software and hardware deployment design to estimate security risks of the system to be developed. It provides a simple early estimate of security risks that can help locate high-risk software components. We discuss limitations of the approach and give an illustration in an industrial engineering and business-to-business domain using a case study of a web-based material requirements planning system for a manufacturing enterprise.

A DECENTRALIZED WIKI ENGINE FOR COLLABORATIVE WIKIPEDIA HOSTING

Guido Urdaneta, Guillaume Pierre and Maarten van Steen

This paper presents the design of a decentralized system for hosting large-scale wiki web sites likeWikipedia, using a collaborative approach. Our design focuses on distributing the pages that compose the wiki across a network of nodes provided by individuals and organizations willing to collaborate in hosting the wiki. We present algorithms for placing the pages so that the capacity of the nodes is not exceeded and the load is balanced, and algorithms for routing client requests to the appropriate nodes. We also address fault tolerance and security issues.

DYNAMIC SERVICE COMPOSITION FOR VIRTUAL UPNP DEVICE CREATION IN HOME NETWORK ENVIRONMENT

Sheng-Tzong Cheng, Chun-Yen Wang, Mingzoo Wu, Wan-Ting Ho and Chia-Mei Chen

Exploiting UPnP techniques, home users can easily control intelligent devices through control points. However, UPnP devices lack a composition mechanism to complete a novel application or value-added service. This paper proposes a dynamic service composition system which coordinates the primitive UPnP services at home to create a virtual UPnP device. At first, we define data type ontology for UPnP devices to describe their service interfaces. Afterwards, the interface matching mechanism is employed to construct a service graph that describes which services can be composed together. Finally, the proposed system travels on the service graph, and probes a suitable execution path to generate a new device. Home users can invoke this new generated device through the control point, as if the device is real in the house. In addition, a virtual UPnP Karaoke device generated by the proposed service composition system is demonstrated as well. From the demonstration, it can be seen that the service composition system is feasible in practice.

ROBUSTNESS ANALYSIS USING FMEA AND BBN - CASE STUDY FOR A WEB-BASED APPLICATION

Ilaria Canova Calori, Tor Stålhane and Sven Ziemer

Time pressure and quality issues represent important challenges for those who develop web-based systems. The ability to analyze a system’s quality and implement improvements early in the development life cycle is of great practical importance. For our study we have considered robustness as a critical quality issue. Our objective is to propose a general framework for conducting robustness analysis of web-based systems at an early stage of software development, providing a tool for evaluating failure impact severity and supporting trade-off decisions during the development process. The framework makes use of Jacobson’s analysis method to decompose a system in its functional components, Failure Modes and Effects Analysis to identify all the failure modes that characterize each component, and Bayesian Belief networks to deal with failure cause-effect relationships and evaluate the uncertainty of their impact.

WEB SERVICE-BASED TRACEABILITY IN FOOD SUPPLY CHAINS

Andréia Akemi Kondo, Claudia Bauzer Medeiros, Edmundo Roberto Mauro Madeira and Evandro Bacarin

Supply Chains present many research challenges in Computing, such as the modeling of theirs processes, communication problems between theirs components, logistics and processes management. This paper presents a supply chain traceability model that relies on a Web service-based architecture to ensure interoperability. Geared towards assisting quality control in the agricultural domain, the model allows to trace products, processes and services inside chain. The model has been validated for real life case studies and the Web service implementation is under way.

PROVIDING SCALABLE ACCESS TO LARGE XML DOCUMENTS

Arno Puder

XML documents often tend to be voluminous and accessing them through a DOM (Document Object Model) interface poses particular challenges. All the existing DOM implementations require an XML document to be completely collocated before it can be parsed. This solution does not scale for huge XML documents. In this paper we introduce an architecture, called VDOM (Virtual DOM) that allows scalable access to large XML documents through a DOM interface. In the VDOM architecture, the actively used portions of an XML document are transferred to the application. The application can begin to traverse this portion without requiring that the complete DOM tree is collocated. As the application traverses the DOM tree, portions of the XML document are loaded on-demand. Using the VDOM architecture is transparent to the application which uses a standard DOM interface to access the DOM tree.

FUTURE TRUST FORECAST IN OPEN MOBILE AGENT ENVIRONMENT

Kłopotek A. Mieczysław and Wolski Michał

Open Mobile Agent Environment is composed of distributed entities that directly interact with each other and make local autonomous decisions in the absence of a centralized coordinating authority. Such decentralized applications, where entities can join and leave the system at any time, are particularly susceptible to the attacks of malicious entities. Hence intense studies of potential solutions of related problems are needed. A frequent approach is to use an appropriate simulator software. This paper presents the design of our Open Mobile Agent Simulator. We describe its behaviour and structure using the UML framework. We demonstrate the features of the simulator by comparing two reputation metrics (eBay and BetaSystem) for mobile agents travelling through different nodes. We show results of simulations comparing the effectiveness of reputation discovery using the original algorithm and the optimized (forecasting reputation) one.

PROCESSING REMOTE MEASUREMENT DATABASES BY THE MEANS OF MOBILE AGENTS

Steffen Kernchen, Dmytro Rud, Fritz Zbrog and Reiner Dumke

This paper discusses possible approaches for using mobile agents for accessing and processing of big remote databases containing measurement data. There are several reasons that make it inappropriate to dispatch raw data over the network. (a) Those data may be confidential and therefore need to be anonymized. (b) The amount of the data can be too big. In this case it could be advisable to generalize the data on the database provider node and to transfer only these generalization results to the customer. (c) Furthermore, this special information processing can be not in line with qualifications of both the database holder and its clients. The usage of agents gives the possibility to outsource the development and installation of additional software to an external agent provider, which is then responsible for regular updates of the software considering aspects like new algorithms. Application scenarios are outlined and certain kinds of service will be described and motivated with examples.

HARNESSING THE WEB TECHNOLOGY TO ENRICH VISUALLY CHALLENGED USERS NAVIGATION

Hulya Francis, Madjid Merabti and A. Taleb Bendiab

Navigating urban streets without sight is fraught with difficulty and is often dangerous. Visually challenged people rely on ancillary equipment such as a white cane to probe the immediate area in front of them as well as developing other pre-existing personal physiological senses such as tactile, auditory, and olfactory senses, to train themselves to walk along pavements. Conventional navigation systems based on geo-maps alone are of little use to a visually challenged pedestrian. Hence, there is a need to develop a navigation client-server system capable of providing information appropriate for a visually challenged pedestrian to use to navigate urban pavements. This paper describes a navigation system that includes an enriched information model and a technology to deliver such information in an easy-to-use, accessible fashion. The paper introduces the technical challenge to the creation of a digital database for the navigation server that stores appropriate data. A prototyped digital navigation model of Hoylake Town Centre has been used to test and validate the proposed model. This paper describes the role and function, and outlines the architecture for the Web-based mobile computing location-based services navigation support systems.

DYNAMIC DECENTRALIZED SERVICE ORCHESTRATIONS

Ustun Yildiz and Claude Godart

This paper reports a new approach to decentralized orchestration of service compositions. Our contribution is motivated by the recent advances of service orchestration standardizations that enable the exchange of modeled processes among different tools and organizations. Precisely, we provide an efficient process transformation technique that converts a process conceived for centralized orchestration to a set of nested \textit{peer processes}. Each peer process is conceived to be executed by a dynamically orchestrated service. Assuming that services are invokable with peer processes, we provide a decentralized orchestration setting where services can establish direct interconnections via the peer processes that they execute. Our proposition considers conversation-based services and dynamic service binding.

GRID INFRASTRUCTURE ARCHITECTURE - A MODULAR APPROACH FROM COREGRID

Augusto Ciuffoletti, Antonio Congiusta, Gracjan Jankowski, Michal Jankowski, Norbert Meyer and Ondrej Krajicek

The European Union {\em CoreGRID} project aims at encouraging collaboration among european research institutes. One target of such project is the design of an innovative Grid Infrastructure architecture, specifically addressing two challenging aspects of such entity: scalability and security. This paper outlines the results of such activity, ideally extending the content of the official deliverable document.

USER AND APPLICATION INTERFACE FOR A DISTRIBUTED E-LEARNING SYSTEM

Takao Kawamura, Kazuo Kuramochi, Junya Kishida, Shinichi Motomura and Kazunori Sugahara

In this paper, the user and application interface of our previously proposed e-Learning system is presented to demonstrate how user interfaces for distributed systems should be composed. The proposed e-Learning system has two distinguishing features. Firstly, it is based on P2P architecture for scalability and robustness. Secondly, all exercises in the system are not only data but also agents so that they have functions, such as scoring user's answers, telling the correct answers, and showing some related information without human instruction. The interface provides three kinds of communication: communication between a user and an exercise agent, communication between an exercise agent and support applications, and communication between a user and other users. The interface consists of two parts: an interface agent and a plugin for Firefox web browser. An interface agent hides the existence of the P2P network and other agents from the Firefox plugin and users. The developed e-Learning system including the interface is examined by experiments in classroom.

THE APPLICABILITY OF BALANCED ESI FOR WEB CACHING - A PROPOSED ALGORITHM AND A CASE OF STUDY

Carlos Guerrero, Carlos Juiz and Ramon Puigjaner

In this paper, we present an algorithm to improve the cases in which the caching of fragments pages (ESI standard) has a worse performance than expected. A layer between the web cache and the clients has been developed and has tested over a web application using a fragment and non fragment version of web pages. Through the results of this case study we demonstrate that the proposed algorithm improve the general performance of the web application.

NEW IMPLEMENTATION OF RMI TO PROTECT INTEGRITY AND CONFIDENTIALITY FOR MOBILE AGENTS

Shinichi Motomura, Takao Kawamura and Kazunori Sugahara

A new implementation of RMI named OnePort RMI is proposed in this paper. OnePort RMI consists of new RMI runtime, classes which are implemented interfaces by RMI specification, and MultiChannelSocketFactory. Using OnePort RMI, when an object on a client invokes methods of remote objects on a server, the client can use sockets of different types to connect one destination port at the same time, and the server can accept incoming call from the sockets on only the port. In order to protect integrity and confidentiality of our mobile agent framework named Maglog, OnePort RMI is introduced into Maglog. %In consequence, each agent can select a secure channel depending on In consequence, each agent can select a socket depending on importance of data and programs which are contained in their agents. We emphasize that the proposed OnePort RMI is not only for mobile agent frameworks such as our Maglog but also for any RMI applications.

DEVELOPING NEW SERVICES FOR THE AUTOMOTIVE INDUSTRY USING MATRIX

Silvia Alén, Daniel Glez-Peña and Florentino Fdez-Riverola

This progress report explores how multi-agent systems can be applied to the automotive industry in order to create an intercommunication platform. Our proposal called MATRIX (Multiagent Architecture for TRaffic Information eXchange) provides the basis for information exchange between cars (Car2Car) and between cars and infrastructural elements (Car2Infrastructure). In this work we also discuss how the most prominent technologies in both areas (JADE and OSGi) can be integrated in order to achieve new functionalities and security improvements in present cars.

SERVICE ORIENTED ATMOSPHERIC RADIANCES (SOAR) - A WEB SERVICE RESEARCH TOOL FOR THE GRIDDING AND SYNTHESIS OF MULTI-SENSOR SATELLITE RADIANCE DATA FOR WEATHER AND CLIMATE STUDIES

Milton Halem, Curt Tilmes, Yelena Yesha, Sharon Shen, Mitchell Goldberg and L. H. Zhou

Three decades of Earth remote sensing from NASA, NOAA and DOD satellites carrying successive generations of atmospheric instruments have resulted in petabytes of radiance data with successive increases in spatial and spectral resolutions stored at different data archives in various data formats. The complexity of accessing, processing and analyzing such varied massive data sets has hampered their utilization for climate studies by the general science community. We describe here the Service Oriented Atmospheric Radiance (SOAR) program sponsored by NASA to provide a web service tool that will enable more scientists to participate in the conduct of climate analysis with these valuable data records. SOAR is designed to respond to user requests to transparently access, collocate and perform spatial gridding operations on data from multiple instruments and transform the massive data volumes to reduced data structures in the more traditional grid format used in studying the trends in climate. SOAR is based on a service- oriented architecture employing the standard XML based protocol suite of SOAP, WSDL and UDDI service descriptions for aggregating atmospheric instrument radiance data into user specified spatial grids. SOAR consists of three subsystems, a Client Server, a Repository Server, and a Process Server, connected to a compute cluster and storage grid by a Service Bus. The process server employs optical communications to access data and invoke algorithms on the compute/storage cluster for on-demand spatial, temporal, and spectral subsetting Scientists can choose a variety of statistical averaging techniques for combining the footprints of satellite observed radiances from multiple instruments to form spatial-temporal grids for their respective studies. Animation services are also provided for viewing atmospheric anomalies. The results of a prototype web service version of SOAR, supporting client requests for arbitrary regional subsetting of high-resolution multi-instrument pre-gridded fields has been implemented. A second phase of SOAR capable of responding to client requests for arbitrary spatial grids derived from the raw data on demand is planned for the spring of 2007. The final phase will provide the broader community of Earth scientists a web service capability to invoke multi-sensor multi-satellite gridding algorithms for a 30-year data record to study global warming and their effects on regional weather and climate.

XLIVE: INTEGRATING SOURCES WITH XQUERY - AN EFFICIENT XQUERY EVALUATION PROTOTYPE WITH TGV

Nicolas Travers, Tuyêt-Trâm Dang-Ngoc and Tianxiao Liu

This paper presents an efficient evaluation of XQuery in a heterogeneous distributed system.XQuery(W3C, 2005) is a rich and so a complex language. Its syntax allows us to express a large scale of queries over XML documents. We have extended (Chen et al., 2003) proposal to rewrite XQuery expressions in "canonical XQuery" in order to support the full XQuery specification. The XQuery expressiveness makes difficulties to obtain an exclusive internal representation within a system.Models based on Tree Patterns have been proposed, and we have extended the tree pattern model to a model called TGV that (a) integrates the whole functionalities of XQuery (b) uses an intuitive representation that provides a global visualization of the request in a mediation context and (c) provides a support for optimization and for cost information.Our paper is based on the XLive mediation system. XLive integrates sources in a uniform view. It is a running research vehicle designed at PRiSM Laboratory for assessing the integration system at every stage of the process starting from sources extraction to the user interface and is already used in several projects.

WEB SERVICE RETRIEVAL BASED ON ENVIRONMENT ONTOLOGY

Budan Wu and Zhi Jin

Web Services are basic entities for Service Oriented Architecture whose goal is to build superior software system by reusing loose coupling software agents automatically and dynamically. Web Services are provided with various description format from providers, the understanding of Web Service capability is the prerequisite of retrieval and composition. The industry and academe bring forward some description and messaging standards to facilitate Web Service invoking, yet these descriptions of Web Service are in syntax level, and still relies on people to understand and decide what a Web Service can do, which encumbers automatic and dynamic Web Service retrieval. How to encode Web Service description in a computer-understandable form, and add enough semantics to depicting the capability of Web Service, is the key issue to solving the problem. In this paper, we propose environment ontology as the base of describing semantic of Web Services, whose resource and state transitions reflect Web Service’s behavior. We construct the description format based on environment ontology and put forward a road map approach towards automatic and dynamic Web Service retrieval.

ENSURING HIGH PERFORMANCE IN VALIDATING XML PARSER

Donglei Cao, Shuang Yu, Beijie Dai and Beihong Jin

An XML parser is the fundamental software for analyzing and processing XML documents. This paper presents the optimized validation algorithms in OnceXMLParser, a full-validating XML Parser. OnceXMLParser adopts a lightweight architecture and implements several efficient algorithms for validating. Since the element validating is a great challenge to the performance of a validating XML parser, this paper focused on two key algorithms to resolve it. The first one involves in an optimized automaton used to build these element validating rules efficiently. The second one is a statistical predictive algorithm to reduce the name string recognizing process. For a valid document, this algorithm could make precise prediction when the child elements are sequentially defined, and could fulfil the least cost prediction according to the cost function when the child elements are optionally defined. Performance testing shows OnceXMLParser after performance tuning has outstanding parsing efficiency.

A PERFORMANCE EVALUATION OF MOBILE WEB SERVICES SECURITY

Satish Narayana Srirama, Matthias Jarke and Wolfgang Prinz

It is now feasible to host basic web services on a smart phone due to the advances in wireless devices and mobile communication technologies. The market capture of mobile web services also has increased significantly, in the past years. While the applications are quite welcoming, the ability to provide secure and reliable communication in the vulnerable and volatile mobile ad-hoc topologies is vastly becoming necessary. Even though a lot of standardized security specifications like WS-Security, SAML exist for web services in the wired networks, not much has been analyzed and standardized in the wireless environments. In this paper we give our analysis of adapting some of the security standards, especially WS-Security to the cellular domain, with performance statistics. The performance latencies are obtained and analyzed while observing the performance and quality of service of our Mobile Host.

TRAP/BPEL - A FRAMEWORK FOR DYNAMIC ADAPTATION OF COMPOSITE SERVICES

Onyeka Ezenwoye and S. Masoud Sadjadi

TRAP/BPEL is a framework that adds autonomic behavior into existing BPEL processes automatically and transparently. We define an autonomic BPEL process as a compositeWeb service that is capable of responding to changes in its execution environment (e.g., a failure in a partner Web service). Unlike other approaches, TRAP/BPEL does not require any manual modifications to the original code of the BPEL processes and there is no need to extend the BPEL language nor its BPEL engine. In this paper, we describe the details of the TRAP/BPEL framework and use a case study to demonstrate the feasibility and effectiveness of our approach.

POSITION INFORMATION FOR VOIP EMERGENCY CALLS - ORIGINATING FROM A WIRELESS METROPOLITAN ACCESS NETWORK

Jaume Barceló, Boris Bellalta, Carlos Macián, Miquel Oliver and Anna Sfairopoulou

This article describes a mechanism to provide location information about users of a wireless metropolitan wireless access network to trusted and authorized third parties. A case of particular interest is that of pro- viding emergency centers with the location of the VoIP caller. The location information is obtained from the association tables of the wireless access points using SNMP polling, and stored in a location server. The outbound SIP proxy server requests the user’s location and includes it as in the SIP invite message when the callee is an emergency center.

WEWORM: AN ETHICAL WORM GENERATION TOOLKIT

Mark Wallis and Frans A. Henskens

One of the largest threats to network security in Internet-connected corporate networks is attack via worms. Worms infiltrate the network and compromise security, consuming processor cycles and network bandwidth that would otherwise be available for corporate use. This research analyses a particular strain of network worm called the “Ethical worm”, which is targeted towards beneficial means rather than malicious. Also presented is a design for an Ethical worm generation toolkit (named WEWorm) that will aid System administrators in the cleanup of an infected network.

WEB SERVICES-BASED QUERY REWRITING AND RESOLUTION IN LOOSELY COUPLED INFORMATION SYSTEMS

Mahmoud Barhamgi, Pierre-Antoine Champin and Djamal Benslimane

Recent research works in Peer-to-peer data management systems have focused on integrating and inter-operating traditional data sources, where usually data portions are put in forms like XML, RDFS/OWL instances. Then, received queries are directly applied on data in order materialize the answers. However, recently a great deal of information resources has been exposed in the form of Data-Providing Web services in Peer-to-peer based e-collaboration environments. With this new form of data accessibility, queries can not be applied squarely on data, rather they should be resolved by composing available Data-Providing Web services. In this paper, we extend previous P2P data management systems with capability to handle data sources exposed as services. In our solution we model Data-providing services as RDF parameterized views. Then we devise an algorithm capable to compute the different data-providing services' compositions that answer the received query. Our composition is Data-Driven, therefore we apply extra data treatments on data flow between composed services before getting the desired result.

A COLLABORATIVE FILTERING APPROACH TO PERSONALIZED INTERACTIVE ENTERTAINMENT USING MPEG-21

Giorgos Andreou, Phivos Mylonas and Kostas Karpouzis

In this paper we present an integrated framework for personalized access to interactive entertainment content, using characteristics from the emerging MPEG-21 standard. Our research efforts focus on multimedia content presented within the framework set by today’s movie content broadcasting over a variety of networks and terminals, i.e. analogue and digital television broadcasts, video on mobile devices, personal digital assistants and more. This work contributes to the bridging of the gap between the content and the user, providing end-users with a wide range of real-time interactive services, ranging from plain personalized statistics and optional enhanced in-play visual enhancements to a fully user- and contentadaptive platform. The proposed approach implements and extends in a novel way a well-known collaborative filtering approach; it applies a hierarchical clustering algorithm on the data towards the scope of group modelling implementation. It illustrates also the benefits from the MPEG-21 components utilization in the process and analyzes the importance of the Digital Item concept, containing both the (binary) multimedia content, as well as a structured representation of the different entities that handle the item, together with the set of possible actions on the item. Finally, a use case scenario is presented to illustrate the entire procedure. The core of this work is the novel group modelling approach, on top of the hybrid collaborative filtering algorithm, employing principles of taxonomic knowledge representation and hierarchical clustering theory. The outcome of this framework design is the fact that end-users are presented with personalized forms of multimedia content, thus enhancing their viewing experience and creating more revenue opportunities to content providers.

A PERFORMANCE MODELLING OF WEB SERVICES SECURITY

Kezhe Tang, David Levy, Shiping Chen, John Zic and Bo Yan

While Web Services Security (WSS) enhances the security of web services, it may also introduce additional performance overheads to standard web services due to additional CPU processing and larger message sizes. In this paper, we present a simple performance model for WSS. Based on our observations of WSS performance in our previous work, we extend a web service performance model by modelling WSS extra security operations and increased messages sizes into the existing model. As fitting the parameters on one testing environment, we validate our performance model on another different environment with different messages sizes and WSS security policies. Our testing results show that our performance model is valid and can be used to predicate the performance of web services with a variety of WSS configurations.

IMPLEMENTATION OF INDEX SCHEMA FOR XML DOCUMENTS BASED ON STRUCTURE OF DATABASE

Youngrok Song, Kyonam Choo, Yoseop Woo and Hongki Min

In this paper, structural information between tree nodes is presented without any structural changes in tree by converting number information added to tree into bit streams. It is also shown that other structural information can be retrieved and added to index schema, and that in query schema it is possible to restore host nodes by exploiting the given node information in case relative route query expressions as well as absolute query expressions are given. It has an advantage of making derived query expressions through a query. In addition, in the query-processing process, response time can be minimized by conducting bit operation between bit streams with index schema and query schema in use, and accurate results can be reached by searching only with information of record set by node in index files.

END USER AUTHENTICATION (EUA)

George S.Oreku, Jianzhong Li and Fredrick J. Mtenzi

AbAuthentication is one among a set of services that constitute a security sub-system in a modern computing or communications infrastructure. End User Authentication flexibility model would proposed in this paper allow the user to have multiple authentication mechanisms with varying levels of guarantee, and for suppliers to request and rely on mechanisms appropriate to the service requested. Authentications to end-user in a simple three level ticket request model algorithms solution on open distributed environment. This paper describes the ticket used by clients, servers, and Kerberos to achieve authentication toward prevention of unauthorized access to in sourced data on applications level. However we explore an approach to end user authentication that generalizes the notion of a textual password that, in many cases, improves the security. Our approach is based on the use of Kerberos authentication technique and Diffie-Hellman Key exchange.

TUNING SEARCH ENGINE TO FIT XML RETRIEVAL SCENARIO

Kurt Englmeier, Gilles Hubert and Josiane Mothe

XML usage is growing to describe documents. Consequently, systems to search in XML collections are necessary. Various proposals of systems for XML retrieval intend to provide solutions to handle XML documents. This paper describes an XML approach based on direct contribution of the components constituting an information need. The search engine is largely configurable in order to be adapted to different context of search. Beyond being globally adapted to a collection of documents an important objective is to define a search engine that can be adapted to different retrieval scenarios and to identify how to adapt it. This paper presents first experiments on INEX testbeds that show how the engine can be adapted to better respond to different retrieval scenarios.

A NETWORK-BASED ANOMALY DETECTION SYSTEM USING MULTIPLE NETWORK FEATURES

Yuji Waizumi, Yohei Sato and Yoshiaki Nemoto

Accuracy of anomaly-based intrusion detection greatly depends on features, the numerical values representing characteristics of network trafc. In order to increase accuracy, it is necessary to choose appropriate features that can correctly detect anomalous events. In this paper, we stress the fact that a specic kind of anomaly changes specic features. We propose a highly accurate and robust intrusion detection system using multiple features. Each feature is used for evaluating anomalous events independently by a statistical detection method. Through experiments, we investigate the accuracy of the proposed scheme.

A LOW COST WORM DETECTION TECHNIQUE BASED ON FLOW PAYLOAD SIMILARITY

Youhei Suzuki, Yuji Waizumi, Hiroshi Tsunoda and Yoshiaki Nemoto

Recently, damages of information systems by worms have been reported at global level. Signature based Intrusion Detection Systems (IDSs) are widley used to prevent these damages. To handle newly created worms, automatic signature generation techniques based on common strings in the payloads of multiple worm flows of the same kind have been proposed. Because these techniques need to use multiple strings as a signature for each kind of worm to acheive high detection accuracy, the calculation cost to detect worms is a serious issue. In this paper, we propose a novel scheme that does not use common character strings. The proposed scheme uses a 256-dimensional vector based on the appearance frequencies of 256 character codes. This vector is used as a mean to detect worms with low cost. In addition, we construct a cheap worm detection system by using the proposed method as the first stage analysis of conventional IDS. We evaluate the proposed scheme through experiments and present its performance.

A NOVEL APPROACH OF ALARM CLASSIFICATION FOR INTRUSION DETECTION BASED UPON DEMPSTER-SHAFER THEORY

Huiqiang Wang, Guangsheng Feng and Qian Zhao

As the number of the alarms is increasingly growing, which are generated by intrusion detection systems (IDS), automatic tools for classification have been proposed to fulfil the requirements of the huge volume of alarms. In addition, it has been shown that an accurate classification requires the evidences from different sources, such as different IDS. Further more, Dempster-Shafer theory is a powerful tool in dealing with the uncertainty information. This paper proposes multiple-level classification model, which aims to classify the large sizes of alarms exactly. Experimental results show that this approach has an outstanding capability of classification. Especially it is quite effective in avoiding alarms grouped into the wrong classes in the case of short of evidences.

MODELING ARCHITECTURAL LEVEL REPAIR IN WEB SERVICES

Francisco Moo-Mena and Khalil Drira

Failures during Web service execution may depend on a wide variety of causes, such as network faults, server crashes, or application-related errors, such as unavailability of a requested Web service, errors in the orchestration or choreography of applications, missing data or parameters in an execution flow, or low Quality of Service (QoS). Providing efficient solutions requires handling of adaptability not only at the behavioral level, but also at the architectural level. Most of existing standard solutions focus on the behavioral level using reconfiguration mechanisms. In this paper, we propose a model-based strategy providing adaptability actions at the architectural level. Typical architectural repair actions, such as duplication of services or substitution of a faulty service are introduced. An example is illustrated and discussed with respect to a running example involving coordinated Web services.

DESIGN AND IMPLEMENTATION PRINCIPLES FOR INTEGRATED NETWORK AND SYSTEM MANAGEMENT

Martin H. Knahl

A significant number of IT systems are managed in an ad hoc style without an overall plan and lack appropriate Network and System Management tools for the provision of integrated Management Services. This paper provides an analysis of the requirements for Management Services. The paper presents a framework that provides a basis for the planning and operation of Management Services. Management Systems are divided into different functional areas and can be derived from a set of Building Blocks in order to accommodate the range of requirements and environments applicable to Integrated Service Management. The paper further presents ways to utilize SW implementations for the provision of integrated Management Services based on the proposed principles. The construction and maintenance of Management Systems is facilitated by the use of existing solutions.

AN OPTIMAL EVALUATION OF GROUPBY-JOIN QUERIES IN DISTRIBUTED ARCHITECTURES

Mohamad Al Hajj Hassan and Mostafa Bamha

SQL queries involving join and group-by operations are fairly common in many decision support applications where the size of the input relations is usually very large, so the parallelization of these queries is highly recommended in order to obtain a desirable response time. Several parallel algorithms that treat this kind of queries have been presented in the literature. However, their most significant drawbacks are that they are very sensitive to data skew and involve expansive communication and Input/Output costs in the evaluation of the join operation. In this paper, we present an algorithm that overcomes these drawbacks because it evaluates the "GroupBy-Join" query without the need of the direct evaluation of the costly join operation, thus reducing its Input/Output and communication costs. Furthermore, the performance of this algorithm is analyzed using the scalable and portable BSP (Bulk Synchronous Parallel) cost model which predicts a linear speedup even for highly skewed data.

POLICY-BASED MANAGEMENT OF DIFFSERV USING XML TECHNOLOGIES

Ntanzi M. Carrilho and Neco Ventura

A design, implementation, and evaluation of a Policy-based Management framework for DiffServ networks using XML technologies is presented. XML is used for policy representation throughout the entire policy life cycle, as well as in the communication protocol, reducing development costs, while promoting clarity, simplicity, and interoperability. Furthermore, performance evaluation results show that the proposed scheme generates less network traffic than its COPS-PR counterpart when protocol messages are compressed. Moreover, XML messages generate higher processing delays. The added processing overhead caused by compression to XML messages is very small, thus the gains in reduced network traffic generated outweigh the losses in terms of processing overhead.

A FRAMEWORK FOR THE MANAGEMENT OF CONTEXT-AWARE WORKFLOW SYSTEMS

Liliana Ardissono, Roberto Furnari, Anna Goy, Giovanna Petrone and Marino Segnan

This paper presents the CAWE framework for the context-aware management of applications based on the composition of Web Services in complex workflows. We introduce a representation of context-dependent activities based on an abstraction hierarchy which supports the specification of synthetic and clear workflows. Moreover, we propose a framework architecture which enriches the capabilities of a workflow engine in order to support the execution of possibly complex adaptation rules. We have exploited the CAWE framework to develop a prototype application handling a medical guideline which specifies the activities to be performed in order to monitor patients treated with blood thinners from their home. The application coordinates actors playing different roles (e.g., patient, doctor, etc.) and can be accessed by using different client devices.

THE PRIVACY ADVOCATE (PRIVAD) - A FRAMEWORK FOR NEGOTIATING INDIVIDUAL PRIVACY CONTRACTS

Michael Maaser, Steffen Ortmann and Peter Langendörfer

Privacy has been a hot topic in research for several years. A lot of different approaches to protect privacy have been proposed recently. Among these are several tools for negotiation of privacy contracts. In this paper we present our privacy negotiation framework called “Privacy Advocat (PrivAd)”. It consists of three main parts: the policy evaluation unit, the signature unit and the preferences. In addition our frame supports an interface for negotiation strategies, so that they are independent of the framework. The preferences can be expressed with a combination of P3P and APPEL. The test we executed using a state of the art PDA clearly indicate that our framework can be used by mobile devices. The completion of a negotiation takes about 2 sec. including message transfer via an 802.11b wireless link. The processing itself is done in less than 250 msec.

ERLANG/OTP FRAMEWORK FOR COMPLEX MANAGEMENT APPLICATIONS DEVELOPMENT

Carlos Abalde, Víctor M. Gulías, Laura M. Castro, Carlos Varela and J. Santiago Jorge

This paper presents our experience in the development of a large scale management client/server application, using the distributed functional language Erlang. We will explain our ideas about how to evolve a first and early architecture to a more sophisticated one, which could be reused in other developments, significantly reducing the development life cycles of future versions. We also expose some problems that arised in the process and suggest some solutions. The use of the proposed architecture, some formal verification techniques, and an interface definition language, let us glimpse a framework with similar features to those which have made J2EE so popular, with the additional benefits inherited from the declarative languages area.

SPECIFICATION-BASED INTRUSION DETECTION SYSTEM FOR CARRIER ETHERNET

Pan Jieke, João Redol and Miguel Correia

Layered network architectures, like the OSI and TCP/IP models, separate functionality in layers, where the lower layers provide services for the higher layers. These flexible models provide a form of separation of concerns, which allows the layers to be designed and implemented independently. However, from the security point of view, once a lower layer is compromised, the reliability of the higher layers can also be affected. This paper is about the security of the Data Link Layer (layer 2) of the OSI model, which can affect the reliability of higher layers, like TCP or HTTP and other World-Wide Web protocols. The paper analyzes security-wise a layer 2 protocol – the Spanning Tree Protocol (STP), part of the Ethernet suite – and presents a solution to detect attacks against this protocol using Specification-based Intrusion Detection.

ACCELERATING XPATH AXES THROUGH STRUCTURAL PARTITIONING

Olli Luoma

The query evaluation algorithms of practically all XML management systems are based on structural joins, i.e., operations which determine all occurrences of parent/child, ancestor/descendant, preceding/following etc. relationships between node sets. In this paper, we present a simple method for accelerating structural joins which is very easy to implement on different platforms. Our idea is to split the nodes into disjoint partitions and use this information to avoid unnecessary structural joins. Despite its simplicity, our proposal can considerably accelerate XPath evaluation on different XML management systems. To exemplify this, we describe two implementation options of our method - one built from the scratch and one based on a relational database - and present the results of our experiments.

ANALYSIS OF WEB-PROXY CACHE REPLACEMENT ALGORITHMS UNDER STEADY-STATE CONDITIONS

Luis Guillermo Cárdenas, Ana Pont, Julio Sahuquillo and José Antonio Gil

Web-Proxy servers are used to reduce the bandwidth consumption and users’ perceived latency while navigating the WWW, by caching the most frequent objects accessed by users. Since they were introduced most of the evaluations studies related to Web-Proxy caches have focused on the replacement algorithms performance using simulation techniques. But few of them have been done assuring the representativeness of the studies and considering real traces and cache sizes. This paper describes a methodology that permit fair performance comparison studies of the replacement algorithms i.e., the system reaches the steady-state and the results are provided showing narrow confidence intervals. An experimental evaluation study applying this methodology is also presented. The study uses a trace-driven simulation framework, real traces containing more than one hundred million of user’s requests, and compares three replacement algorithms implemented in actual Web-Proxy caches.

DISTRIBUTED BLOOM FILTER FOR LOCATING XML TEXTUAL RESOURCES IN A P2P NETWORK

Clément Jamard, Laurent Yeh and Georges Gardarin

Nowadays P2P information systems are considered as large scale distributed databases where all peers can publish and query data in the network. The main challenge for query processing remains locating relevant resources. In the case of XML documents, keywords and structures must be indexed. However, the major problem for maintaining indexes of huge textual XML documents is the cost for connecting/disconnecting and updating: Indexing a quantity of keys or propagating updates requires the transit of many messages in the network. To reduce this cost, we adapt the Bloom Filter principle (a data structure for testing membership of an element in a set) to summarize peer content. Our Bloom Filter summarizes both structures and values of XML documents and is used to locate resources in a P2P network. The originality of our approach is to propose techniques to distribute the Bloom Filter by splitting it into segments using a DHT network. As experiments demonstrate, the system is scalable and reduce drastically the number of network messages for indexing data, maintaining the index, and locating resources.

ON THE INTEGRATION OF QOS MANAGEMENT IN WEB SERVICE ARCHITECTURE

Abdallah Missaoui and Kamel Barkaoui

The web service consumer requires sometimes a service provider which gives functional and non-functional requirement especially in e-business domain. In this paper, an overview on web services and their qualities are described. We propose a new architecture which permits the management of QoS, by integrating a new layer in the web service architecture.

DYNAMIC PROVISIONING AND MONITORING OF STATEFUL SERVICES

Peter Tröger, Harald Meyer, Ingo Melzer and Marcus Flehmig

While tools for service-oriented architectures promise a seamless combination of stateless basic services to new applications, reality looks different. Real-world services wrap stateful behavior using application-specific concepts (e.g. session identifiers) and use different variations of Web protocols. The monitoring of these services, needed for dynamic re-composition facilities, is only available through vendor-specific interfaces. Services are bound to particular execution hosts, where load balancing and fault tolerance are only achievable with expensive low-level solutions. We present the ASG Services Infrastructure (SI) architecture as our practical solution to real-world service integration issues. Our framework is based on established Web service standards and supports the dynamic hosting and monitoring of heterogeneous and stateful service implementations. The resulting reference implementation currently acts as service infrastructure provider for the Adaptive Services Grid research project.

TRADE-OFF’S IN WEB APPLICATION DEVELOPMENT - HOW TO ASSESS A TRADE-OFF OPPORTUNITY

Sven Ziemer and Tor Stålhane

This paper discusses a trade-off strategy for small projects and presents a preliminary guidelines for assessing the appropriateness of a trade-off. The motivation of this work is to make the development team aware of the performed trade-offs and to see both the associated opportunities and risks, to assess the appropriateness of a trade-off and to gather information for the future development of the system. The development environment of a web application is changing over time and it is important to know what the success criteria are at any time.

THE EFFECT OF PACKET LOSS ON THE RESPONSE TIMES OF WEB SERVICES

Johan Garcia, Per Hurtig and Anna Brunstrom

Web services have today become an important technology for information exchange over the Internet. Although web services are designed to support interoperable machine-to-machine interaction, humans are often the final recipients of the produced information. This makes the performance of web services important from a user perspective. In this paper we present a comprehensive experimental evaluation on the response times of web services. The limited amount of data transfered in a typical web service message makes its performance sensitive to packet loss in the network and we focus our investigation on this issue. Using a web service response time model, we evaluate the performance of two typical web services over a wide range of network delays and packet loss patterns. The experiments are based on network emulation and two real protocol implementations are examined. The experimental results indicate that a single packet loss may more than double the response times of the evaluated services and lead to noticeable delays for the end user. We briefly review previous solutions that can be applied to improve performance and outline an improved approach that is based on packet loss detection at the receiver.

3D MONITORING OF DISTRIBUTED MULTIAGENT SYSTEMS

Sergio Ilarri, Juan L. Serrano, Eduardo Mena and Raquel Trillo

In the last years, multiagent systems have been proposed to solve a wide range of applications in distributed contexts, as they provide many advantages, such as parallelism, robustness, and scalability. A key element for the performance and reliability of the multiagent system is to design carefully the interaction and synchronization among the agents. Particularly, debugging and monitoring multiagent systems is a challenging task, due to the number of agents involved and the complex communication patterns that they may exhibit. In this paper, we present a 3D interactive monitoring framework that we have developed to observe how the agents in a multiagent system communicate among themselves and other interesting events. It offers many desirable features, such as the possibility of analyzing the communications and events in real-time, or perform a query-based filtering of the relevant or problematic events. Besides, the framework can be easily customized and extended in order to debug a variety of multiagent systems.

WSRS: A WEB SERVICE RECOMMENDER SYSTEM

Esma Aïmeur, David Daboue, Flavien Serge Mani Onana, Djamal Benslimane and Zakaria Maamar

Despite Web services widespread adoption, users still struggle with the problem of locating the Web services that best satisfy their needs and meet their requirements. Unfortunately, current Web services repositories suffer from various limitations, such as providing Web services to users regardless of these users’ past experiences and these Web services’ intrinsic characteristics like popularity and credibility. In this paper, we introduce a Web Service Recommender System (WSRS) that uses three techniques, namely collaborative filtering, demographic filtering, and content-based filtering, to help facilitate the search of Web services. The WSRS system has the capacity to take into account the profile of both users and Web services in the process of recommending Web services.

XML BASED FRAMEWORK FOR CONTACT CENTER APPLICATIONS

Nikolay Anisimov, Brian Galvin and Herbert Ristock

W3C languages, VoiceXML and CCXML all play an important role in contact centers (CC) by simplifying the creation of CC applications. However, they cover only a subset of contact center functions, such as simple call control and interactive voice response (IVR) with automatic speech recognition. We discuss ways to complement VoiceXML and CCXML in order to cover all necessary contact center functions required to script end-to-end interactions in a consistent and seamless way. For this purpose we introduce an XML forms-based framework called XContact comprising the CC platform and applications, multi-script and multi-browsing, and interaction data processing. We also discuss how routing as a key CC capability can be scripted/captured within such framework in order to demonstrate the overall approach

A FLEXIBLE MODEL FOR PROVIDING TRANSACTIONAL BEHAVIOR TO SERVICE COORDINATION IN AN ORTHOGONAL WAY

Alberto Portilla, Genoveva Vargas-Solar, Christine Collet, José-Luis Zechinelli-Martini and Luciano García-Bañuelos

A key step towards consistent services coordination is providing non functional properties. In that sense,transactional properties are particularly relevant because of the business nature of current applications. While services composition has been successfully addressed, transactional properties have been mainly provided by ad-hoc and limited solutions at systems' back end. This paper proposes a flexible transactional behavior model for services coordination. We assume that given a flow describing the application logic of a service based application, it is possible to associate to it a personalized transactional behavior in an orthogonal way. This behavior is defined by specifying contracts and associating a well defined behavior to the activities participating in the coordination. Such contracts ensure transactional properties at execution time in the presence of exceptions.

A GRAPH-BASED APPROACH FOR WEB SERVICES COMPOSITION

Salima Benbernou, Djamal Benslimane, Mohand Said Hacid, Hamamache Kheddouci and Kamel Tari

The automatic web services composition plays an important role in the area of semantic web services. In fact, in a real life it is not usual to discover \textit{atomic} web services matching with the user's query. So composing services fulfilling the query is needed. This paper discusses the web services composition model based on an oriented graph. It is based on Bcov algorithm \cite{Benatallah05,Farouk05}, initially defined for web services discovery. We propose two algorithms handling the oriented graph reasoning for web service composition. At first glance, a basic composition version for Bcov algorithm is given. That algorithm composes services over the induced subgraphs of each transversal provided by Becov algorithm, and gives a covering ratio satisfying the query. The second algorithm used a composed services graph maintained by a web services provider. The composition in that case is based on Dijkstra algorithm, where for each two consecutive services in the best minimal transversal provided by Bcov algorithm, a shortest path is computed regarding the composed services graph.

THE DATA COLLECTION MODULE OF THE AGENT BASED SEARCH SYSTEM (ABSS)

Remigiusz Baran, Andrzej Zeja, Tomasz Orzechowski, Andrzej Dziech and Michał Lutwin

The main purpose of this paper is analysis and description of the Data Collection Module (DCM) that is the main unit of the ABSS system. The aim of the DCM module is to process the metadata for the learning resources and preparing them for the search algorithms. The components of the DCM module are analysed with respect to technologies and standards used to their implementation. Advantages of proposed solutions are also discussed. The subject of the paper is related to the Calibrate (Calibrating eLearning in Schools) project.

MODELING BPEL WEB SERVICES FOR DIAGNOSIS: TOWARDS SELF-HEALING WEB SERVICES

Yingmin Li, Tarek Melliti and Philippe Dague