Web Engineering

Project repositories are a central asset in software development, as they preserve the technical knowledge gathered in past development activities. However, locating relevant information in a vast project repository is problematic, because it requires manually tagging projects with accurate metadata, an activity which is time consuming and prone to errors and omissions. This paper investigates the use of classical Information Retrieval techniques for easing the discovery of useful information from past projects. Differently from approaches based on textual search over the source code of applications or on querying structured metadata, we propose to index and search the

models

of applications, which are available in companies applying Model-Driven Engineering practices. We contrast alternative index structures and result presentations, and evaluate a prototype implementation on real-world experimental data.

GML is emerging as the new standard for representing geographic information in GISs on the Web, allowing the encoding of structurally and semantically rich geographic data in self describing XML-based geographic entities. In this study, we address the problem of approximate querying and ranked results for GML data and provide a method for GML query evaluation. Our method consists of two main contributions. First, we propose a tree model for representing GML queries and data collections. Then, we introduce a GML retrieval method based on the concept of tree edit distance as an efficient means for comparing semi-structured data. Our approach allows the evaluation of both structural and semantic similarities in GML data, enabling the user to tune the querying process according to her needs. The user can also choose to perform either

template

querying, taking into account all elements in the query and data trees, or

minimal constraint

querying, considering only those elements required by the query (disregarding additional data elements), in the similarity evaluation process. An experimental prototype was implemented to test and validate our method. Results are promising.

Autocompletion services help users in formulating queries by exploiting past queries. In this paper we propose methods for improving such services; specifically methods for increasing the number and the quality of the suggested “completions”. In particular, we propose a novel method for partitioning the internal data structure that keeps the suggestions, making autocompletion services more scalable and faster. In addition we introduce a ranking method which promotes a suggestion that can lead to many other suggestions. The experimental and empirical results are promising.

The use of patterns in data management is not new: in data warehousing, data marts are simple conceptual schemas with exactly one core entity, describing facts, surrounded by multiple entities, describing data analysis dimensions; data marts support special analysis operations, such as roll up, drill down, and cube. Similarly, Service Marts are simple schemas which match "Web objects" by hiding the underlying data source structures and presenting a simple interface, consisting of input, output, and rank attributes; attributes may have multiple values and be clustered within repeating groups. Service Marts support Search Computing operations, such as ranked access and service compositions. When objects are accessed through Service Marts, responses are ranked lists of objects, which are presented subdivided in chunks, so as to avoid receiving too many irrelevant objects – cutting results and showing only the best ones is typical of search services. This paper gives a formal definition of Service Marts and shows how Service Marts can be implemented and used for building Search Computing applications.

Modern Web applications are often hosted in a virtualized cloud computing infrastructure, and can dynamically scale in response to unpredictable changes in the workload to guarantee a given service level agreement. In this paper we propose to use Kriging surrogate models to approximate the performance profile of virtualized, multi-tier Web applications. The model is first built through a set of automated and controlled experiments at staging time, and can be later updated and refined by monitoring the Web application deployed in production. We claim that surrogate modeling makes a very good candidate for a model-driven approach to the engineering of an autonomic controller. Our experimental evaluation shows that the model predictions are faithful to the observed system’s performance, they improve with an increasing amount of samples and they can be computed quickly. We also provide evidence that the model can be effectively used to synthetize an aggregated objective function, a critical component of the autonomic controller. The approach is evaluated in the context of a RESTful Web service composition case study deployed on the RESERVOIR cloud.

The problem of service differentiation and admission control in web services that utilize a multi-tier architecture is more challenging than in a single-tiered one, especially in the presence of bursty conditions, i.e., when arrivals of user web sessions to the system are characterized by temporal surges in their arrival intensities and demands. We demonstrate that classic techniques for a session based admission control that are triggered by threshold violations are ineffective under bursty workload conditions, as user-perceived performance metrics rapidly and dramatically deteriorate, inadvertently leading the system to reject requests from already accepted user sessions, resulting in business loss. Here, as a solution for service differentiation of accepted user sessions we promote a methodology that is based on blocking, i.e., when the system operates in overload, requests from accepted sessions are not rejected but are instead stored in a blocking queue that effectively acts as a waiting room. The requests in the blocking queue implicitly become of higher priority and are served immediately after load subsides. Residence in the blocking queue comes with a performance cost as blocking time adds to the perceived end-to-end user response time. We present a novel autonomic session based admission control policy, called

AWAIT

, that adaptively adjusts the capacity of the blocking queue as a function of workload burstiness in order to meet predefined user service level objectives while keeping the portion of aborted accepted sessions to a minimum. Detailed simulations illustrate the effectiveness of

AWAIT

under different workload burstiness profiles and therefore strongly argue for its effectiveness.

Service Level Agreements (SLAs) are used in Service- Oriented Computing to define the obligations of the parties involved in a transaction. SLAs define these obligations, including for instance the expected service levels to be delivered by the provider, and the payment expected from the client. The obligations of the parties must be made explicit prior to the transaction, and a mechanism should be available to control the interaction, in order to ensure that the obligations are met. We outline a norm-oriented multiagent system (NoMAS) architecture that is combined with the service-oriented architecture in order to support the definition, management, and control of SLAs between the service clients and service providers.

Due to the availability of huge number of Web services (WSs), finding an appropriate WS according to the requirement of a service consumer is still a challenge. In this paper, we present a new and flexible approach, called SeqDisc, that assesses the similarity between WSs. In particular, the approach exploits the Prüfer encoding method to represent WSs as sequences capturing both semantic and structure information of service descriptions. Based on the sequence representation, we develop an efficient sequence-based schema matching approach to measure the similarity between WSs. A set of experiments is conducted on real data sets, and the results confirm the performance of the proposed solution.

Future Web applications will increasingly require real-time data from the physical world collected by a myriad of sensors and actuators. Currently, integration of such devices require customized solutions due to the lack of widely adopted protocols for devices. Because the Web architecture offers a high degree of interoperability and a low entry barrier, we propose to leverage the Web to build hybrid applications that combine the physical world with Web content. Our work builds upon recent developments in Web push techniques and extends them for embedded devices with a RESTful messaging system. Our results illustrate that fully Web-based distributed sensing applications are not only feasible - but actually desirable - because Web standards offer an ideal compromise between performance and functionality.

The prevalence of RESTful services requires that we pay closer attention to how the principles that underlay REST are realized in actual services being implemented. This is especially crucial as REST is being applied to problem domains that require complex operations such as transactions. In this paper we investigate the relationship between RESTful web services and the actor model of computation. We suggest that by formulating RESTful services as a network of actors we can achieve deeper understanding what it means for a service to be RESTful.

Model Driven Engineering (MDE) advocates the use of models and transformations to support all the tasks of software development, from analysis to testing and maintenance. Modern MDE methodologies employ multiple models, to represent the different perspectives of the system at a progressive level of abstraction. In these situations, MDE frameworks need to work on a set of interdependent models and tranformations, which may evolve over time. This paper presents a model transformation framework capable of aligning two streams of transformations: the forward engineering stream that goes from the Computation Independent Model to the running code, and the testing stream that goes from the Computation Independent Test specification to an executable test script. The “vertical” transformations composing the two streams are kept aligned, by means of “horizontal” mappings that can be applied after a change in the modeling framework (e.g., an update in the PIM-to-code transformation due to a change in the target deployment technology). The proposed framework has been implemented and is under evaluation in a real-world MDE tool.

Developing Web applications is a complex and time consuming process that involves different kind of people, ranging from customers to developers. Requirement artefacts play an important role as they are used by these people to perform their daily activities. However, state of the art in requirement management for Web applications disregards valuable features that tend to improve the development process, such as quick validation during elicitation, automatic requirement validation on the final application and useful change management support. To tackle these problems we introduce WebSpec, a requirement artefact for specifying interaction and navigation features in Web applications. We show its use through the development of an example application in the social networking area, and its implementation as an Eclipse plugin.

There is a current trend in the industry to migrate its traditional Web applications to Rich Internet Applications (RIAs). To face this migration, traditional Web methodologies are being extended with new RIA modeling primitives. However, this re-engineering process is being figured out in an ad-hoc manner by introducing directly these new features in the models, crosscutting the old functionality and compromising the readability, reusability and maintainability of the whole system. With the aim of performing this re-engineering process more systematic and less error prone we propose in this paper an approach based on separation of concerns applied to the specific case of WebML.

Model-based approaches for interactive Web applications have neglected vocal interaction. However, ubiquitous multi-device environments call for better support for such modality. In this paper we present a language for logical descriptions of vocal interfaces along with a transformation for deriving corresponding implementations and show an example application. Such results have been integrated into a multi-device authoring environment.

Due to the increasing interest in Web quality, usability and user experience, quality models and frameworks have become a prominent research area as a first step in evaluating them. The ISO 25010/25012 standards were recently issued which specify and evaluate software and data quality requirements. In this work we propose extending the ISO 25010 standard to incorporate new characteristics and concepts into a flexible modeling framework. Particularly, we focus on including information quality, and learnability in use characteristics, and actual usability and user experience concepts into the modeling framework. The resulting models and framework contribute towards a flexible, integrated approach to evaluate Web applications. The operability and particularly the learnability of a real Web application are evaluated using the framework.

Thousands of users are streamlining their Web interactions through user scripts using special

weavers

such as

Greasemonkey

. Thousands of programmers are releasing their scripts in public repositories. Millions of downloads prove the success of this approach. So far, most scripts are just a few lines long. Although the amateurism of this community can partially explain this fact, it can also stem from the doubt about whether larger efforts will pay off. The fact that scripts directly access page structure makes scripts fragile to page upgrades. This brings the nightmare of maintenance, even more daunting considering the leisure-driven characteristic of this community. On these grounds, this work introduces

interfaces for scripting

. Akin to the

JavaScript

programming model,

Scripting Interfaces

are event-based, but rather than being defined in terms of low-level, user-interface events,

Scripting Interfaces

abstract these DOM events into

conceptual events

. Scripts can now subscribe to or notify of

conceptual events

in a similar way to what they did before. So-developed scripts improve their change resilience, portability, readability and easiness to collaborative development of scripts. This is achieved with no paradigm shift: programmers keep using native

JavaScript

mechanisms to handle

conceptual events

.

Users sharing and authoring of Web contents via different Web sites is the main idea of the Web 2.0. However, Web users belong to different communities and follow their own semantics (referred to as local contexts) to represent and interpret Web contents. Therefore, they encounter discrepancies when they have to interpret Web contents authored by different persons. This paper proposes a context-aware interaction approach that helps Web authors annotate Web contents with their local context information, so that it becomes possible for Web browsers to personalize these contents according to different users’ local contexts.

In order to break down the walls that lock-in social data and social networks, new paradigms and architectures must be envisioned. There needs to be a focus on the one hand on distributed architectures — so that users remain owners of their data — and on the other hand on means to semantically-enhance their content — so that it becomes more meaningful and interoperable. In this paper, we detail the anatomy of SMOB, a distributed semantic microblogging framework. In particular, we describe how it achieves the previous objectives using Semantic Web standards (including RDF(S)/OWL, RDFa, SPARQL) and Linked Data principles, as a consequence rethinking the microblogging experience and, more generally, providing Linked Social Data as part of the growing Linking Open Data cloud.

This contribution presents GEMSjax – a web-based metamodeling tool for the collaborative development of domain specific languages. By making use of modern Web 2.0 technologies like Ajax and REST services, the tool allows for simultaneous web browser-based creation/editing of metamodels and model instances, as well as secure remote model access via REST, which enables remote model modification over a simple HTTP-based interface. This paper describes the complex technical challenges we faced and solutions we produced to provide browser-based synchronous model editing. It further explains on the XACML-based access control mechanisms to provide secure remote access to models and model elements. Additionally, we highlight the usefulness of our approach by describing its application in a realistic usage scenario.

Web forms are the main input mechanism for users to supply data to web applications. Users fill out forms in order to, for example, sign up to social network applications or do advanced searches in search-based web applications. This process is highly repetitive and can be optimized by reusing the user’s data across web forms. In this paper, we present a novel framework for domain-independent automatic form filling. The main task is to automatically fill out a correct value for each field in a new form, based on web forms the user has previously filled. The key innovation of our approach is that we are able to extract relevant metadata from the previously filled forms, semantically enrich it, and use it for aligning fields between web forms.

Web-based access to services increasingly moves to location-oriented scenarios, with either the client being mobile and requesting relevant information for the current location, or with a mobile or stationary client accessing a service which provides access to location-based information. The Web currently has no specific support for this kind of service pattern, and many scenarios use proprietary solutions which result in vertical designs with little possibility to share and mix information across various services. This paper describes an architecture for providing access to location-oriented services which is based on the principles of

Representational State Transfer (REST)

and uses a tiling scheme to allow clients to uniformly access location-oriented services. Based on these

Tiled Feeds

, lightweight access to location-oriented services can be implemented in a uniform and scalable way, and by using feeds, established patterns of information aggregation, filtering, and republishing can be easily applied.

Many Web applications provide personalized and adapted services and contents to their users. As these Web applications are becoming increasingly connected, a new interesting challenge in their engineering is to allow the Web applications to exchange, reuse, integrate, interlink, and enrich their data and user models, hence, to allow for user modeling and personalization across application boundaries. In this paper, we present the Grapple User Modeling Framework (GUMF) that facilitates the brokerage of user profile information and user model representations. We show how the existing GUMF is extended with a new method that is based on configurable derivation rules that guide a new knowledge deduction process. Using our method, it is possible not only to integrate data from GUMF dataspaces, but also to incorporate and reuse RDF data published as Linked Data on the Web. Therefore, we introduce the so-called Grapple Derivation Rule (GDR) language as well as the corresponding GDR Engine. Further, we showcase the extended GUMF in the context of a concrete project in the e-learning domain.

The recent proliferation of crowd computing initiatives on the web calls for smarter methodologies and tools to annotate, query and explore repositories. There is the need for scalable techniques able to return also approximate results with respect to a given query as a ranked set of promising alternatives. In this paper we concentrate on annotation and retrieval of software components, exploiting semantic tagging relying on Linked Open Data. We focus on DBpedia and propose a new hybrid methodology to rank resources exploiting: (i) the graph-based nature of the underlying RDF structure, (ii) context independent semantic relations in the graph and (iii) external information sources such as classical search engine results and social tagging systems. We compare our approach with other RDF similarity measures, proving the validity of our algorithm with an extensive evaluation involving real users.

In this paper, we introduce Linkator, an application architecture that exploits semantic annotations for automatically adding links to previously generated web pages. Linkator provides a mechanism for dereferencing these semantic annotations with what it calls semantic links. Automatically adding links to web pages improves the users’ navigation. It connects the visited page with external sources of information that the user can be interested in, but that were not identified as such during the web page design phase. The process of auto-linking encompasses: finding the terms to be linked and finding the destination of the link. Linkator delegates the first stage to external semantic annotation tools and it concentrates on the process of finding a relevant resource to link to. In this paper, a use case is presented that shows how this mechanism can support knowledge workers in finding publications during their navigation on the web.

Smart cards are commonly used for tasks with high security requirements such as digital signatures or online banking. However, systems that Web-enable smart cards often reduce the security and usability characteristics of the original application, e.g., by forcing users to execute privileged code on the local terminal (computer) or by insufficient protection against malware. In this paper we contribute with techniques to generally Web-enable smart cards and to address the risks of malicious attacks. In particular, our contributions are: (i) A single generic proxy to allow a multitude of authorized Web applications to communicate with

existing

smart cards and (ii) two security extensions to mitigate the effects of malware. Overall, we can mitigate the security risks of Web-based smart card transactions and—at the same time—increase the usability for users.

Large amounts of information are posted daily on the Web, such as articles published online by traditional news agencies or blog posts referring to and commenting on various events. Although the users sometimes rely on a small set of trusted sources from which to get their information, they often also want to get a wider overview and glimpse of what is being reported and discussed in the news and the blogosphere. In this paper, we present an approach for supporting this discovery and exploration process by exploiting term clouds. In particular, we provide an efficient method for dynamically computing the most frequently appearing terms in the posts of monitored online sources, for time intervals specified at query time, without the need to archive the actual published content. An experimental evaluation on a large-scale real-world set of blogs demonstrates the accuracy and the efficiency of the proposed method in terms of computational time and memory requirements.

This paper reports the development of a RESTful Web service platform at Nokia Research Center for building Mixed Reality services. The platform serves geo-spatially oriented multimedia content, geo-data like street-view panoramas, building outlines, 3D objects and point cloud models. It further provides support for identity management and social networks, as well as for aggregating content from third party content repositories. The implemented system is evaluated on architecture qualities like support for evolution and mobile clients. The paper outlines our approach for developing RESTful Web services from requirements to an implemented service, and presents the experiences and insights gained during the platform development, including the benefits and challenges identified from adhering to the Resource Oriented Architecture style.

This paper presents WebRatio BPM, an Eclipse-based tool that supports the design and deployment of business processes as Web applications. The tool applies Model Driven Engineering techniques to complex, multi-actor business processes, mixing tasks executed by humans and by machines, and produces a Web application running prototype that implements the specified process. Business processes are described through the standard BPMN notation, extended with information on task assignment, escalation policies, activity semantics, and typed dataflows, to enable a two-step generative approach: first the Process Model is automatically transformed into a Web Application Model in the WebML notation, which seamlessly expresses both human- and machine-executable tasks; secondly, the Application Model is fed to an automatic transformation capable of producing the running code. The tool provides various features that increase the productivity and the quality of the resulting application: one-click generation of a running prototype of the process from the BPMN model; fine-grained refinement of the resulting application; support of continuous evolution of the application design after requirements changes (both at business process and at application levels).

Integrating software applications is a challenging, but often very necessary, activity for businesses to perform. Even when applications are designed to fit together, creating an integrated solution often requires a significant effort in terms of configuration, fine tuning or resolving deployment conflicts. This is often the case when the original applications have been designed in isolation. This paper presents a visual method allowing an application designer to quickly integrate two products, taking the output of a sequence of steps on the first product and using that as input of a sequence of steps on the second product. The tool achieves this by: (1) copying UI components from the underlying applications user interface; (2) capturing user interaction using recording technology, rather than by relying on the underlying data sources; and (3) exposing the important business transactions that the existing application enables as macros which can then be used to integrate products together.

There are insufficient examples available of how customization is realized in multi-tenant web applications, whereas developers are looking for examples and patterns as inspiration for their own web applications. This paper presents an overview of how variability realization techniques from the software product line world can be applied to realize customization when building multi-tenant web applications. The paper addresses this issue by providing a catalogue of customization realization techniques, which are illustrated using occurrences of customization in two practical innovative cases from the library sector. The catalogue and its examples assist developers in evaluating and selecting customization realization techniques for their multi-tenant web application.

The value of crowdsourcing, arising from an instant access to a scalable expert network on-line, has been demonstrated by many success stories, such as GoldCorp, Netflix, and TopCoder. For enterprises, crowdsourcing promises significant cost-savings, quicker task completion times, and formation of expert communities (both within and outside the enterprise). Many aspects of the vision of enterprise crowdsourcing are under vigorous refinement. The reasons for this lack of progress, beyond the isolated and purpose-specific crowdsourcing efforts, are manifold. In this paper, we present our experience in deploying an enterprise crowdsourcing service in the IT Inventory Management domain. We focus on the technical and sociological challenges of creating enterprise crowdsourcing service that are general-purpose, and that extend beyond mere specific-purpose, run-once prototypes. Such systems are deployed to the extent that they become an integrated part of business processes. Only when such degree of integration is achieved, the enteprises can fully adopt crowdsourcing and reap its benefits. We discuss the challenges in creating and deploying the enterprise crowdsourcing platform, and articulate current technical, governance and sociological issues towards defining a research agenda.

People involved in outsourcing services work through

collaboration, conversations and ad-hoc

activities and often follow guidelines that are described in best practice frameworks. There are two main issues hindering the efficient support of best practice frameworks in outsourcing services: lack of

visibility

into how the work is done that prevents

repeatability

, and conducting best practice processes that are

ad-hoc

and

dynamically defined and refined

. In this paper, we present Business Conversation Manager (BCM) that enables and drives business conversations among people around best practice processes. It supports the dynamic definition and refinement of a process in a collaborative and flexible manner. The ad-hoc processes are backed with a semi-formal process model that maintains the model of interactions and an execution engine. We present the implementation of a prototype BCM and its application in outsourcing services. It supports making processes from best practices among people more transparent, repeatable and traceable.

Modern Web applications that embed sophisticated user interfaces and business logic have rendered the original interaction paradigm of the Web obsolete. In previous work, we have advocated a paradigm shift from static content pages that are browsed by hyperlinks to a state-based model where back and forward navigation is replaced by a full-fledged interactive application paradigm, featuring undo and redo capabilities, with support for exception management policies and transactional properties. In this demonstration, we present an editor and code generator designed to build applications based on our approach.

Nowadays, Web encyclopedias suffer from a high bounce rate. Typically, users come to an encyclopaedia from a search engine and upon reading the first page on the site they leave it immediately thereafter. To tackle this problem in systems such as Web shops additional browsing tools for easy finding of related content are provided. In this paper we present a tool that links related content in an encyclopaedia in a usable and visually appealing manner. The tool combines two promising approaches – tag clouds and historic search queries – into a new single one. Hence, each document in the system is enriched with a tag cloud containing collections of related concepts populated from historic search queries. A preliminary implementation of the tool is already provided within a Web encyclopaedia called Austria-Forum.

This paper shows a novel tool, GAmera, the first mutant generation tool for testing Web Service compositions written in the WS-BPEL language. After several improvements and the development of a graphical interface, we consider GAmera to be a mature tool that implements an optimization technique to reduce the number of generated mutants without significant loss of testing effectiveness. A genetic algorithm is used for generating and selecting a subset of high-quality mutants. This selection reduces the computational cost of mutation testing. The subset of mutants generated with this tool allows the user to improve the quality of the initial test suite.

This demo paper introduces SMOB, an open, distributed and semantic microblogging system using Semantic Web technologies (RDF(S)/OWL and SPARQL) and Linked Data principles. We present its ontology stack and related annotations, its distributed architecture, and its interlinking capabilities with the Linking Open Data cloud.

In this paper we present the ServFace Builder, an authoring tool that enables people without programming skills to design and create service-based interactive applications in a graphical manner. The tool exploits the concept of service annotations for developing multi-page interactive applications targeting various platforms and devices.

Web applications that are highly dynamic and interactive on the client side are becoming increasingly popular. As with any other type of applications, reuse offers considerable benefits. In this paper we present our first results on extracting easily reusable web user-interface controls. We have developed a tool called Firecrow that facilitates the extraction of reusable client side controls by dynamically analyzing a series of interactions, carried out by the developer, in order to extract the source code and the resources necessary for the reuse of the desired web user-interface control.

In a mobile setting, users use, handle and search for online information in a different way. Two features typically desired by mobile users are tailored information delivery and context awareness. In this paper, we elaborate a demo application that is built upon the existing SCOUT framework, which supports mobile, context-aware applications. The application illustrates the use of intrinsic mobile features, such as context- and environment-awareness, and combines them with the use of Semantic Web technologies to integrate and tailor knowledge present in distributed data sources.

The web accelerated the way people collaborate globally distributed. With Google Wave, a rich and extensible real-time collaboration platform is becoming available to a large audience. Google implements an operational transformation (OT) approach to resolve conflicting concurrent edits. However, the OT interface is not available for developers of Wave feature extensions, such as collaborative model editors. Therefore, programmers have to implement their own conflict management solution.

This paper presents our lightweight library called syncro. Syncro addresses the problem in a general fashion and can be used for Wave gadget programming as well as for other collaboration platforms that need to maintain a common distributed state.

Rich Internet Applications (RIAs) have recently appeared in the Internet market offering a rich and efficient User Interface similar to desktop applications. However, these applications are rather complex and their development requires design and implementation tasks that are time-consuming and error-prone. In this paper, we present a tool called OIDE (OOH4RIA Integrated Development Enviroment) aimed at accelerating the RIAs development through the OOH4RIA approach which establishes a RIA-specific model-driven process.

Changes in usage patterns of mobile services are continuously influenced by the enhanced features of mobile devices and software applications. Current cross-platform frameworks that allow the implementation of advanced mobile applications have triggered recent developments in relation to end-user mobile services and mobile mashups creation. Inspired by these latest developments, this paper presents our current development related to a cross-platform software system that enables the creation of mobile mashups within an end-user programming environment.

There have been some efforts to take advantages of the Web for the IPTV domain to overcome its limitations. As users become the center of the contents creation and distribution, motivating user participation is the key to the success of the Web-based IPTV. In this paper, we propose a new IPTV framework, called a blog-centered IPTV, where personal blogs are the first-class entities that represent user interests in IPTV contents. An IPTV blog provides a user with a set of interfaces for finding, accessing and organizing IPTV contents based on their needs, and becomes an active entity to join communities and to participate in making community contents evolved. We have implemented a prototype of the blog-centered IPTV, and showed that users can easily find and access their desired contents and successfully build community-based contents.

Effective access to information on the Web requires constant improvement in existing search, navigation and visualization approaches due to the size, complexity and dynamic nature of the web information space. We combine and extend personalization approaches, faceted browsers, graph-based visualization and tree-based history visualization in order to provide users with advanced information exploration and discovery capabilities. We present our personalized exploratory browser Factic as a unique client-side tool for effective Semantic Web exploration.

WS-BPEL eases programming in the large by composing web services, but poses new challenges to classical white-box testing techniques. These have to be updated to take context into account and cope with its specific instructions for web service management. Takuan is an open-source system that dynamically generates invariants reflecting the internal logic of a WS-BPEL composition. After several improvements and the development of a graphical interface, we consider Takuan to be a mature tool that can help find both bugs in the WS-BPEL composition and missing test cases in the test suite.