The in-depth consideration of security aspects in modern web infrastructures has become essential to stay competitive. In this context, continuous authentication is a promising approach to prevent the misuse of digital identities. To this end, machine learning (ML) models are well suited to analyze user behavior and to detect anomalies, due to their ability to identify complex patterns and trends that usually cannot be reflected by static rule-based approaches. However, the training of powerful ML models requires large amounts of data, which are often not available within a single organization. Consequently, a federated training of these models by cooperating organizations offers a promising solution, but leads to concerns about coordination, regulations, and quality assurance. To tackle these challenges, we present an approach that combines three research areas: (1) the establishment of continuous user authentication based on (2) a ML model trained by an organized peer-to-peer federation involving different organizations that is underpinned by (3) federated data governance ensuring regulatory compliance and quality of resulting artefacts.

Abstract Much data on the web is available in hidden databases. Users browse their contents by sending search queries to form-based interfaces or APIs. Yet, hidden databases just return the top-k result entries and limit the number of queries per time interval. Such access restrictions constrict those tasks that require many/specific queries or need to access many/all data entries. For a temporary solution, an unrestricted local snapshot can be created by crawling the hidden database. Yet, keeping the snapshot permanently consistent is challenging due to the access restrictions of its origin. In this paper, we propose a replication approach providing permanent unrestricted access to the local copy of a hidden database with dynamic changes. To this end, we present an algorithm to effectively crawl hidden databases that outperforms the state of the art. Furthermore, we propose a new way to continuously control the consistency of the replicated database in an efficient manner. We also introduce the cloud-based architecture of a replication service for hidden databases. We show the effectiveness of the approach through a variety of reproducible experimental evaluations.

Crowdsourcing in the form of human-based electronic services (people services) provides a powerful way of outsourcing tasks to a large crowd of remote workers over the Internet. Research has shown that multiple redundant results delivered by different workers can be aggregated in order to achieve a reliable result. However, basic implementations of this approach are rather inefficient as they multiply the effort for task execution and are not able to guarantee a certain quality level. In this paper, we are addressing these challenges by elaborating on a statistical approach for quality management of people services which we had previously proposed. The approach combines elements of statistical quality management with dynamic group decisions. We present a comprehensive statistical model that enhances our original work and makes it more transparent. We also provide an extendible toolkit that implements our model and facilitates its application to real-time experiments as well as to simulations. A quantitative analysis based on an optical character recognition (OCR) scenario confirms the efficiency and reach of our model.

Service-oriented computing is meant to support loose relationships between organisations: Collaboration procedures on the application-level translate to interaction processes via Web Services. Service composition deals with the specification and enforcent of such processes. Its main focus is on service orchestration where workflow managent is utilised for proactive coordination. In such an approach, coordination process and interaction logic are usually captured in the same workflow - which leads to deficiencies in recognising the possible impact of operational coordination on the interaction logic. In this paper, we claim that the choice of coordination alternatives impacts the quality of the composed service and has to be customised to each specific service case. As a consequence, we outline a solution that is based on service interaction patterns where the paradigms of patterns and idioms are applied to interaction procedures and orchestration processes. This allows studying a) reusable interaction patterns typical for service relationships and b) for each pattern a range of possible coordination idioms. Finally, we sketch a technique that refines the service logic based on analysis of its interaction patterns and utilisation of suitable coordination idioms selected by rules in terms of changing service context.

The line of research explored in this paper derives from an approach to process modelling and management that explicitly targets the peculiarities and dynamics of business-to-business interaction. In the model we propose, the upfront specification of the interaction logic of a company can be limited to partially specified processes and basic interaction rules. Specific information is then gathered from the observation of actual instances of business interaction, and used to refine and extend the initial model. In addition to the enforcement of explicit business requirement, the goal is to capture and leverage implicit operational knowledge.

For the majority of front-end e-business systems, the assumption of a coherent and homogeneous set of interfaces is highly unrealistic. Problems start in the back-end, with systems characterised by a heterogeneous mix of applications and business processes. Integration can be complex and expensive, as systems evolve more in accordance with business needs than with technical architectures. E-business systems are faced with the challenge to give a coherent image of a diversified reality. Web services make business interfaces more efficient, but effectiveness is a business requirement of at least comparable importance. We propose a technique for automatic reconciliation of the Web service interfaces involved in inter-organisational business processes. The working assumption is that the Web service front-end of each company is represented by a set of WSDL and WSCL interfaces. The result of our reconciliation method is a common interface that all the parties can effectively enforce. Indications are also given on ways to adapt individual interfaces to the common one. The technique was embodied in a prototype that we also present.