Catálogo de publicaciones - libros

The wide-spread adoption of process-aware information systems has resulted in a bulk of computerized information about real-world processes. This data can be utilized for process performance analysis as well as for process improvement. In this context process mining offers promising perspectives. So far, existing mining techniques have been applied to operational processes, i.e., knowledge is extracted from execution logs (process discovery), or execution logs are compared with some a-priori process model (conformance checking). However, execution logs only constitute one kind of data gathered during process enactment. In particular, adaptive processes provide additional information about process changes (e.g., ad-hoc changes of single process instances) which can be used to enable organizational learning. In this paper we present an approach for mining change logs in adaptive process management systems. The change process discovered through process mining provides an aggregated overview of all changes that happened so far. This, in turn, can serve as basis for all kinds of process improvement actions, e.g., it may trigger process redesign or better control mechanisms.

The number of services on the web is growing every day and finding useful and efficient ranking methods for services has become an important issue in modern web applications. In this paper we present a link-based importance model and efficient algorithms for distributed services collaborating through service calls. We adapt the PageRank algorithm and define a service importance that reflects its activity and its contribution to the quality of other services.

In this paper we consider information exchange via the Web to be an information market. The notion of quality plays an important role on this information market. We present a model of quality and discuss how this model can be operationalized.

This leads us to quality measurement, interpretation of measurements and the associated accuracy. An illustration in the form of a basic quality assessment system is presented.

We consider a problem of Web service resource allocation in an economic setting. We assume that different requestors have different valuations for services and a deadline for executing a service, after which it is no longer required. We formally show an optimal offline allocation that maximizes the total welfare, denoted as the total benefit of the requestors. We then propose a bid-based approach to resource allocation and pricing for Web services. Using a detailed simulation, we analyze its behavior and performance compared to other known algorithms. We empirically show that flexibility in service price benefits both the provider in terms of profit and the requestors in terms of welfare.

Our problem motivation stems from the expanding use of Service-Oriented Architecture (SOA) for outsourcing enterprize activities. While the most common method for pricing a Web service nowadays is a fixed-price policy (with a price of 0 in many cases), A Service-Oriented Architecture will increasingly generate competition among providers, underlying the importance of finding methodologies for pricing Web service execution.

Users preferences heterogeneity in distributed systems often forces resources suppliers to offer customizable-resources in order to fulfill different customer needs. We present in this paper a Feature Logic based approach to customizable-resources description, selection, and composition. In our approach, resources and requests are both specified in a logical framework by feature terms. The feature terms unification technique allows reasoning on these specifications in order to select and possibly compose the resources that are candidate to satisfy a client request.

This paper introduces – a model for securing service-based coordinated systems. The model uses constraints for expressing the application logic of a coordinated system and its required security strategies. Coordination activities are the key concepts used for controlling the execution of participating services. Constraints are specified as pre and post conditions of these coordination activities.

Web services are becoming more and more complex, involving numerous interacting business objects within complex distributed processes. In order to fully explore Web service business opportunities, while ensuring a correct and reliable execution, analyzing and tracking Web services interactions will enable them to be well understood and controlled. The work described in this paper is a contribution to these issues for Web services based process applications.

This article describes a novel way of applying process mining techniques to Web services logs in order to enable “Web service intelligence”. Our work attempts to apply Web service log-based analysis and process mining techniques in order to provide semantical knowledge about the context of and the reasons for discrepancies between process models and related instances.

One method for establishing a trust relationship between two servers in a co-operative information system is to use a mutual attestation protocol based on hardware that implements the Trusted Computing Group’s TPM specification. It has been our experience in developing an eHealth demonstration system that the efficiency of such a protocol was relatively low. This inefficiency was a result of the high number of TPM function calls in response to the large number of protocol messages that must be sent by the end server systems to establish mutual trust between them prior to sending each application message (in our case, a medical record). In order to address this inefficiency, we developed a session-based mutual attestation protocol, where multiple application messages are sent over an interval of time where an established trust relationship holds. Moreover, the protocol partially addresses the security flaw due to the time interval between the time-of-attestation and time-of-use. This paper presents this new protocol, once again utilizing TPM microcontroller hardware, and compares its performance with that of our previous (per record) mutual attestation protocol.

Trust models have been touted to facilitate cooperation among unknown entities. Existing behavior-based trust models typically include a fixed evaluation scheme to derive the trustworthiness of an entity from knowledge about its behavior in previous interactions. This paper in turn proposes a framework for behavior-based trust models for open environments with the following distinctive characteristic. Based on a relational representation of behavior-specific knowledge, we propose a trust-policy algebra allowing for the specification of a wide range of trust-evaluation schemes. A key observation is that the evaluation of the standing of an entity in the network of peers requires centrality indices, and we propose a first-class operator of our algebra for computation of centrality measures. This paper concludes with some preliminary performance experiments that confirm the viability of our approach.

The growing need for information sharing among partnering organizations or members of virtual organizations poses a great security challenge. One of the key aspects of this challenge is deploying intrusion detection systems (IDS) that can operate in heterogeneous, large-scale environments. This is particularly difficult because the different networks involved generally use IDSs that have not been designed to work in a cooperative fashion. This paper presents a model for integrating intrusion detection systems in such environments. The main idea is to build compositions of IDSs that work as unified systems, using a service-oriented architecture (SOA) based on the Web Services technology. The necessary interoperability among the elements of the compositions is achieved through the use of standardized specifications, mainly those developed by IETF, W3C and OASIS . Dynamic compositions are supported through service orchestration. We also describe a prototype implementation of the proposed infrastructure and analyze some results obtained through experimentation with this prototype.