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Pervasive computing environments are nowadays more and more used as a supporting tool for cooperative workflows, e.g., in emergency management. A typical problem in these scenarios is the synthesis of workflows in presence of sets of services (hosted on mobile devices) with constrained behaviors, just before the collaborating team is dropped off in the operation field. In this paper, we propose a technique able to automatically synthesize distributed orchestrators, each one coordinating a service and synchronizing with the other orchestrators, given a target generic workflow to be carried out and a set of behaviorally-constrained services.

The tutorial aims at providing a deep comprehension of the Web service composition problem and automated techniques to tackle it. Web service composition is currently one the most hyped and addressed issue in the service oriented computing. Starting from an analysis of current technologies and standards for Web service composition, the tutorial will lead the attendees to consider formal models at the base of current proposals, and techniques that can be fruitfully considered to address automatic composition synthesis in each of them. More in detail, attendees will consider: (i) basic technologies and standards for Web service invocation and description (SOAP, UDDI, WSDL,...); (ii) advanced technologies and standards for orchestration and inter-organizational process enactment, in particular WS-BPEL and WS-CDL; (iii) models for Web service composition; (iv) formal tools for both data-centric and process-centric synthesis, including query reformulation a'la data integration, transition-systems based formalisms, trace-based formalisms, logics of programs and processes. In particular, we will show how these formal tools can be applied for automatic Web service composition; (v) current state-of-the-art research results in automatic service composition, drawing a comparison and defining a unifying framework

Current information systems are required to deal with more complex data with respect to traditional relational data. The database community has already proposed abstractions for these kinds of data, in particular in terms of semistructured data models. A semistructured model conceives a database essentially as a finite directed labeled graph whose nodes represent objects, and whose edges represent relationships between objects. In the same way as conjunctive queries form the core of any query language for the relational model, regular path queries (RPQs) and their variants are considered the basic querying mechanisms for semistructured data.Besides the basic task of query answering, i.e., evaluating a query over a database, databases should support other reasoning services related to querying. One of the most important is query containment, i.e., verifying whether for all databases the answer to a query is a subset of the answer to a second query. Another important reasoning service that has received considerable attention in the recent years is view-based query processing, which amounts to processing queries based on a set of materialized views, rather than on the raw data in the database.The goal of this paper is to describe basic results and techniques concerning query containment and view based query processing for the class of two-way regular-path queries (which extend RPQs with the inverse operator). We will demonstrate that the basic services for reasoning about two way regular path queries are decidable, thus showing that the limited form of recursion expressible by these queries does not endanger the decidability of reasoning. Besides the specific results, our methods show the power of two-way automata in reasoning on complex queries.

Source integration is one of the core problems in data warehousing. Two critical factors for the design and maintenance of applications requiring source integration, and in particular data warehouse applications, are conceptual modeling of the domain, and reasoning support over the conceptual representation. We present a novel approach to conceptual modeling for source integration, which allows for suitably modeling the global concepts of the application, the individual information sources, and the constraints among different sources. Our methodological framework relies on the reasoning services associated with the modeling formalism to support an incremental source integration phase within the data warehouse design process.

Class-based languages express knowledge in terms of objects and classes, and have inspired a huge number of formalisms in computer science. Description logics forma family of both class-based and logic-based knowledge representation languages which allow for modeling an application domain in terms of objects, classes and relationships between classes, and for reasoning about them. This paper presents an overview of the research carried out in the last years in description logics, with the main goal of illustrating how these logics provide the foundations for class-based knowledge representation formalisms.

Query answering using views amounts to computing the answer to a query having information only on the extension of a set of views. This problem is relevant in several fields, such as information integration, data warehousing, query optimization, mobile computing, and maintaining physical data independence. We address query answering using views in a context where queries and views are regular path queries, i.e., regular expressions that denote the pairs of objects in the database connected by a matching path. Regular path queries are the basic query mechanism when the database is conceived as a graph, such as in semistructured data and data on the Web. We study algorithms for answering regular path queries using views under different assumptions, namely, closed and open domain, and sound, complete, and exact information on view extensions. We characterize data, expression, and combined complexity of the problem, showing that the proposed algorithms are essentially optimal. Our results are the first to exhibit decidability in cases where the language for expressing the query and the views allows for recursion.