Biomedical questions are often complex and address multiple topics simultaneously. Answering them requires the comprehensive evaluation of several different types of data. They are often available, but in distributed and heterogeneous data sources; this hampers their global evaluation. We developed a software architecture to create and maintain updated a Genomic and Proteomic Data Warehouse (GPDW), which integrates several of the main of such dispersed data. It uses a modular and multi-level global data schema based on abstraction and generalization of integrated data features. Such a schema eases integration of data sources evolving in data content, structure and number, and assures provenance tracking of all the integrated data. Thanks to the developed software architecture and adopted data schema, the GPDW has been kept updated easily and progressively extended with additional data types and sources; it is publicly usable at http://www.bioinformatics.dei.polimi.it/GPKB/.

Virtual worlds such as Second Life are closed environments that are purposely isolated from the real world and, in particular, from the data and information space provided by the World Wide Web. There is a rising need, however, tocommunicate and exchange data between virtual environments and the outside world, both for commercial applications andfor private convenience.Companies, for example, may want to display price lists, corporate news, and other changing information insideSecond Life, and thus need a method for continually transferring data from their web site into Second Life.In this paper we tackle the problems and difficulties of data exchange between virtual worlds and the real world. We compare different fundamental approaches of realizing communication channels and outline a general method fordesigning interfaces between virtual worlds and real-world data spaces.We discuss implementation issues and demonstrate the effectiveness of our approach with a number of successful prototype implementations.

We propose a novel conception language for exploring the results retrieved by several internet search services (like search engines) that cluster retrieved documents. The goal is to offer users a tool to discover relevant hidden relationships between clustered documents.

This paper describes the architecture and the functionalities of a clustering search engine prototypal system, named Matrioshka, whose peculiarity is the flexibility of the interaction framework on which it is based.

The need of formal verification is a problem that involves all the fields in which sensible data are managed. In this context the verification of data streams became a fundamental task. The purpose of this paper is to present a framework, based on the model checker SPIN, for the verification of data streams.The proposed method uses a linear temporal logic, called TRIO, to describe data constraints and properties. Constraints are automatically translated into Promela, the input language of the model checker SPIN in order to verify them.

XQBE (XQuery By Example) is a visual XML query language which, coherently with the hierarchical XML data model, uses tree-shaped structures to express queries and transformations over XML documents. These structures are annotated to express selection predicates; explicit bindings between the nodes of such structures visualize the input/output mappings.XQuery and XSLT, the standard query and transformation languages for XML, happen to be too complex for most occasional or unskilled users who might need to specify queries, schema mappings, or document transformations, if they are only aware of the basics of the XML data model. The implementation of XQBE allows to generate the XQuery and XSLT translations of the visual queries, assisting the user in several aspects of the interaction (e.g. providing interactive access to schema information); therefore, XQBE provides an integrated environment where users can edit the visual queries and their textual counterparts, executing them on several engines. Alternating among different representations of the same query is valuable for training beginners, as we have experienced in our database courses.

The spreading of XML data in many contexts of modern computing infrastructures and systems causes a pressing need for adequate XML querying capabilities; to address this need, the W3C is proposing XQuery as the standard query language for XML, with a language paradigm and a syntactic flavor comparable to the SQL relational language. XQuery is designed for meeting the requirements of skilled database programmers; its inherent complexity makes the new language unsuited to unskilled users.In this article we present XQBE (XQuery By Example), a visual query language for expressing a large subset of XQuery in a visual form. In designing XQBE, we targeted both unskilled users and expert users wishing to speed up the construction of their queries; we have been inspired by QBE, a relational language initially proposed as an alternative to SQL, which is supported by Microsoft Access. QBE is extremely successful among users who are not computer professionals and do not understand the subtleties of query languages, as well as among professionals who can draft their queries very quickly.According to the hierarchical nature of XML, XQBE's main graphical elements are trees. One or more trees denote the documents assumed as query input, and one tree denotes the document produced by the query. Similar to QBE, trees are annotated so as to express selection predicates, joins, and the passing of information from the input trees to the output tree.This article formally defines the syntax and semantics of XQBE, provides a large set of examples, and presents a prototype implementation.

XQuery, the standard query language for XML, is increasingly popular among computer scientists with a SQL background, since queries in XQuery and SQL require comparable skills to be formulated. However, the number of these experts is limited, and the availability of easier XQuery "dialects" could be extremely valuable. With this motivation in mind, we designed XQBE, a dialect of XQuery inspired by the QBE language (query by example). QBE, initially proposed as an alternative to SQL, has then become popular as the user-friendly query language supported by MS Access. XQBE starts from hierarchical structures, coherent with the hierarchical nature of XML, and uses one or more structures to denote the input documents, and one structure to denote the XML document produced in output. These structures are annotated to express selection predicates; explicit bindings connecting the nodes of these structures visualize the input/output mappings.

Besides being adopted as the new interchange format for the Internet, XML is finding increasing acceptance as a native data repository language. In order to make XML repositories fully equipped with data management capabilities, suitable query and update languages are being developed. However, once the user is allowed to perform updates, it is perceivably necessary to guarantee the correctness of his/her updates, especially if document validity or semantic constraints are violated. We address this problem by exploiting the well-grounded concept of active rules. In this paper, we propose Active XQuery, an active language for XML repositories that is based on a previously defined XQuery update model. In particular, we present the syntax and semantics of our language, aiming at emulating the trigger definition and execution model of SQL3. An active extension of XQuery results in nontrivial problems, related to the need of interleaving updates and triggers. These problems have led us to define an algorithm for update reformulation and to devise a compact semantics. In conclusion, the paper presents an architecture for rapid prototyping, and considers optimization and research issues.

The recent success of XML as a standard to represent semi-structured data, and the increasing amount of available XML data pose new challenges to the data mining community. In this paper we present the XMINE operator, a tool developed to extract XML association rules for XML documents. The operator, based on XPath and inspired by the syntax of XQuery, allows us to express complex mining tasks, compactly and intuitively. XMINE can be used to specify indifferently (and simultaneously) mining tasks both on the content and on the structure of the data, since the distinction in XML is slight.