Identification of Design Principles

This report identifies those design principles for a (possibly new) query and transformation language for the Web supporting inference that are considered essential. Based upon these design principles an initial strawman is selected. Scenarios for querying the Semantic Web illustrate the design principles and their reflection in the initial strawman, i.e., a first draft of the query language to be designed and implemented by the REWERSE working group I4

Design and implementation of a filter engine for semantic web documents

This report describes our project that addresses the challenge of changes in the semantic web. Some studies have already been done for the so-called adaptive semantic web, such as applying inferring rules. In this study, we apply the technology of Event Notification System (ENS). Treating changes as events, we developed a notification system for such events

EquiX---A Search and Query Language for XML

EquiX is a search language for XML that combines the power of querying with the simplicity of searching. Requirements for such languages are discussed and it is shown that EquiX meets the necessary criteria. Both a graphical abstract syntax and a formal concrete syntax are presented for EquiX queries. In addition, the semantics is defined and an evaluation algorithm is presented. The evaluation algorithm is polynomial under combined complexity. EquiX combines pattern matching, quantification and logical expressions to query both the data and meta-data of XML documents. The result of a query in EquiX is a set of XML documents. A DTD describing the result documents is derived automatically from the query.Comment: technical report of Hebrew University Jerusalem Israe

Federation views as a basis for querying and updating database federations

This paper addresses the problem of how to query and update so-called database federations. A database federation provides for tight coupling of a collection of heterogeneous component databases into a global integrated system. This problem of querying and updating a database federation is tackled by describing a logical architecture and a general semantic framework for precise specification of such database federations, with the aim to provide a basis for implementing a federation by means of relational database views. Our approach to database federations is based on the UML/OCL data model, and aims at the integration of the underlying database schemas of the component legacy systems to a separate, newly defined integrated database schema. One of the central notions in database modelling and in constraint specifications is the notion of a database view, which closely corresponds to the notion of derived class in UML. We will employ OCL (version 2.0) and the notion of derived class as a means to treat (inter-)database constraints and database views in a federated context. Our approach to coupling component databases into a global, integrated system is based on mediation. The first objective of our paper is to demonstrate that our particular mediating system integrates component schemas without loss of constraint information. The second objective is to show that the concept of relational database view provides a sound basis for actual implementation of database federations, both for querying and updating purposes.

DataHub: Collaborative Data Science & Dataset Version Management at Scale

Relational databases have limited support for data collaboration, where teams collaboratively curate and analyze large datasets. Inspired by software version control systems like git, we propose (a) a dataset version control system, giving users the ability to create, branch, merge, difference and search large, divergent collections of datasets, and (b) a platform, DataHub, that gives users the ability to perform collaborative data analysis building on this version control system. We outline the challenges in providing dataset version control at scale.Comment: 7 page

The XML Query Language Xcerpt: Design Principles, Examples, and Semantics

Most query and transformation languages developed since the mid 90es for XML and semistructured data—e.g. XQuery [1], the precursors of XQuery [2], and XSLT [3]—build upon a path-oriented node selection: A node in a data item is specified in terms of a root-to-node path in the manner of the file selection languages of operating systems. Constructs inspired from the regular expression constructs , +, ?, and “wildcards” give rise to a flexible node retrieval from incompletely specified data items. This paper further introduces into Xcerpt, a query and transformation language further developing an alternative approach to querying XML and semistructured data first introduced with the language UnQL [4]. A metaphor for this approach views queries as patterns, answers as data items matching the queries. Formally, an answer to a query is defined as a simulation [5] of an instance of the query in a data item