12403884
Preserving mapping consistency under schema changes
Abstract.In dynamic environments like the Web, data sources may change not only their data but also their schemas, their semantics, and their query capabilities. When a mapping is left inconsistent by a schema change, it has to be detected and updated. We present a novel framework and a tool (ToMAS) for automatically adapting (rewriting) mappings as schemas evolve. Our approach considers not only local changes to a schema but also changes that may affect and transform many components of a schema. Our algorithm detects mappings affected by structural or constraint changes and generates all the rewritings that are consistent with the semantics of the changed schemas. Our approach explicitly models mapping choices made by a user and maintains these choices, whenever possible, as the schemas and mappings evolve. When there is more than one candidate rewriting, the algorithm may rank them based on how close they are to the semantics of the existing mappings.
1321953
Data-driven understanding and refinement of schema mappings
At the heart of many data-intensive applications is the problem of quickly and accurately transforming data into a new form. Database researchers have long advocated the use of declarative queries for this process. Yet tools for creating, managing and understanding the complex queries necessary for data transformation are still too primitive to permit widespread adoption of this approach. We present a new framework that uses data examples as the basis for understanding and refining declarative schema mappings. We identify a small set of intuitive operators for manipulating examples. These operators permit a user to follow and refine an example by walking through a data source. We show that our operators are powerful enough both to identify a large class of schema mappings and to distinguish effectively between alternative schema mappings. These operators permit a user to quickly and intuitively build and refine complex data transformation queries that map one data source into another.
16826457
Creating Nested Mappings with Clio
Schema mappings play a central role in many data integration and data exchange scenarios. In those applications, users need to quickly and correctly specify how data represented in one format is converted into a different format. Clio (L. Popa et al., 2002) is a joint research project between IBM and the University of Toronto studying the creation, maintenance, and use of schema mappings. There have always been two goals in our work in Clio: 1) the automatic creation of logical assertions that capture the way one or more source schemas are mapped into a target schema, and 2) the generation of transformation queries or programs that transform a source data instance into a target data instance.
473917
Leveraging data and structure in ontology integration
There is a great deal of research on ontology integration which makes use of rich logical constraints to reason about the structural and logical alignment of ontologies. There is also considerable work on matching data instances from heterogeneous schema or ontologies. However, little work exploits the fact that ontologies include both data and structure. We aim to close this gap by presenting a new algorithm (ILIADS) that tightly integrates both data matching and logical reasoning to achieve better matching of ontologies. We evaluate our algorithm on a set of 30 pairs of OWL Lite ontologies with the schema and data matchings found by human reviewers. We compare against two systems - the ontology matching tool FCA-merge [28] and the schema matching tool COMA++ [1]. ILIADS shows an average improvement of 25% in quality over FCA-merge and a 11% improvement in recall over COMA++.
40383321
Schema Mapping as Query Discovery
5593182
Representing and querying data transformations
Modern information systems often store data that has been transformed and integrated from a variety of sources. This integration may obscure the original source semantics of data items. For many tasks, it is important to be able to determine not only where data items originated, but also why they appear in the integration as they do and through what transformation they were derived. This problem is known as data provenance. In this work, we consider data provenance at the schema and mapping level. In particular, we consider how to answer questions such as "what schema elements in the source(s) contributed to this value", or "through what transformations or mappings was this value derived?" Towards this end, we elevate schemas and mappings to first-class citizens that are stored in a repository and are associated with the actual data values. An extended query language, called MXQL, is also developed that allows meta-data to be queried as regular data and we describe its implementation scenario.
18318781
Schema Discovery
Structured data is distinguished from unstructured data by the presence of a schema describing the logical structure and semantics of the data. The schema is th e means through which we understand and query the underlying data. The schema permits the more sophi ticated structured queries that are not possible over schema-less data. Most systems assume that th e schema is predefined and is an accurate reflection of the data. This assumption is often not valid in n etworked databases that may contain data originating from many sources and may not be valid within leg acy databases where the semantics of data have evolved over time. As a result, querying and tasks that d epend on structured queries (including data integration and schema mapping) may not be effective. I n this paper, we consider the problem of discovering schemas from data. We focus on discovering prop erties of data that can be exploited in querying and transforming data. Finally, we very briefly con sider the suitability of mining approaches to the task of schema discovery.
207156342
How to make secure email easier to use
Cryptographically protected email has a justly deserved reputation of being difficult to use. Based on an analysis of the PEM, PGP and S/MIME standards and a survey of 470 merchants who sell products on Amazon.com, we argue that the vast majority of Internet users can start enjoying digitally signed email today. We present suggestions for the use of digitally signed mail in e-commerce and simple modifications to webmail systems that would significantly increase integrity, privacy and authorship guarantees that those systems make. We then show how to use the S/MIME standard to extend such protections Internet-wide. Finally, we argue that software vendors must make minor changes to the way that mail clients store email before unsophisticated users can safely handle mail that is sealed with encryption.
14511628
Interactive Simultaneous Editing of Multiple Text Regions
Simultaneous editing is a new method for automating repetitive text editing. After describing a set of regions to edit (the records), the user can edit any one record and see equivalent edits applied simultaneously to all other records. The essence of simultaneous editing is generalizing the user’s selection in one record to equivalent selections in the other records. We describe a generalization method that is fast (suitable for interactive use), domain-specific (capable of using high-level knowledge such as Java and HTML syntax), and under user control (generalizations can be corrected or overridden). Simultaneous editing is useful for source code editing, HTML editing, and scripting, as well as many other applications.
5731309
Synchronizing clipboards of multiple computers
This paper describes a new technique for transferring data between computers, the synchronized clipboard. Multiple computers can share a synchronized clipboard for all clipboard operations, so that data copied to the clipboard from one computer, using the standard Copy command, can be pasted directly on another computer using the standard Paste command. Synchronized clipboards are well-suited for a single user moving data among several computers in close proximity. We describe an implementation of synchronized clipboards that works across a wide range of existing systems, including 3Com PalmPilots, Microsoft Windows PCs, Unix workstations, and other Java-capable platforms. Our implementation adds no noticeable overhead to local copy and paste operations.
914575
Building a speech interface to a medical diagnostic system
A description is given of the design of an interface for QMR-DT, an evolving decision-theoretic version of Quick Medical Reference, which performs diagnostic reasoning about diseases in internal medicine. QMR-DT encompasses the part of QMR's functionality that provides differential diagnoses for a set of patient characteristics, but it uses a different algorithm to compute diagnoses. The work described includes two programs that integrate off-the-shelf speech technology with programs that manipulate medical terminology. The term identifier program uses an isolated-word, speaker-dependent speech product to provide an interface for entering medical findings into QMR-DT. Frame browser is an auxiliary program used by the developers of term identifier to examine frame structures. Frame browser was also used to experiment with a continuous-speech system.<<ETX>>