On the basis of regular tree grammars, we present a formal framework for XML schema languages. This framework helps to describe, compare, and implement such schema languages in a rigorous manner. Our main results are as follows: (1) a simple framework to study three classes of tree languages (local, single-type, and regular); (2) classification and comparison of schema languages (DTD, W3C XML Schema, and RELAX NG) based on these classes; (3) efficient document validation algorithms for these classes; and (4) other grammatical concepts and advanced validation algorithms relevant to an XML model (e.g., binarization, derivative-based validation).

Abstract-Web services are considered to be a potential silver bullet for the envisioned Service Oriented Architecture, in which loosely coupled software components are published, located, and executed as integral parts of distributed applications. The main research focus of Web services is to achieve the interoperability between distributed and heterogeneous applications. Therefore, flexible composition of Web services to fulfill the given challenging requirements is one of the most important objectives in this research field. However, until now, service composition has been largely an error-prone and tedious process. Furthermore, as the number of available Web services increases, finding the right Web services to satisfy the given goal becomes intractable. In this paper, toward these issues, we propose an AI planning-based framework that enables the automatic composition of Web services, and explore the following issues. First, we formulate the Web service composition problem in terms of AI planning and network optimization problems to investigate its complexity in detail. Second, we analyze publicly available Web service sets using network analysis techniques. Third, we develop a novel Web service benchmark tool called WSBen. Fourth, we develop a novel AI planning-based heuristic Web service composition algorithm named WSPR. Finally, we conduct extensive experiments to verify WSPR against state-of-the-art AI planners. It is our hope that both WSPR and WSBen will provide useful insights for researchers to develop Web service discovery and composition algorithms, and software.

An extensive bibliometric study on the db community using the collaboration network constructed from DBLP data is presented. Among many, we have found that (1) the average distance of all db scholars in the network has been stabilized to about 6 for the last 15 years, coinciding with the so-called six degrees of separation phenomenon; (2) In sync with Lotka's law on the frequency of publications, the db community also shows that a few number of scholars publish a large number of papers, while the majority of authors publish a small number of papers (i.e., following the power-law with exponent about -2); and (3) with the increasing demand to publish more, scholars collaborate more often than before (i.e., 3.93 collaborators per scholar and with steadily increasing clustering coefficients).

In this paper, we consider the problem of ambiguous author names in bibliographic citations, and comparatively study alternative approaches to identify and correct such name variants (e.g., "Vannevar Bush" and "V. Vush"). Our study is based on a scalable two-step framework, where step 1 is to substantially reduce the number of candidates via blocking, and step 2 is to measure the distance of two names via coauthor information. Combining four blocking methods and seven distance measures on four data sets, we present extensive experimental results, and identify combinations that are scalable and effective to disambiguate author names in citations.

As XML [5] is emerging as the data format of the internet era, there is an substantial increase of the amount of data in XML format. To better describe such XML data structures and constraints, several XML schema languages have been proposed. In this paper, we present a comparative analysis of six noteworthy XML schema languages.