CXQuery: A novel XML query language

XML is becoming the data exchange standard on the Internet. Previously proposed XML query languages, such as XQuery, Quilt, YALT, Lorel, and XML-QL, lack schema definition of the query result; therefore, they are limited for defining views, integrating data, updating, and further querying, all of which are often needed in e-Business applications. We propose a novel XML query language called CXQuery, which defines the schema of the query results explicitly and can easily define views, and integrate, update, and query XML data. In addition, CXQuery can express spatial and spatio-temporal queries using a constraint-based querying approach

A performant XQuery to SQL translator

We describe a largely complete and efficient XQuery to SQL translation for XML publishing. Our translation supports the entire XQuery language, except for functions, if statements and upwards navigation axes. The system has three important properties. First, it preserves the correct XQuery semantics. This is accomplished by first translating XQuery into core-XQuery, using a complete XQuery implementation, Galax. Second, we optimize the resulting SQL queries. We develop a comprehensive framework for optimizing the XQuery to SQL translation, which is effective for a wide range of XQuery workloads. Third, our translation is platform independent. Our system achieves high degree of efficiency on a wide range of relational systems. This paper reports an extensive experimental validation on several XQuery workloads, using MySQL, PostgreSQL, and SQL Server, and compares this approach with five native XQuery engines: Galax (the newer, optimized version), Saxon, QizOpen, IMDB and Quexo

Staircase Join: Teach a Relational DBMS to Watch its (Axis) Steps

Relational query processors derive much of their effectiveness from the awareness of specific table properties like sort order, size, or absence of duplicate tuples. This text applies (and adapts) this successful principle to database-supported XML and XPath processing: the relational system is made tree aware, i.e., tree properties like subtree size, intersection of paths, inclusion or disjointness of subtrees are made explicit. We propose a local change to the database kernel, the staircase join, which encapsulates the necessary tree knowledge needed to improve XPath performance. Staircase join operates on an XML encoding which makes this knowledge available at the cost of simple integer operations (e.g., +, <=). We finally report on quite promising experiments with a staircase join enhanced main-memory database kernel

Four Lessons in Versatility or How Query Languages Adapt to the Web

Exposing not only human-centered information, but machine-processable data on the Web is one of the commonalities of recent Web trends. It has enabled a new kind of applications and businesses where the data is used in ways not foreseen by the data providers. Yet this exposition has fractured the Web into islands of data, each in different Web formats: Some providers choose XML, others RDF, again others JSON or OWL, for their data, even in similar domains. This fracturing stifles innovation as application builders have to cope not only with one Web stack (e.g., XML technology) but with several ones, each of considerable complexity. With Xcerpt we have developed a rule- and pattern based query language that aims to give shield application builders from much of this complexity: In a single query language XML and RDF data can be accessed, processed, combined, and re-published. Though the need for combined access to XML and RDF data has been recognized in previous work (including the W3C’s GRDDL), our approach differs in four main aspects: (1) We provide a single language (rather than two separate or embedded languages), thus minimizing the conceptual overhead of dealing with disparate data formats. (2) Both the declarative (logic-based) and the operational semantics are unified in that they apply for querying XML and RDF in the same way. (3) We show that the resulting query language can be implemented reusing traditional database technology, if desirable. Nevertheless, we also give a unified evaluation approach based on interval labelings of graphs that is at least as fast as existing approaches for tree-shaped XML data, yet provides linear time and space querying also for many RDF graphs. We believe that Web query languages are the right tool for declarative data access in Web applications and that Xcerpt is a significant step towards a more convenient, yet highly efficient data access in a “Web of Data”

Intuitionistic fuzzy XML query matching and rewriting

With the emergence of XML as a standard for data representation, particularly on the web, the need for intelligent query languages that can operate on XML documents with structural heterogeneity has recently gained a lot of popularity. Traditional Information Retrieval and Database approaches have limitations when dealing with such scenarios. Therefore, fuzzy (flexible) approaches have become the predominant. In this thesis, we propose a new approach for approximate XML query matching and rewriting which aims at achieving soft matching of XML queries with XML data sources following different schemas. Unlike traditional querying approaches, which require exact matching, the proposed approach makes use of Intuitionistic Fuzzy Trees to achieve approximate (soft) query matching. Through this new approach, not only the exact answer of a query, but also approximate answers are retrieved. Furthermore, partial results can be obtained from multiple data sources and merged together to produce a single answer to a query. The proposed approach introduced a new tree similarity measure that considers the minimum and maximum degrees of similarity/inclusion of trees that are based on arc matching. New techniques for soft node and arc matching were presented for matching queries against data sources with highly varied structures. A prototype was developed to test the proposed ideas and it proved the ability to achieve approximate matching for pattern queries with a number of XML schemas and rewrite the original query so that it obtain results from the underlying data sources. This has been achieved through several novel algorithms which were tested and proved efficiency and low CPU/Memory cost even for big number of data sources

The XML benchmark project

With standardization efforts of a query language for XML documents drawing to a close, researchers and users increasingly focus their attention on the database technology that has to deliver on the new challenges that the sheer amount of XML documents produced by applications pose to data management: validation, performance evaluation and optimization of XML query processors are the upcoming issues. Following a long tradition in database research, the XML Store Benchmark Project provides a framework to assess an XML database's abilities to cope with a broad spectrum of different queries, typically posed in real-world application scenarios. The benchmark is intended to help both implementors and users to compare XML databases independent of their own, specific application scenario. To this end, the benchmark offers a set queries each of which is intended to challenge a particular primitive of the query processor or storage engine. The overall workload we propose consists of a scalable document database and a concise, yet comprehensive set of queries, which covers the major aspects of query processing. The queries' challenges range from stressing the textual character of the document to data analysis queries, but include also typical ad-hoc queries. We complement our research with results obtained from running the benchmark on our XML database platform. They are intended to give a first baseline, illustrating the state of the art

Interactive visualization of business processes

Today’s Process-Aware Information Systems (PAIS) logs huge amount of data. The data contains a set of activities that are actual executed with in a business process. For example place a request for unemployment claim or pay compensation. This is a starting point for doing the analysis of a business process using Process Mining techniques. In Process Mining, one technique named LogOnMapReplay, which is dynamically visualizing the executed business processes by producing a process movie. This tool is a prototype that’s why it comes along with various limitations and missing functionalities. This report describes the steps taken to overcome the limitations of the tool. It also describes design and implementation of various functionalities developed on LogOnMapReplay tool. This report also describes an evaluation conducted on UWV unemployment business process to find the usefulness and intuitiveness of the tool