In this article, we present comparative examples of six XML schema languages (XML-DTD, XML-Schema, RELAX, SOX, Schematron, DSD) and six XML query languages (Lorel, XML-QL, XML-GL, XSLT, XQL and Quilt). Such comparative examples for real-life scenario greatly helped us to understand the languages and to realize the differences among them.

The MITRE Corporation provides technical assistance, system engineering, and acquisition support to U.S. Government agencies and other large organizations. Our customers have high (not always realistic) hopes for XML and related standards.

Sybase ASE provides full XML and XQL support, and Java can be used to easily work with the new features. Here are some examples of how it works.

This list represents the evaluation of XML Query implementation.

Before we go into the details of database tuning, we should make clear that due to ongoing development and tuning of the Tamino engine the performance hints given here are only based on a snapshot of the current situation. Future versions of Tamino may exhibit in parts a different performance profile.

This paper discusses XML query languages and particularly the features or characteristics that the authors believe to be the most important for XML query languages. In order to do this, many example query types are enumerated and an example of each is presented in upto four particular existing query languages. These examples and discussion of them make up the bulk of the paper.

XML-based applications often blur the borders between Internet-, document- and database technology. This is reflected in the architecture of XML-based information systems. Monolithic systems are superseded by systems composed of lightweight, reuseable Java components which are loosely coupled via standardized interfaces. Using the XQL-processor and the PDOM, XML component systems can easily and transparently be augmented with functionality characteristic for database systems: declarative queries and transaction-safe persistence.

The main material in this presentation comes from the paper Comparative analysis of five XML query languages, which compares Lorel, XML-QL, XML-GL, XSL, and XQL, where I only focused on the three bold ones.

The requirements for querying XML documents cover a wide spectrum. Below, we identify a three points on the spectrum based on where the query executes. Later sections discuss characteristics and requirements for each of them.

Several approaches have been proposed, as far as querying RDF metadata is concerned. These approaches can be generally subdivided into two main categories:

Using XQL to query Java and XML data in client/server and distributed environments requires more than the ability to use it on the database server. In this article, I’ll explore using XQL to retrieve results from Sybase ASE from a stand-alone client application, a JDBC client, and an Enterprise JavaBean (EJB) server bean and client. I’ll also examine the surprisingly few methods needed to facilitate this powerful technology.

Mapping data from deeply hierarchical data structures is a challenging and time-consuming task for webMethods developers. The underused and powerful pub.web:queryDocument service can drastically simplify this process.

In this article we will show to to write and install a very simple web application written in the XQuery language. We will also show you how errors are handled, and how you can debug them. Our application uses the servlet extension of Qexo (version 1.7beta2 or later), a free software implementation of XQuery.

XLoc is the XWeb mechanism for referring to a specific unique object on an XWeb site. XLoc is defined as a restriction on XQL. All searching, matching, attribute comparison and methods are removed. What remains are the basic path and subscript mechanisms. An XLoc can be used in conjunction with the protocol, site and port information found in a URL. XLoc is used in a URL after the protocol, site and port information. For example the bold portions of the following URLs are expressed as XLocs.

This document details the W3C Math Working Group's requirements for the XML Query Language effort. Querying MathML requires a pattern language for both element structure and content to return a subtree of the MathML expression tree. The pattern language could be derived from XSL patterns by allowing multiple branches and positions to be specified relative to any node and regular expression matching on content.

XML documents are structured documents - they blur the distinction between data and documents, allowing documents to be treated as data sources, and traditional data sources to be treated as documents. Some XML documents are nothing more than an ASCII representation of data that might traditionally have been stored in a database. Others are documents that contain very little structure beyond the use of headers and tables.

W3C XML Query presentation by Ivan Herman.

It was also clear that there are many different ways to design a query language. There's even the concern that we don't necessarily need only one standardized means of walking a document tree or looking up items in a table. But it is becoming increasingly important to have a standard query language that works across many different systems.

This document contains Java code fragments that illustrate the use of XQL and the PDOM. They are provided to help you getting a quick start. The authorative source of documentation, of course, are the API docs. Helper functions, e.g. printing XML or creating a DOM from an XML file, is in the new de.gmd.ipsi.domutil package, described in the API docs. A brief introduction how to configure the XQL/PDOM Servlet is also included.

It was also clear that there are many different ways to design a query language. There's even the concern that we don't necessarily need only one standardized means of walking a document tree or looking up items in a table. But it is becoming increasingly important to have a standard query language that works across many different systems.