BaseX is a light-weight, high-performance, and scalable XML database system and XPath/XQuery processor, including full support for the W3C Update and Full Text extensions. An interactive and user-friendly GUI frontend gives you great insight into large XML data instances. It is platform independent and works out of the box.
With MetaModel, you use a type-safe SQL-like API for querying any datastore. It is a data access framework providing a common interface for exploration and querying of different types of datastores. It isn't a data mapping framework. Instead, it emphasizes abstraction of metadata and the ability to add data sources at runtime, making MetaModel great for generic data processing applications, but less so for applications modeled around a particular domain.
Redland is a set of C libraries providing a high-level API for the Resource Description Framework (RDF), allowing it to be stored, parsed, serialized, queried, and manipulated. It has an object-based, modular design and comes with detailed reference documentation and examples. Redland supports all RDF vocabularies such as FOAF, RSS 1.0, Dublin Core, DOAP, and OWL, the query languages SPARQL and RDQL, and all RDF syntaxes including Turtle, RDF/XML, RDF/JSON, RSS, Atom, RDFa, and GRDDL.
nexB OpenAssets is a tool for inventorying, managing, and monitoring applications, software, hardware, networks, and generally any IT asset. It is designed so that system administrators, IT, and finance can determine what they have, how it is configured, what it is used for, and how much it is being used, so that informed decisions can be made. It complements existing network management software, integrates with a growing number of protocols and tools, and features no-agent discovery and inventory, configuration management including dependencies and correlation, monitoring, and reporting. It makes extensive and innovative use of XML, Xpath, and Xquery.
X-Hive/DB is a powerful native XML database designed for software developers who require advanced XML data processing and storage functionality within their applications. The comprehensive X-Hive/DB Java API contains methods for storing, querying, retrieving, transforming, and publishing XML data. X-Hive/DB supports all major W3C standards, such as XQuery, XPath, DOM, XPointer, XML Schemas, and more.
OpenDaemon provides a model of work along with its supporting APIs that allow anybody to implement a server of any kind, for any protocol. Its main goal is to help provide an advanced data storage solution that is flexible enough to allow its user to choose from a broad set of parsers, data extractors, processors, or any other supporting API. The generic server platform system is meant to make development of the data storage solution more open and distributable.
QOF (Query Object Framework), provides a set of C Language utilities for performing generic structured complex queries on a set of data held by a set of C/C++ objects. This framework is unique in that it does not require SQL or any database at all to perform the query. Thus, it allows programmers to add query support to their applications without having to hook into an SQL database.
PhiloLogic is a full-text database engine developed for humanities computing text analysis by the ARTFL Project and the Digital Library Development Center at the University of Chicago. It is optimized for fast searching across very large collections of documents. It currently supports TEI-Lite, TEI XML, and TEI SGML documents.
XMLDB uses an RDBMS to persist arbitrary XML documents. Due to its storage mechanism, searching for and recalling documents is extremely quick. You can also perform XSL translation on documents with surprising speed. The library can be used in any program to store libxml2 documents. A PHP module is also included, making XMLDB into a complete three-tier Web application development suite.