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.
Emdros is a corpus query system for storing and searching linguistically annotated text. It is very generic, supporting almost any kind of annotation from almost any linguistic theory. All linguistic levels of analysis are supported, including phonology, morphology, the lexical level, syntax, and discourse. The core libraries act as a middleware layer between a client and an underlying SQL database. MySQL, PostgreSQL, and SQLite are supported.
The SODA Native XML Database System is a native XML database that provides efficient management of large amounts of XML data. It is based on a multi-user, client-server architecture with a generic query processing layer that can easily support different query languages. In this lightweight version, user- defined indexes and query optimizations have been removed, however full transaction support (commits and rollbacks) and crash recovery are available.