eXist-db is a feature rich Open Source native XML database
eXist-db is a native XML database featuring efficient, index-based XQuery processing, extensions for keyword search, XUpdate support, XSLT support, XForms support, REST and tight integration with existing XML development tools. Moved to Github - https://www.github.com/exist-db/exist
Cross-platform C++ libraries with a network/internet focus.
NOTE: Current source code as well as bugs/patches are on GitHub:
https://github.com/pocoproject/poco/
C++ class libraries for network-centric, portable applications, integrated perfectly with the C++ Standard Library. Includes network protocols (Sockets, HTTP, FTP, SMTP, POP3, etc.), SQL database access and XML parsing. Licensed under Boost license.