Jackrabbit - Content Repository in Java

Apache Jackrabbit is a Content Repository fully conforming to JCR specification. Jackrabbit content repository is a hierarchical content store with support for structured and unstructured content, full text search, versioning, transactions, observation, and more.

It provides access to its repository via Web Interface, Command line , WebDAV and RMI. The content could be stored in file system or in database. It supports REST API so that it could be accessed from any programming language.