Draugiem-api is a project mainly written in Java, it's free.
draugiem.lv API implementation for Java
draugiem.lv API implementation for JAVA. Supports usage in standard webapps and also Google App Engine. See META-INF/draugiem.propeties for configuration options
When using with Google App Engine make sure all draugiem-api project dependencies are included and sessions are enabled in appengine-web.xml
NOTE: this project is not yet fully tested!