ABCL provides a callback interface to java objects, next to these calls:

 - ext:make-socket
 - ext:socket-close
 - ext:make-server-socket
 - ext:socket-accept
 - ext:get-socket-stream (returning an io-stream)

abcl-swank (see SLIME) shows how to call directly into java.


See for the sockets implementation:

 - src/org/armedbear/lisp
   * socket.lisp
   * socket_stream.java
   * SocketStream.java