Unix domain socket

support ordered and reliable transmission of datagrams (unix)
all communication occurs entirely within the operating system kernel.
Unix domain sockets use the file system as their address name space.

unix:// provides access to a socket stream connection in the Unix domain.
udg:// provides an alternate transport to a Unix domain socket using the user datagram protocol. (unordered and unreliable)

Usage:

    unix:///tmp/mysock
    udg:///tmp/mysock