HTTP Time Protocol is a time synchronization tool that uses Web server responses (HTTP headers) instead of the NTP protocol. If you are behind a corporate firewall, NAT device, or proxy server, HTP will still be able to synchronize the time. For high precision time synchronization, use ntpd.
libmsntp is a full-featured, compact, portable SNTP library. libmsntp provides SNTP client and server functionality in a shared library with a simple API. SNTP (RFC 2030) is a simplified version of NTP, which allows precise synchronization of system clocks over a best-effort network.