On looking at RFCs For a useful exercise in putting network theory into practice, we can write an RFC-868 ‘client’

How does a ‘protocols’ arise? Since the inception of networking, it’s been a practice of the Internet Engineering Task Force (IETF) to circulate draft-documents known as RFCs (“Request For Comment”) which set forth detailed proposals for new network protocol standards, and then after a period for discussion and revisions to adopt these as official IETF ‘standards’

RFC868 – Time Protocol One of the early (and brief) examples of an RFC is this two-page description of a client-and-server application that provides an accurate time-and-date to computers anywhere on the Internet It was adopted a quarter-century ago, but is still in use -- although newer protocols now offer several superior capabilities

UTC The ‘Time Protocol’ expresses the current time, at a specific location on the Earth’s surface, in terms of the number of seconds that have elapsed since January 1 st, 1900 This measurement is called Coordinated Universal Time, formerly known as GMT (Greenwich Mean Time), but allows both the time and the date to be calculated for locations in any ‘time-zone’ on the Earth

In-class exercise #1 Read RFC868 and write a ‘client’ sockets program which obtains the UTC integer from an official U.S. Naval Observatory server, then computes and displays the current time-of-day here in California now (i.e., Pacific Daylight Time), given that it’s seven hours later in Greenwich, England Server’s hostname: ‘time-nw.nist.gov’

In-class exercise #2 Enhance your solution by also displaying the current date in California now (PDT) This enhancement is more challenging, as you’ll need to use information about which years are ‘leap’ years – and the rules are slightly more complicated than those you may have learned in grammar school! (See Robert Wolf’s on our website)