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Date & Time internationalisation

Discussion in 'Information Technology' started by Nick Stansbury, Oct 28, 2005.

  1. Nick Stansbury

    Nick Stansbury
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    I'm currently building a client/server calendar system with access as
    the primary front end and sql server 2000 at the back end. I also have a
    web-front end that hasn't been finished yet. I've come up against an
    internationalisation issue with time's.

    Users are already using the system from Scandinavia, India and the UK,
    and are soon going to be using it from a number of other countries as well.
    They are putting in events occuring pretty much all over the developed world
    (certainly most major cities).

    My issue concerns time zones - at the moment my policy decision has been
    to put in all events timing's in GMT (UTC for non anglo-philes). This is
    causing a number of problems for my users - most of whom get GMT wrong
    pretty much all the time - they get confused with BST (British summer time)
    and their own daylight savings time - and the whole thing is a mess. What
    I'd like to do is two fold :

    1) Build a "time picker" that works something like this - the user puts in
    08:45 , picks "local time" and then selects a city. My system then converts
    it to GMT and puts it into the appropriate field. The time picker should
    take account of the date the event is taking place at, calculate the
    difference *on that date* between the local time and GMT and make the
    appropriate calculation. (So taking into account daylight savings time it
    would need to adjust by 1 hour for an event taking place in London today,
    but by 0 hours for an event in London next week).

    2) Add a "localisation" feature to our calendar display that allows two
    things - 1) Converts all times *back* into the appropriate local time and
    displays them as such, 2) Converts all times to a fixed time zone - i.e.
    shows all events in New York time. This also would have to check each
    individual date and display them appropriately.

    So...how do I do this? I don't even know where to start! I know there is
    some very obscure TimeZone database here: ftp://elsie.nci.nih.gov/pub/ but
    I've got no clue how to use it - other than parsing a huge number of files
    in different ways. TimeAndDate.Com is building a webservice to do this sort
    of thing on a one-off basis - but I reckon that a webservice would be
    restrictively slow to pull data *out* because it would have to make separate
    checks for each event because of daylight savings. Also - how do I join
    these zones to cities? Is there a global database of cities somewhere that I
    could base it on?

    Any pointers anyone?


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