W3C home > Mailing lists > Public > www-rdf-calendar@w3.org > May 2001

RE: RDF calendar schemas

From: Shannon J. Clark <shannon@jigzaw.com>
Date: Wed, 30 May 2001 16:38:34 -0500
To: <www-rdf-calendar@w3.org>
Well, for all that iCalendar is complex, there is also a reason for this
complexity - time based information is NOT simple or trivial, very quickly a
number of individually seeming "simple" requirements combine to form a very
complicated problem domain.

For a few "simple" illustrations consider the following questions - think
about how a "simple" solution might address all of them.

One - what is the problem that the RDF is intended to be employed to solve?
Calendars mean many DIFFERENT things to people - a doctor's use of a
calendar is different from a students which is different from a room
scheduler's which differs from an airlines.

Two - what is the usage pattern of the RDF based software? Is it designed
for ONE user? For MANY users? For Multiple organizations running on multiple
servers coordinating scheduling questions?

Three - Do you have to consider timezones?

Four - Do you have to handle Daylight Savings?

Five - will you have to handle multiple languages? Unicode and/or multi-byte
languages? Calendar systems OTHER than Gregorian? (i.e. Lunar calendars

Six - are you working ONLY in the future? Or does your calendar have to
handle the past as well - if so how far in the future or how far back in the
past? The needs of an astronomer or geologist are very different from those
of businessman.

Seven - Are the "users" even humans? People have proposed using elements of
iCalendar in phone switches and internet cache systems that have complex
time-dependant rules to execute and schedule - the issues and requirements
here can be VERY different from those of human end users.

There are many more - reoccurring events, how to handle and consider events,
what assumptions if any to make about "units" (for example do you ignore
Leap Seconds?)

Hope this helps spark conversation and thought.


Shannon J. Clark
CEO - JigZaw, Inc
1.800.4.JIGZAW (454.4929)

-----Original Message-----
From: www-rdf-calendar-request@w3.org
[mailto:www-rdf-calendar-request@w3.org]On Behalf Of Aaron Swartz
Sent: Wednesday, May 30, 2001 4:21 PM
To: Libby Miller; www-rdf-calendar@w3.org
Subject: Re: RDF calendar schemas

Libby Miller <Libby.Miller@bristol.ac.uk> wrote:

> I would suggest that we set ourselves the task of producing potential
> RDF schemas based on iCalendar and a deadline of the end of July to do
> so. It may be that one schema fits our needs; we'll see what happens.

I'm not sure that building on iCalendar is the correct thing to do. As
others have mentioned, iCalendar is rather complex. Personally I'd like to
build a very simple schema which can be easily extended to include more
information. I was noodling around today and came up with:

    [ a :Activity ] :where ... ; :when .... ; :who ... .

I haven't looked at iCal carefully so I don't know if this is compatible.
However, I would suggest that whatever we suggest can be easily subsetted to
something of this simplicity.

[ Aaron Swartz | me@aaronsw.com | http://www.aaronsw.com ]
Received on Wednesday, 30 May 2001 17:38:53 UTC

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