[georss] multiple locations and time
Knoth, Brian D.
bknoth at mitre.org
Fri Mar 2 09:28:37 EST 2007
Mikel:
After sleeping on this, I'm not entirely comfortable that this is an
appropriate solution for my particular user base. It is a great
suggestion and I can see how it abides by the philosophy of using
what's available and also that it would probably fit very well with the
timeline capability that you've got in the worldkit viewer. However, it
is an odd way for our users to be presented with data that they are
familiar seeing in the way that I've outlined. In fact, in our case RSS
is riding on top of an underlying Web Service mechanism of getting at
the same data, and I'd like to keep them as synchronized as possible in
structure.
So, that kind of brings me back to needing a way of associating
multiple locations with an item and time windows with those locations.
How about this solution - I'm not aware of any restriction in the RSS
2.0/Atom specifications which limit the cardinality of like elements in
the feed, so I think it is valid to have multiple <georss:where>
elements. I'm I correct in this?
If that is ok, then if I have an external schema which defines global
attributes, could I use those attributes in the <georss:where> to
identify time periods and continue to use the existing geoRSS
GML/Simple profiles as they are currently defined?
So, for example:
<rss version="2.0" xmlns:dt="http://mydatetime <http://mydatetime> "
xmlns:georss="http://www.georss.org/georss"
xmlns:gml="http://www.opengis.net/gml">
<channel>
<item>
<title>Flight 2202</title>
<description>non-stop flight from Boston to San
Jose</description>
<link>
http://airlines/flightdetails/2202</link>
<xCal:dtstart>2007-03-07T11:00:00Z</xCal:dtstart>
<xCal:dtend>2007-03-07T17:00:00Z</xCal:dtstart>
<georss:where dt:begin="2007-03-07T11:00:00Z"
dt:end="2007-03-07T11:05:00Z">
<gml:Point>
<gml:description>Takeoff</gml:description>
<gml:pos>42.367157 -71.010054</gml:pos>
</gml:Point>
</georss:where>
<georss:where dt:begin="2007-03-07T16:45:00Z"
dt:end="2007-03-07T17:15:00Z">
<gml:Point>
<gml:description>Takeoff</gml:description>
<gml:pos>37.361400 -121.928031</gml:pos>
</gml:Point>
</georss:where>
</item>
</channel>
</rss>
What do you think?
brian
________________________________
From: Mikel Maron [mailto:mikel_maron at yahoo.com]
Sent: Thursday, March 01, 2007 3:21 PM
To: Knoth, Brian D.; Joshua Lieberman; georss at lists.eogeo.org
Subject: Re: [georss] multiple locations and time
Brian,
Couldn't Takeoff and Landing be represented as two items, which
can be associated together by sharing the same <link>?
<rss ...>
<channel>
<title>Today's Flights</title>
<item>
<title>Flight 2202 Takeoff</title>
<description>non-stop flight from Boston to San
Jose</description>
http://airlines/flightdetails/2202
<xCal:dtstart>2007-03-07T11:00:00Z</xCal:dtstart>
<xCal:dtend>2007-03-07T11:05:00Z</xCal:dtend>
<georss:where>
<gml:Envelope>
<gml:lowerCorner>42.367157
-71.010054</gml:lowerCorner>
<gml:upperCorner>42.367157
-71.010054</gml:upperCorner>
</gml:Envelope>
</georss:where>
<georss:relationshiptag>Takeoff</georss:relationshiptag>
</item>
<item>
<title>Flight 2202 Landing</title>
<description>non-stop flight from Boston to San
Jose</description>
http://airlines/flightdetails/2202
<xCal:dtstart>2007-03-07T16:45:00Z</xCal:dtstart>
<xCal:dtend>2007-03-07T17:15:00Z</xCal:dtendt>
<georss:where>
<gml:Envelope>
<gml:lowerCorner>37.361400
-121.928031</gml:lowerCorner>
<gml:upperCorner>37.361400
-121.928031</gml:upperCorner>
</gml:Envelope>
</georss:where>
<georss:relationshiptag>Landing</georss:relationshiptag>
</item>
</channel>
</rss>
-Mikel
----- Original Message ----
From: "Knoth, Brian D." <bknoth at mitre.org>
To: Mikel Maron <mikel_maron at yahoo.com>; Joshua Lieberman
<josh at oklieb.net>; georss at lists.eogeo.org
Sent: Thursday, March 1, 2007 7:59:34 PM
Subject: RE: [georss] multiple locations and time
Mikel:
I've taken a look at the RSS source behind the temporal mapping
that you sent. As much as I agree with the philosophy of trying to use
what's available as much as possible, I just can't figure out how to
use that approach for the case I'm trying to develop. The example that
you have provided is simple enough that the single position and single
time are both related directly to the item, so they can be easily
correlated. In other words, the time says that the item is valid
between begin and end. The W3C georss then gives the position of that
item. So, ok, while the item is valid, here is where it is.
The problem I am addressing is a bit different. The item has a
lifetime (which can be expressed by xCal extensions), and within that
lifetime the item has a history, a current and a projected collection
of locations with their own time slices. I'm of the position (no pun
intended) that the location time slices must be associated directly
with the location and not loosely linked with the item.
Josh provided to me an excellent example of this using
<gml:history> to capture time with location, but it was defined within
a proprietary namespace and definition, and that's most likely the path
we will have to take. All I'm wondering is couldn't the geoRSS GML
profile be easily extended to also support this concept and provide
foundational data support for temporal mapping applications (such as
what you've done with worldkit)?
I think I've given something like this before, and I know it is
not currently supported, but it's kind of what I am looking for:
<rss ...>
<channel>
<title>Today's Flights</title>
<item>
<title>Flight 2202</title>
<description>non-stop flight from Boston to San
Jose</description>
http://airlines/flightdetails/2202
<xCal:dtstart>2007-03-07T11:00:00Z</xCal:dtstart>
<xCal:dtend>2007-03-07T17:00:00Z</xCal:dtstart>
<georss:where>
<gml:EnvelopeWithTimePeriod>
<gml:description>Takeoff</gml:description>
<gml:lowerCorner>42.367157
-71.010054</gml:lowerCorner>
<gml:upperCorner>42.367157
-71.010054</gml:upperCorner>
<gml:timePosition
indeterminatePosition="before">2007-03-07T11:00:00Z</gml:timePosition>
<gml:timePosition
indeterminatePosition="after">2007-03-07T11:05:00Z</gml:timePosition>
</gml:EnvelopeWithTimePeriod>
</georss:where>
<georss:where>
<gml:EnvelopeWithTimePeriod>
<gml:description>Landing</gml:description>
<gml:lowerCorner>37.361400
-121.928031</gml:lowerCorner>
<gml:upperCorner>37.361400
-121.928031</gml:upperCorner>
<gml:timePosition
indeterminatePosition="before">2007-03-07T16:45:00Z</gml:timePosition>
<gml:timePosition
indeterminatePosition="after">2007-03-07T17:15:00Z</gml:timePosition>
</gml:EnvelopeWithTimePeriod>
</georss:where>
</item>
</channel>
</rss>
I just don't see a clean way of representing this type of
information by decoupling the time periods from the locations and
somehow associating them at the <item> level.
brian
________________________________
From: Mikel Maron [mailto:mikel_maron at yahoo.com]
Sent: Wednesday, February 28, 2007 8:41 AM
To: Knoth, Brian D.; Joshua Lieberman;
georss at lists.eogeo.org
Subject: Re: [georss] WAS: GeoRSS Validation Service?
RETURNING TO: multiple locations and time
Hi Brian
Don't want to belabor the issue, but I very much share
your interest in representing time and space,
and my inkling on the best way to go is leveraging RSS
time/event namespaces already in use.
Small pieces, loosely joined, of simple targeted
vocabularies. I sent some links in the thread a few
weeks back, here's another demo of using the
Upcoming.org GeoRSS/Event feeds
http://worldkit.org/upcoming/
If you 'd like to pursue this course, well, let's do
it!
Mikel
----- Original Message ----
From: "Knoth, Brian D." <bknoth at mitre.org>
To: Joshua Lieberman <josh at oklieb.net>;
georss at lists.eogeo.org
Sent: Wednesday, February 28, 2007 12:28:06 PM
Subject: Re: [georss] WAS: GeoRSS Validation Service?
RETURNING TO: multiple locations and time
Josh,
If by Give-and-Take, you mean that I should go off and
implement my own
extension(s) or utilize some combination of existing
extensions for
time windows and locations (while providing a loose
referential linking
between them) to support what I need, then I feel I
have been very
accommodating this. These are the suggestions that I've
received and
I'm being forced to accept them because my original
recommendation to
this mailing list of simply allowing the GML
representation of space
with time in the geoRSS profile has been discarded.
I just don't understand how an extension whose main
purpose which is to
represent location (ie, geoRSS:where) can ignore the
fact that stuff is
at a place at a specific time, usually for a period of
time, and then
at some other place for other period of time. This fact
just seems so
basic that to ignore it seriously limits the
applicability of geoRSS to
anything more than possibly just the world of blogging.
GE does a great
job of activating and deactivating things that are
outside of their
time windows when TimePeriods are specified in KML.
I've heard some
unsubstantiated rumors that GE may support geoRSS in
the future - if
that is the case, shouldn't the hooks at least be
inserted into geoRSS
now to begin preparing for that usage?
So you are absolutely correct...I can build proprietary
extensions and
mechanisms for supporting this in our RSS feeds. I have
felt, and still
strongly do feel, that the proper place for this is
within a maturing
RSS extension such as geoRSS which, hopefully for its
own adoption
sake, can provide the building blocks necessary to
support
functionality required by not only the Flikrs and
blogs, but also
Enterprise RSS as well.
VR
brian
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