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Re: SSN/SOSA/O&M: is an observation an event, activity, or information object?

From: Krzysztof Janowicz <janowicz@ucsb.edu>
Date: Tue, 6 Sep 2016 13:36:32 -0700
To: public-sdw-wg@w3.org
Message-ID: <3634603f-7d85-2c0a-2abc-4d163327ee9b@ucsb.edu>
Note that SOSA-core explicitly does not introduce terms such as events 
and activities and that we discussed before that we should try to avoid 
them.  First, these terms carry a lot of ontological commitments that 
almost nobody but ontology engineers really understand nor need. Even 
those who understand these terms discuss their meaning back and forth 
since 20 years. For instance, an 'object' can be understood as simply 
being a very slowly changing event. For instance, it may come as a 
surprise to some of you that if we model an observation as an event, 
then an observation cannot have a location. While I agree with this, 
many web-developers would find this cumbersome to deal with. Most 
importantly, how many queries will be written where one searches for an 
'event' instead of an observation or actuation?

Best,
Krzysztof



On 08/24/2016 06:48 AM, Jeremy Tandy wrote:
> Simon- thank you for clearly stating the challenge.
>
> Binding things back to PROV-O seems sensible; especially as it helps 
> clarify the disjoint definitions of Observation in OM and SSN. 
> Referring to the "must read" resource [1] that Simon identified ...
>
> """
> PROV-O provides just three base classes: Entity, Activity and Agent. 
> om:Observation is sub-classed from prov:Activity, while 
> ssn:Observation is sub-classed from prov:Entity.
> """
>
> For me, it seems natural to treat Observation as an Activity ... it's 
> something that's done at a particular time using a specified process. 
> It produces a some data (the result) ... the data, an information 
> resource, is an Entity. SSN seems unnecessarily complex in splitting 
> the problem into SensorOutput, Observation and ActivityOfSensing; OM 
> does this in two classes: Result and Observation.
>
> At first glance the hierarchy Simon proposed in SOSA [2] seems 
> sensible - with top-level Classes of Procedure, Device and Activity. 
> I'm lacking the time to do a thorough road test of the complete 
> hierarchy though. However, I note that in OM the fact that OM_Process 
> could describe anything from a list of repeatable instructions (a 
> recipe or sorts) through to an instance of a sensor with a specific 
> calibration has always been somewhat confusing. It's good to see these 
> concerns teased out into Procedure and Device, recognising that a 
> Procedure will often _use_ a Device.
>
> HTH, Jeremy
>
> [1]:https://goo.gl/TKlX1l
> [2]: 
> https://www.w3.org/2015/spatial/wiki/index.php?title=SOSA_Ontology&oldid=2342#Procedures_vs_Devices 
>
>
> On Wed, 24 Aug 2016 at 11:07 Little, Chris 
> <chris.little@metoffice.gov.uk <mailto:chris.little@metoffice.gov.uk>> 
> wrote:
>
>     Simon,
>
>     Very helpful. Thank you.
>
>     As an ontology ignoramus, I think “The result of an observation is
>     an estimate of the value of a property of some feature” says it
>     all. Whether there is one ontology (“to rule them all” as someone
>     said) or two or three covering your different aspects consistently
>     I leave to others to thrash out.
>
>     Chris
>
>     *From:*Simon.Cox@csiro.au [mailto:Simon.Cox@csiro.au
>     <mailto:Simon.Cox@csiro.au>]
>     *Sent:* Tuesday, August 23, 2016 11:42 PM
>     *To:* public-sdw-wg@w3.org <mailto:public-sdw-wg@w3.org>
>     *Subject:* SSN/SOSA/O&M: is an observation an event, activity, or
>     information object?
>
>     Kerry had asked me to discuss this in the SSN meeting today. We
>     ran out of time, so here is a summary and some reading material.
>
>     There are a lot of links below, so if you only have time to look
>     at one, probably make it this: https://goo.gl/TKlX1l (and “Read
>     the full publication”, which is just a set of slides).
>
>     The problem
>
>     ----------------
>
>     The key concern is
>
>     ·SSN had the class “Observation” as a sub-class of
>     dul:SocialObject. This is explicitly disjoint with dul:Event. So
>     ssn:Observation appears to be a _/record/_ of an sensing activity,
>     however
>
>     ·O&M http://portal.opengeospatial.org/files/41579
>     <http://portal.opengeospatial.org/files/41579> defined the concept:
>
>     4.11
>
>     observation
>
>     act of measuring or otherwise determining the value of a property
>
>     and includes a class “Observation” which is introduced as follows:
>
>     7.1.2 Observation
>
>     An observation is an act associated with a discrete time instant
>     or period through which a number, term or other
>
>     symbol is assigned to a phenomenon [2]. It involves application of
>     a specified procedure, such as a sensor,
>
>     instrument, algorithm or process chain. The procedure may be
>     applied in-situ, remotely, or ex-situ with respect
>
>     to the sampling location. The result of an observation is an
>     estimate of the value of a property of some feature.
>
>     So the word “Observation” appears to be used for two different
>     things in SSN and O&M – a record, or an activity or event,
>     respectively.
>
>     Background resources
>
>     ---------------------------
>
>     See a presentation I made at last year’s AGU meeting “Pitfalls in
>     alignment of observation models resolved using PROV as an upper
>     ontology” - The presentation is on ResearchGate
>     https://www.researchgate.net/publication/305809446_Pitfalls_in_alignment_of_observation_models_resolved_using_PROV_as_an_upper_ontology
>
>
>     I also discussed the issue in my Semantic Web Journal paper
>     “Ontology for observations and sampling features, with alignments
>     to existing models”
>
>     http://www.semantic-web-journal.net/system/files/swj1237.pdf - see
>     particularly the discussion in section 5.
>
>     In turn, these leaned on a paper by Mick Compton, David Corsar and
>     Kerry “Sensor Data Provenance: SSNO and PROV-O Together at Last”
>     http://ceur-ws.org/Vol-1401/paper-05.pdf
>
>     Implementation in SOSA
>
>     ------------------------------
>
>     The initial SOSA-core took a related approach, with high-level
>     classes for Procedure, Device, and Activity, which I introduced in
>     an attempt to make the terminology around actuation, sensing and
>     sampling consistent
>
>     – see this version of the SOSA wiki page
>     https://www.w3.org/2015/spatial/wiki/index.php?title=SOSA_Ontology&oldid=2342
>
>
>     Subsequently this hierarchy has been removed from SOSA, partly
>     because it was felt that SOSA-core was getting too big.
>
>     But I wonder if this has merely kicked the can down the road. For
>     me sorting the procedures, devices and activities for
>     observing/sensing, actuating, sampling into these groupings
>     clarifies things, but perhaps that just means I’m a stamp-collector.
>
>     Issue tracker
>
>     ---------------
>
>     This topic is in the tracker as
>
>     -ISSUE-67: what is an ssn:observation
>     https://www.w3.org/2015/spatial/track/issues/67
>
>     And these are closely related issues:
>
>     -ISSUE-62: Align SSN with O&M
>     https://www.w3.org/2015/spatial/track/issues/62
>
>     -ISSUE-53: Align ssn with prov-o
>     https://www.w3.org/2015/spatial/track/issues/53
>
>     Simon
>
>     *From:*Kerry Taylor [mailto:kerry.taylor@anu.edu.au]
>     *Sent:* Monday, 22 August 2016 11:03 PM
>     *To:* public-sdw-wg@w3.org <mailto:public-sdw-wg@w3.org>
>     *Subject:* sdw: ssn meeting this week
>
>     Dear SDW,
>
>     For the SSN meeting this week *23 August 2016 21:00 UTC
>     <http://www.timeanddate.com/worldclock/fixedtime.html?iso=20160823T21&ah=1&msg=SSN%20Call>*,
>     the agenda as follows is proposed.
>
>     Phil, Simon and Frans, please be prepared to lead respective
>     topics with your name on it.  Frans – I can look after  action-111
>     if you are not present.
>
>     **
>
>      1. SSN: Issue tracking and public discussion (PhilA?)
>      2. UCR -- action-111 see
>         https://lists.w3.org/Archives/Public/public-sdw-wg/2016Aug/0084.html
>         (Frans?)
>      3. UCR - reviewing for SSN requirements issue-73 and
>         https://www.w3.org/2016/08/17-sdw-minutes#item05
>         <https://www.w3.org/2016/08/17-sdw-minutes#item05> (Kerry)
>      4. SSN/SOSA/O&M: is an observation an event, activity, or
>         information object? (Simon?)
>      5. Web of Things: joint meeting with oneM2M today
>         https://lists.w3.org/Archives/Public/public-sdw-wg/2016Aug/0070.html
>
>      6. Web of Things: meet at Lisbon, possibly
>         https://www.w3.org/wiki/TPAC2016/SessionIdeas
>         <https://www.w3.org/wiki/TPAC2016/SessionIdeas>
>
>     More info:
>     https://www.w3.org/2015/spatial/wiki/Meetings:SSN-Telecon20160823
>
>     Kerry
>


-- 
Krzysztof Janowicz

Geography Department, University of California, Santa Barbara
4830 Ellison Hall, Santa Barbara, CA 93106-4060

Email: jano@geog.ucsb.edu
Webpage: http://geog.ucsb.edu/~jano/
Semantic Web Journal: http://www.semantic-web-journal.net
Received on Tuesday, 6 September 2016 20:37:09 UTC

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