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

From: Kolozali, Sefki <sefki.kolozali@kcl.ac.uk>
Date: Tue, 4 Oct 2016 13:36:05 +0000
To: "public-sdw-wg@w3.org" <public-sdw-wg@w3.org>
Message-ID: <70BBE432-3A99-4DFA-A090-1F1FDF1D06D3@kcl.ac.uk>
Hi Jeremy, Kerry,

    In my approach (https://www.w3.org/2015/spatial/wiki/Proposals_for_rewriting_SSN#Proposal_3_made_by_Sefki), I have linked both the observation and the output of the calculation that has been used (e.g. average of observations took place in every 5 minutes) to the prov: entity. This made sense to me as we still don’t know what is the activity at observation level: it is still raw data without any meaning attached to it. One we extract the information from sensory observation, I call it prov:activity as we can clearly state what is the activity going on in the sensory environment, such as high temperature; someone is walking, sleeping, etc. Finally, I use a sensor node and the owner of the sensor node as a prov:agent. I will be happy to hear your opinions on these choices.

Kind Regards,

Sefki Kolozali
Research Associate
Environmental Research Group, MRC-PHE Centre for Environment & Health
Analytical & Environmental Sciences
Faculty of Life Sciences & Medicine
King’s College London

E-mail: sefki.kolozali@kcl.ac.uk<mailto:sefki.kolozali@kcl.ac.uk>



On 3 Oct 2016, at 11:59, Kerry Taylor <kerry.taylor@anu.edu.au<mailto:kerry.taylor@anu.edu.au>> wrote:

I know this has become irrelevant, in light of decisions since made – but
>  SSN seems unnecessarily complex in splitting the problem into SensorOutput, Observation and ActivityOfSensing; OM does this in two classes: Result and Observation.
This is not true. SSN  also uses only two classes. Activityof Sensing is not an SSN term. It was merely proposed in [1]  specifically for the purpose of reconciling the differences between O&M and SSN.

[1] Compton, Corsar, Taylor “Sensor Data Provenance: SSNO and PROV-O Together at Last” Oct  2014  http://ceur-ws.org/Vol-1401/tc-ssn2014-complete.pdf#page=69

From: Jeremy Tandy [mailto:jeremy.tandy@gmail.com]
Sent: Wednesday, 24 August 2016 11:49 PM
To: Little, Chris <chris.little@metoffice.gov.uk<mailto:chris.little@metoffice.gov.uk>>; Simon.Cox@csiro.au<mailto:Simon.Cox@csiro.au>; public-sdw-wg@w3.org<mailto:public-sdw-wg@w3.org>
Subject: Re: SSN/SOSA/O&M: is an observation an event, activity, or information object?

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:

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.


From: Simon.Cox@csiro.au<mailto: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 defined the concept:

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 pagehttps://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


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 (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

More info:  https://www.w3.org/2015/spatial/wiki/Meetings:SSN-Telecon20160823


Received on Tuesday, 4 October 2016 13:39:19 UTC

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