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

From: <s.kolozali@surrey.ac.uk>
Date: Tue, 4 Oct 2016 13:19:34 +0000
To: <kerry.taylor@anu.edu.au>
CC: <jeremy.tandy@gmail.com>, <chris.little@metoffice.gov.uk>, <Simon.Cox@csiro.au>, <public-sdw-wg@w3.org>
Message-ID: <94D33A9D-42AB-4523-84C2-6FA365940EF5@surrey.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 Fellow
Institute for Communication Systems (ICS), home of the 5G Innovation Centre (room 07 BA 01)
Faculty of Engineering and Physical Sciences
University of Surrey
Guildford, Surrey, GU2 7XH, United Kingdom
Tel: +44 (0)1483 689490

E-mail: s.kolozali@s<mailto:s.kolozali@qmul.ac.uk>urrey.ac.uk<http://urrey.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 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


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 13:21:23 UTC

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