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RE: State of SSN: arguments in favour of a single name and namespace, proposal, the SEAS example, proposal of action

From: <Simon.Cox@csiro.au>
Date: Mon, 6 Feb 2017 03:19:17 +0000
To: <maxime.lefrancois@emse.fr>, <janowicz@ucsb.edu>, <phila@w3.org>, <kerry.taylor@anu.edu.au>, <armin.haller@anu.edu.au>, <public-sdw-wg@w3.org>
Message-ID: <25424afbf4024452b4674f243524ac35@exch1-mel.nexus.csiro.au>
Thanks Maxime.

Ø  SOSA appears to me as arbitrarily incomplete, uncoherent, and therefore unuseful.

Yes, it is incomplete. Whether that makes in unuseful depends on the use you have in mind. A high priority we had when proposing SOSA was the ‘schema.org’ community. We understand they don’t care much about logical completeness and even less about formal axiomatization. In some early versions of SOSA I played around with adding some of the pieces you have identified as ‘missing’ but pulled back when that looked like blowing out the count of classes and properties.

What you see there now is a compromise, partly based on hunches about what classes and properties would be most often used by the schema.org community, but complemented with ‘just enough’ properties for the design to have logical heart.  The basis for the compromise is not fully clear, and your list here is a very helpful inventory of some of what’s missing.

Ø  To name but a few that are listed at [2]:

… and I would add

-          ‘SamplingActivity’ (compare with ‘Actuation’ and ‘Observation’) and

-          ‘SamplingDevice’ (compare with ‘Actuator’ and ‘Sensor’),
but could also see those in a separate module – arguably, description of the sampling process is a minority sport, though I believe the significance of Samples themselves is enough that it must be in the core.

The content question I think we need to resolve (else do a little engineering to fix …) is whether there is anything in SOSA which prevents it from serving as a core to SSN/SOSA-Full.


From: Maxime Lefrançois [mailto:maxime.lefrancois@emse.fr]
Sent: Sunday, 5 February, 2017 21:59
To: janowicz@ucsb.edu; Phil Archer <phila@w3.org>; Kerry Taylor <kerry.taylor@anu.edu.au>; Armin Haller <armin.haller@anu.edu.au>; SDW WG Public List <public-sdw-wg@w3.org>; Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au>
Subject: Re: State of SSN: arguments in favour of a single name and namespace, proposal, the SEAS example, proposal of action

Dear Jano,

+1. And there are other reasons as well, namely the branding for instance.  We anticipate a large user base for SOSA (substantially larger than (full) SSN). We want SOSA to be a recognizable product and end users will assume that they can refer to it by its own namespace, look up the namespace at prefix.cc., and so on (see also Josh's argument).

The argument that could convince me is the one from Simon [1].  I'll add: given SSN will import SOSA, then it *will also* talk about actuators and sampling. Furthermore, because SSN adds axioms to e.g., sensors, and for completeness reasons, I would vote for SSN to include axioms for actuators and sampling. Hence I agree that SSN as a name might become too restrictive for an ontology where actuators and sampling became so much important.

So to make it clear, I am still in favor of a single name and namespace. I could live with any mention of SSN being renamed "SOSA Full", and:
 - the new ssn namespace being dropped
 - the old ssn namespace redirect to an ontology document that imports SSN full and defines alignment with sosa terms.

Lets follow the KISS principle and do what the vast majority of end users would expect. The more we add, the more we have to explain, the more has to be maintained, the more can be misunderstood, and so on. Finally, we would also all need to fully understand the other proposal, discuss it, compare it with current practice, anticipate whether this will be the mainstream approach in the future (as we hope SOSA/SSN will be around for many years to come), and so on.

As a user of what will come out of this working group, I must warn you that in its current state, SOSA appears to me as arbitrarily incomplete, uncoherent, and therefore unuseful. To name but a few that are listed at [2]:
 1. there is no relation between feature of interest and observable property
 2. links exist between observation/sensor and feature of interest/observable property, but there exists no parallel link with actuation/actuator and feature of interest/observable property
 3. why is phenomenonTime a object property whereas resultTime is a datatype property ? This is counter confusing because they both end with "time".
 4. there is the Result for observation/actuation, but there is nothing to describe the Command of the actuation.
 5. there is no link between the actuator/sensor and the procedure it implements
 6. result time could be replace with prov:generatedAtTime
 7. there is invokedBy/invokes for actuators, but there is only madeObservation for sensors
 8. domain of isFeatureOfInterestOf includes only feature of interest, but range of inverse property hasFeatureOfInterest includes both feature of interest and sample.
 9. actuation and observation are in some "virtual box" one could give a proper name to, such as "Procedure execution"
 10. actuator and sensor are in some "virtual box" one could give a proper name to, such as "Procedure executor"
 11. to me one should keep sosa:hasResult but delete sosa:Result, sosa:resultTime and sosa:hasValue.

The core modules of the SEAS ontologies are already some kind of generalization of SSN and look very similar to SOSA without the aforementioned uncoherences. I could also try to push my own solution as "the new standard", but I won't. I believe in team work, discussion and consensus.

If we accept to solve these problems, then I already agreed to update the SEAS ontologies so that they are built on top of SOSA. This would indirectly make the SEAS implementations become implementations for SOSA [3]. Otherwise, I won't be part of the user base.

Other proposals for mimicking SSN for actuators exist in the wild, see [4]. I believe we want to attract the users base of this ontology too.

Let's not experiment. We already agreed on two URLs and two files, let's go with two clear namespaces as well and move to the pressing problems we need to sort out before we run out of time. These discussions really distract us. There is *no* damage in using two namespaces but there is clear damage from having an incomplete product by the end of the month.

I'm not experimenting here. I really hope the work I do can help the group move forward by:

 - having proper turtle documents that, when you look at them, can trigger the idea that SOSA and SSN were written by the same group;
 - specifying properly how the w3c server should serve the different documents;
 - identifying issues in SOSA and help solving them.
 - being able to do agile modifications to implement right away any suggestion so that we discuss on products that are ready to be delivered (Agile).

[1] - https://lists.w3.org/Archives/Public/public-sdw-wg/2016Nov/0051.html

[2] - https://github.com/maximelefrancois86/sdw/tree/one-namespace/ssn/one-namespace

[3] - http://seas.asema.com/

[4] - http://www.irit.fr/recherches/MELODI/ontologies/SAN#<http://www.irit.fr/recherches/MELODI/ontologies/SAN>

Received on Monday, 6 February 2017 03:20:03 UTC

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