Re: Proposals (was Re: Architecture of SOSA/SSN integration)

Hi
I just replied to a previous thread about a couple of different ways of
doing the SSN part - but I think we all violently agree with the basis of
Phil's proposall, and accept that SSN can add some extra stuff as required,
provided it doesnt redefine anything already covered in SOSA.

One minor point - there is not a clean formal O&M ontology, so I beleive
the work on alignement has already been done by making SOSA definitions
consistent with the O&M text, and that is should be possible to "align"
with the ISO-19150 encoded version of the O&M model - not that this seems
to add value other than providing that consistency of interpretation. So
nothing to do and no nasty dependencies for the lightweight SOSA I think.

Rob

On Thu, 2 Feb 2017 at 08:52 Krzysztof Janowicz <janowicz@ucsb.edu> wrote:

> Okay, I see. Sorry for causing the confusion :-). Great that you agree on
> two namespaces as well!
>
>
> On 02/01/2017 01:47 PM, Joshua Lieberman wrote:
>
> Jano,
>
> There is nothing more to “get”. I’m agreeing to two namespaces because
> people will expect it for two different (if related) concept collections.
>
> Josh
>
> On Feb 1, 2017, at 4:03 PM, Krzysztof Janowicz <janowicz@ucsb.edu> wrote:
>
> I am really sorry Josh but I still don't get it. We would have
> http://www.w3.org/ns/sosa <http://www.w3.org/ns/sosa-ssn> and
> http://www.w3.org/ns/ssn <http://www.w3.org/ns/sosa-ssn>. Both of them
> would resolve to an information resource about each of them in the same way
> we did for the old-SSN. This also provides a very easy handle to understand
> whether somebody uses/implies the more generic SOSA class or a version that
> also adds additional axioms, i.e., the SSN class. A namespace is a very
> nice way to do this and in line with the dereferencing you mentioned as
> well as popular services such as prefix.cc. We are not giving up on
> anything with having two namespaces, we are just increasing usability.
>
> Jano
>
>
>
> On 02/01/2017 12:52 PM, Joshua Lieberman wrote:
>
> The simplest possible meaning here. If a namespace is defined somewhere,
> such as an ontology document, then people expect to be able to use the
> namespace definition also as a URL that resolves to information about
> everything that is defined / identified in that namespace. If we have:
>
> sosa-ssn: http://www.w3.org/ns/sosa-ssn
>
> sosa-ssn:SosaVocabulary
> sosa-ssn:SsnOntology
>
> People will still expect to be able to resolve
> http://www.w3.org/ns/sos-ssn alone and it will need to document or at
> least point to both constructs. To accommodate this idiosyncratic behavior
> and still “isolate” SOSA, we’ll need to have separate SOS and SSN
> namespaces.
>
> —Josh
>
>
> On Feb 1, 2017, at 3:42 PM, Krzysztof Janowicz <janowicz@ucsb.edu> wrote:
>
> Hi Josh,
>
> I’m also reluctantly agreeing that we should use two namespaces because a
> number of people have pointed out that linked data users increasingly
> expect namespaces to be overloaded with meaning and resolvable to
> documentation as URL’s in their own right.
>
>
> Could you explain what you mean here? I am not sure whether I am following
> your argumentation. For something like a namespace resolver, e.g.,
> http://prefix.cc/ , having two namespaces would be great; see also Phil's
> follow-up email.
>
> Best,
> Jano
>
>
>
> On 02/01/2017 12:34 PM, Joshua Lieberman wrote:
>
> Phil,
>
> Thanks for making the proposal. I think that’s where we’ve been
> converging, that terms are defined informally in SOSA to have the same
> scope as in SSN, so that they can be reused in SSN. There are not a lot of
> formal mechanisms to make that distinction clear, however, so we have to
> use narrative and other tools to indicate character of each term set (SOSA:
> core vocabulary and SSN: ontology built from core vocabulary adding
> additional concepts).
>
> I’m also reluctantly agreeing that we should use two namespaces because a
> number of people have pointed out that linked data users increasingly
> expect namespaces to be overloaded with meaning and resolvable to
> documentation as URL’s in their own right.
>
> My preference is for Prop 2A as the term profile is also variously used
> (most assume it means a Type 1 profile that restricts the scope of the
> profiled specification).
>
> The most important alignment for both SOSA and SSN from an OGC point of
> view is with O&M and to SensorML. I hope we can focus on the statements for
> that to pull this together.
>
> —Josh
>
> On Feb 1, 2017, at 3:12 PM, Phil Archer <phila@w3.org> wrote:
>
> Thanks for pointing out that there is more to SSN than what's in the
> mapping table, I should have checked that.
>
> OK, so then I do think the SSN-only terms should be in the ssn namespace,
> but where a term exists in SOSA, that's the one we use. I don't think that
> SSN-only terms should be defined in the SOSA namespace. Therefore, my
> proposals become:
>
> Proposal 1: That where vocabulary terms are defined in the SOSA namespace,
> no new term should be defined for SSN.
>
> Then:
>
> Proposal 2A: That SSN is characterised as a semantic layer on top of SOSA,
> with additional terms.
>
> OR
>
> Proposal 2B: That SSN is characterised as a profile of SOSA.
>
> I hope this slight change does not diminish your support Krzysztof.
>
> Phil
>
>
>
> On 01/02/2017 18:33, Krzysztof Janowicz wrote:
>
> Dear Phil, all,
>
> Thanks a lot for your thoughts and providing this overview. I would like
> to express my *strongest* possible support for your proposal and hope we
> can finally move forward and understand that no single solution will
> make everybody perfectly happy. What you are proposing is largely in
> line with what many of us have been suggesting and working on for
> months. Please find detailed comments in line.
>
> I believe the currently published document expresses the consensus
> view that SOSA is the semantically light weight core and that SSN is
> the semantically richer and more specific ontology.
>
>
> Yes, exactly. But please let me add a few more important detail here.
> SOSA is not only lightweight it also targets a different audience,
> namely those that would typically be attracted to schema.org-style
> semantic annotations. Hence, SSN can/should "use" (e.g., import
> subclass, load, profile, etc. [use whatever term makes you happy here])
> SOSA but not the other way around. Consequently, SOSA has to be designed
> in a way that it can be used entirely independently of SSN. On the other
> hand, SSN really has to use SOSA in some way and here is why: As we
> discussed before, SOSA also acts as a interoperability fallback level.
> What we do *not* want is that SOSA and SSN users cannot exchange data.
> However, and following the current design principles of SOSA, SOSA also
> acts as common core of both, and, thus SSN users and SOSA users can
> indeed exchange data although they do so on a more abstract level. If
> you like object-oriented design/programming, then this idea should sound
> familiar as it is underlying interfaces, generics, inheritance, and so
> forth, and it has been immensely successful.
>
> It defines a class of Actuation that does not appear in SSN or the
> others. Nothing more to say.
>
>
> Yes, and this is not a problem. Same for Sample. We simply forgot about
> this in the old-SSN.
>
>
> Both SOSA and SSN have an Observation class. In my view,
> ssn:Observation should be deleted and SSN users should use
> sosa:Observation. Ditto for all classes where any differences can be
> ironed out.
>
>
> Yes, exactly. This is where many of us hope to go and this is what has
> been proposed over and over again. Btw, Observation is really the only
> critical part here as O&M and old-SSN had a clear difference here. This
> is not dramatic, just something that we need to work on. I have some
> ideas for this that would also solve our current hasValue problem (I
> wrote an email about this some days ago and will report back on results
> asap with the hope to receive feedback).
>
> But again, it's the SOSA namespace that wins. If we need to tweak the
> SOSA definitions, do it.
>
>
> Yes!
>
>
> Then we get to sosa:ObservableProperty and ssn:Property.
>
> Looking at the two definitions, there are differences but they look
> very minor to my eyes with sosa:ObservableProperty looking slightly
> more general, so, again, I'd delete ssn:Property.
>
>
> Yes! And keeping in mind that SOSA is more general by design. This also
> explains why from a set-theoretic perspective SOSA categories (due to
> the lightweight semantics of SOSA classes) are more inclusive than SSN
> categories and, in fact, contain them. Please also note that due to the
> fact that SOSA has a more lightweight semantics, we need more detailed
> human readable class descriptions and this is why we have a bit more
> text and examples then we had in the old-SSN. In the old-SSN we also
> made some mistakes that we can clean up, nobody is perfect after all.
>
>
> Only when we get to sosa:Result do we see something different, i.e.
> ssn:SensorOutput and ssn:ObservationValue. OK, so here, for me, are
> the only classes in the ssn namespace, both of which are subclasses of
> sosa:Result.
>
>
> We need to change how we handle values as this part got lost when we
> removed the direct linkage to DUL. I am working on this based on the new
> version of the QUDT ontology (http://qudt.org/). This will make sure we
> are compatible with a very important and widely used ontology. I will
> report back on my results as soon as we have agreed on your proposal.
> Otherwise I will have to change everything over and over again.
>
> What's the difference between sosa:hosts and sosa:attachedSystem ? Do
> we need both?
>
>
> SOSA should not have an attachedSystem relation. Do you mean SSN?
>
>
> Hang on, that's *it*. There is no more.
>
>
> Agreed. This is why we have always tried to highlight that although we
> have different opinions and different proposals, they differ by rather
> small pieces. Almost all of us agree that we can adjust/align/integrate
> SOSA and SSN without major efforts.
>
>
> Question: do we really need ssn:SensorOutput and ssn:ObservationValue
> or could we live with just sosa:Result?
>
>
> See above. This problem will go away on its own.
>
> Based on the mapping table, I end up with just *two* classes and *no*
> properties in the SSN namespace.
>
>
> There is more to SSN, namely survival ranges of sensors and so forth.
>
> So we're talking here about SSN essentially adding further semantic
> constraints on SOSA, not new terms (except possibly two new classes).
>
>
> SSN contains more, see above. Deployment is another example. This is not
> a problem as these classes and relations do not appear in SOSA. SOSA is
> simply not the place where one would go into all the details on how a
> sensor is constructed and so on, but SSN allows us to do so.
>
> The SOSA vocabulary (it doesn't have rich enough semantics to be
> called an ontology in my view) is deliberately defined with loose
> semantics - just enough for everyday applications.
>
>
> I am fine with calling it a vocabulary but as it has OWL axioms I would
> prefer to call it ontology. Again, I am fine with whatever the majority
> wants. Maybe 'vocabulary' is even better for our envisioned end users.
>
> We've been arguing about the namespace for the SSN terms. Kerry has
> been saying that we don't need another namespace. Reading through the
> mapping table, now I see why: personally, I only see one vocabulary.
>
>
> This is where I would personally disagree as SSN adds substantially more
> content (see above) and end users tend to confuse namespaces and use
> them for communication. Also note that SSN is a bit of an odd name as we
> ended up not really talking a lot about (N)etworks. That said, and while
> I would strongly prefer two namespaces for clarity, if we all agree to
> go with your suggestion, I will certainly not risk a discussion on
> namespaces if everybody else would prefer just one namespace.
>
> 6. Alignment to OGC Observations and Measurements
>
> Looks like a pretty straightforward alignment to me. I presume
> consideration was given to using O&M terms directly in SOSA? Can they
> not be used directly? If not, it looks to me as if SOSA terms could be
> declared as sub classes and properties of O&M terms.
>
>
> Yes and we have Simon Cox on the team so this should really not be a
> difficult issue. I hope we can give Simon a more active role here but
> this is a separate discussion. O&M is really important if we want
> SOSA/new-SSN to be a success story.
>
> What about om-lite and sam-lite?
>
>
> IMHO, om-lite is a subset of O&M and is already compatible with SOSA. In
> fact, Simon posted an alignment between SOSA and om-lite in summer of
> 2016 on our github.
>
>
> 8. Alignment to DOLCE+DNS Ultralite upper ontology (DUL)
>
> For me this is optional but if there's no harm in including it, go ahead.
>
>
> This is a problematic point especially with respect to old-SSN and
> new-SSN. I can demonstrate why this is problematic in a separate email
> but I would strongly suggest we have the DUL alignment as an optional
> part. Which should not be confused with me saying that it does not
> matter. Also note that the idea of contextualized/scoped/optional axioms
> does not exist in W3C OWL.
>
>
> Proposal 1: That all vocabulary terms are defined in the SOSA namespace.
>
> Proposal 2A: That SSN is characterised as a semantic layer on top of
> SOSA.
>
> OR
>
> Proposal 2B: That SSN is characterised as a profile of SOSA.
>
> Personally, I'd vote in favour of 1 and 2B.
>
>
> I would vote for 1 but this is probably a more difficult discussion.
>
> Dear SSN members, please let us accept Phil's proposal without getting
> into little infights, very particular details, changes, endless change
> request, and so forth as we did over the past 6+ months. No proposal
> will ever make everybody absolutely happy but Phil's proposal comes from
> a neutral stance and captures almost all aspects we discussed so many
> times and that many of us supported by their votes over and over and
> over again. More details remain to be clarified, but let us do this
> after we agreed on this general outline.
>
> Jano
>
>
> On 02/01/2017 08:40 AM, Phil Archer wrote:
>
> Dear all,
>
> I am sorry that I was only able to take part in the first half of the
> meeting yesterday.
>
> I've been looking at the mapping table [1] and trying to make some
> more sense of what I see and offer how I personally would choose to
> proceed. In doing this I admit that I have been too lax, allowing the
> task force to continue its work without taking the time to understand
> the detail of what was being discussed. This is unhelpful and I bear
> some responsibility at least for the current malaise. I offer what
> follows as a possible way forward. In doing so, please be sure that I
> do not have any special powers. This is not a diktat from W3C, just a
> proposal from a WG member.
>
> I believe the currently published document expresses the consensus
> view that SOSA is the semantically light weight core and that SSN is
> the semantically richer and more specific ontology.
>
> OK, so we start with SOSA.
>
> It defines a class of Actuation that does not appear in SSN or the
> others. Nothing more to say.
>
> Both SOSA and SSN have an Observation class. In my view,
> ssn:Observation should be deleted and SSN users should use
> sosa:Observation. Ditto for all classes where any differences can be
> ironed out.
>
> But again, it's the SOSA namespace that wins. If we need to tweak the
> SOSA definitions, do it.
>
> Then we get to sosa:ObservableProperty and ssn:Property.
>
> Looking at the two definitions, there are differences but they look
> very minor to my eyes with sosa:ObservableProperty looking slightly
> more general, so, again, I'd delete ssn:Property.
>
> Only when we get to sosa:Result do we see something different, i.e.
> ssn:SensorOutput and ssn:ObservationValue. OK, so here, for me, are
> the only classes in the ssn namespace, both of which are subclasses of
> sosa:Result.
>
> On to properties.
>
> Using the same logic, I would delete:
>
> ssn:featureOfInterest
> ssn:observationResult
> ssn:observes
> ssn:observedProperty
> ssn:sensingMethodUsed
> ssn:madeObservation (and move ssn:observedBy to the sosa namespace to
> be consistent with the other inverse properties)
> ssn:onPlatform
> ssn:observationSamplingTime
> ssn:observationResultTime
>
> What's the difference between sosa:hosts and sosa:attachedSystem ? Do
> we need both?
>
> Hang on, that's *it*. There is no more.
>
> Based on the mapping table, I end up with just *two* classes and *no*
> properties in the SSN namespace.
>
> Question: do we really need ssn:SensorOutput and ssn:ObservationValue
> or could we live with just sosa:Result?
>
> So we're talking here about SSN essentially adding further semantic
> constraints on SOSA, not new terms (except possibly two new classes).
>
> That's what I call a profile, i.e. a way in which a particular
> vocabulary is used, complete with cardinality constraints and more
> finely tuned semantics. We can add textual usage notes and
> descriptions as well as semantic axioms but I see no new terms to add.
>
> So here's my table of contents for the document:
>
> 1. Introduction
> 2. Developments since the initial 2009 publication of SSN
> 3. Modularization
> 4. The SOSA ontology
> 5. The SSN Semantic Layer
> The SOSA vocabulary (it doesn't have rich enough semantics to be
> called an ontology in my view) is deliberately defined with loose
> semantics - just enough for everyday applications.
>
> Where more precise semantics are needed, such as in @@@use case@@@ and
> @@@ use case@@@ an additional layer can be applied. This allows data
> encoded using SOSA to be processed using an OWL resoner.
>
> Then define all the semantics you like in a file at /ns/ssn/.
>
> We've been arguing about the namespace for the SSN terms. Kerry has
> been saying that we don't need another namespace. Reading through the
> mapping table, now I see why: personally, I only see one vocabulary.
>
> 6. Alignment to OGC Observations and Measurements
>
> Looks like a pretty straightforward alignment to me. I presume
> consideration was given to using O&M terms directly in SOSA? Can they
> not be used directly? If not, it looks to me as if SOSA terms could be
> declared as sub classes and properties of O&M terms.
>
> I'd say that this can be part of the normative definition of SOSA.
>
> What about om-lite and sam-lite?
>
> Well, they look pretty similar too. Am I right that these are
> CSIRO-only ontologies? In which case, I'd say that any alignment is up
> to CSIRO to do and publish.
>
> 7. Alignment to SSN of the SSN-XG, ssn-ssnx.
>
> I'd include those assertions in a sub chapter of the one on SSN.
>
> 8. Alignment to DOLCE+DNS Ultralite upper ontology (DUL)
>
> For me this is optional but if there's no harm in including it, go ahead.
>
> I am feeling very guilty. I should have looked at that mapping table
> before now. I think I have learned a lesson.
>
> Proposal 1: That all vocabulary terms are defined in the SOSA namespace.
>
> Proposal 2A: That SSN is characterised as a semantic layer on top of
> SOSA.
>
> OR
>
> Proposal 2B: That SSN is characterised as a profile of SOSA.
>
> Personally, I'd vote in favour of 1 and 2B.
>
> Phil
>
>
> [1] https://www.w3.org/2015/spatial/wiki/Mapping_Table
>
> On 31/01/2017 23:39, Armin Haller wrote:
>
> Hi,
>
> Herewith I am trying to summarise what has been discussed in today’s
> meeting, what was discussed and proposed on the list and what we have
> already decided on earlier in the working group:
>
>
> ·         SOSA and SSN use Slash URIs/IRIs
>
> ·         SOSA and SSN use different IRIs and are serialised in
> separate ontology files (everyone expect Kerry agreed on that one,
> although there is her proposal on the wiki stating the same:
>
> https://www.w3.org/2015/spatial/wiki/Proposals_for_rewriting_SSN#Compromise_Proposal_6_made_by_Kerry_January_2017
> )
>
>
> ·         SOSA and SSN may use different ontology namespaces
>
> ·         SOSA uses simple semantics as decided upon earlier (i.e.
> owl classes, datatype and object properties, inverse properties, but
> no domain/range and no other owl restrictions)
>
> ·         SSN imports SOS
>
>