Re: (Lost in the noise perhaps - so asking again) - Is a trailing slash 'better' than a trailing hash for vocabs namespace IRIs?

Dear Pat,

I just wanted to make sure we were on the same page regarding the "best 
of both worlds" situation, but clearly we are.

To answer your question about my points c) and d) below:
when the client retrieves something from http://ex.co/x/, it contains 
some triples about http://ex.co/x/Z. But when the client wants to know 
exactly what http://ex.co/x/Z is, how does it determine that it does 
/not need /to retrieve http://ex.co/x/Z, because it already retrieved 
everything there is to know about http://ex.co/x/Z when it retrieved 
http://ex.co/x/ ?

One way to achieve this would be to include, in the content of 
http://ex.co/x/, the triple
<http://ex.co/x/Z> rdfs:isDefinedBy <http://ex.co/x/>.

but again, that is a convention that both the server and the client have 
to share.


Overall, I think we agree that slash-IRIs provide more flexibility. However,

- that flexibility requires more work on the server side (to maintain 
consistency between the "focused" representations and the "large" 
representation), and
- it only pays off if the client is smart enough to understand the hints 
provided by the server (otherwise, the dumb client may only retrieve the 
"focused" representations -- or worse, retrieve all the "focused" 
representations AND the "large" representation).

 > But all I'm looking for here is this community's opinion on whether 
we can offer a clear, *single*, *preference* for the creators of new RDF 
vocabularies going forward

Again, I believe this is a matter of trade-of, so my personal opinion 
is: no, there is no clear single solution that is better than the other 
in all cases.

 > Newbies don't want to have to 'decide for themselves' if they can 
help it when learning new technology - and so they'll just continue the 
current practice of cutting-and-pasting what they see as most prevalent 
out there today [i.e. hash-IRIs]

... and I personally believe this is an OK approach for newbies. 
Whenever your ontology becomes too big for this approach (as Schema.org 
or QUDT), and/or you look for more flexibility, you need more expertise 
-- and then you need to make informed choices. :)

   pa

On 10/10/2022 11:08, Pat McBennett wrote:
> Hi Pierre-Antoine,
>
> Thanks so much for engaging in the discussion - I really, really 
> appreciate it! (I'm re-sending this as I just noticed that the tabbing 
> from my GMail response didn't come through formatted correctly - so 
> I've prefixed quotes with initials of [PAC] for [Pierre-Antonie Champin])
>
> You bring up some great points, but in my view, and with a bit more 
> clarification from my side, I think they all seem to actually be 
> reinforcing the argument for slashes (just as a *preference* when 
> creating new vocabs)!
>
>     [PAC] "In the general case, when you encounter an IRI of the form
>     http://ex.co/x/Y, you can not assume that http://ex.co/x/ will
>     contain the definition of http://ex.co/x/Y together with other
>     related terms."
>
> Yep, absolutely, I totally agree - this is the wild-wild-west of the 
> World Wide Web after all, so yeah, regardless of slashes or hashes, we 
> can never assume anything at all when dereferencing any IRI anywhere.
> And so yeah, nobody should ever make the assumption you point out here 
> (it never even occurred to me that anyone would!). As you say below, 
> that's why `rdfs:isDefinedBy` is so useful (and should be a general 
> Best Practice for vocabs anyway, I'd say).
>
>     [PAC] "For this you need,
>
>     a) the server to provide an affordance in the description of
>     http://ex.co/x/Y pointing to http://ex.co/x/  (e.g. by using
>     rdfs:isDefinedBy)
>
> Yep - totally agree. Which is why I always highly recommend (as a 
> separate, but related, general Best Practice) that all vocab terms 
> should always provide an `rdfs:isDefinedBy` triple regardless. 
> (Thankfully that term's local name (i.e., 'isDefinedBy') is very 
> intuitively self-explanatory!)
>
>     b) the client to understand and follow that affordance."
>
> Well, yeah, kinda, but only *if* that client *wants* to be able to 
> take advantage of that extremely handy and helpful little affordance 
> to follow-its-nose. And given the client needs to understand RDF (to 
> some minimal degree at least) in the first place to be working with 
> RDF vocabs at all, that doesn't seem like a problem to me, or any kind 
> of an issue at all.
>
> In other words, all I'm stating is that if we *prefered* slashes, then 
> any client wishing to understand what any individual IRI *is* can 
> simply deference that IRI (i.e., isn't that just the first principle 
> of Linked Data really!). And they should always (in my opinion) be 
> able to expect to get back *only* a representation of whatever that 
> IRI represents. So *if* the IRI they dereferenced happened to be an 
> individual vocab term, then (only with slash-based vocabs) they'd 
> correctly get back data on just that one vocab term.
>
> (I'd consider it merely a Best Practice that they might *also* be able 
> to expect a `rdfs:isDefinedBy` link to the overall vocab within which 
> that single vocab term is defined - but they only need to understand 
> and/or follow that link if they ever wanted to *also* discover 
> information on the containing is-defined-by vocab.)
> So in other words, I only see goodness here, and a simple consistent 
> expression of Linked Data first principles (i.e., all 'things of 
> interest' should have uniquely *dereferencable* IRIs, and you can 
> choose to follow-your-nose to 'more info' if you want to, and you 
> understand the predicates leading the way).
>
>     [PAC] "c) the description at http://ex.co/x/ to include some
>     information about any term (e.g. http://ex.co/x/Z) in contains
>     stating "there is nothing more to know about this term" (e.g. by
>     using rdfs:isDefinedBy again)"
>
> I don't quite follow this point - perhaps you could elaborate a 
> little, or provide some sample Turtle...? (For example, I would expect 
> the description at http://ex.co/x/ (assuming that to be a vocab 
> namespace IRI) to indeed contain *all* of the information about the 
> vocab itself (like it's versioning info, preferred prefix, creation 
> date, etc.), and *all* the information about *all* of the terms that 
> that vocab contains/defines - i.e., exactly as QUDT do today when you 
> click on their namespace IRI: https://qudt.org/schema/qudt/ (although 
> they only seem to provide Turtle, and not a content-negotiable full 
> HTML representation that I'd prefer to see them provide from my 
> browser (e.g., DPV does provide a lovely 'complete vocab' that is a 
> content-negotiable (i.e., HTML or Turtle) representation when you 
> dereference it's namespace IRI today: http://www.w3.org/ns/dpv#)).
>
>
>     [PAC] "d) the client to understand that statement and refrain from
>     fetching http://ex.co/x/Z later on"
>
> I didn't follow the above point, so this one loses me too, but (I 
> think) this comes down to clients needing to know (regardless of slash 
> or hash) the basic difference between an `owl:Ontology` and an 
> `rdf:Class` or `rdfs:Property` (i.e., between 'a full vocab' and 'a 
> term in a vocab') in the responses they get from servers when they are 
> dereferencing vocab-related IRIs anyway. I don't think the issues 
> around caching are majorly affected by the slash/hash choice - but 
> perhaps I'm missing your real point here...
>
>
>     [PAC] "So you don't get "the best of both world" as automatically
>     as you suggest."
>
> Oh yeah, absolutely - so we agree again. I should have been clearer 
> perhaps - I certainly didn't mean to imply that getting 
> the-best-of-both-worlds was in any way 'automatic' at all. As I said 
> later in my post, getting both will require more work on the server 
> side, or from tooling.
> All I'm trying to emphasize is that slashes provide *a means* to get 
> the-best-of-both-worlds, whereas with hashes the best servers can ever 
> offer to clients (regardless of the needs or wants of those clients) 
> is to return information on all terms in the entire vocab (since, by 
> HTTP design, the server will never receive the hash fragment in any 
> HTTP request), and so you can never, ever offer any client *the 
> option* to just retrieve a single vocab term's information and nothing 
> else *if that's what the client wants/needs/prefers*.
>
>     [PAC] "Terms of a vocabulary/ontology rarely make sense in
>     isolation. So arguably, serving the entire vocabulary provides you
>     with enough context to understand/use the term appropriately."
>
> Well, I wouldn't agree with that at all. I think 
> QUDT's CurrencyUnit (https://qudt.org/schema/qudt/CurrencyUnit) is a 
> great example of where it makes perfect sense (i.e., all I want to 
> know is what QUDT *mean* by a 'CurrencyUnit'). And surely no-one would 
> argue that Schema.org should switch from its current slash to use hash 
> instead, because terms like Person (https://schema.org/Person) need 
> context from the entire 2,500 terms defined in Schema.org as a whole.
>
> But I do certainly agree with your point that individual terms should 
> indeed provide enough context to understand/use the term - but I think 
> all that context should be provided *in isolation* within the vocab's 
> definition of that term itself, and should certainly not require 
> downloading the entire vocabulary - i.e., examples of precisely that 
> are `rdfs:isDefinedBy`, `rdfs:domain`, `schema:rangeIncludes`, 
> `rdfs:seeAlso`, `skos:related`, `skos:narrower`, etc.
> Now, given that much of that 'term-specific context' would actually be 
> IRIs, it should then be up to the client to decide if it now wishes to 
> dereference each of those individual links with multiple HTTP 
> requests, or if it actually wishes to now download the entire 
> vocabulary in one HTTP request (again, only slashes offer all clients 
> the choice and flexibility for them to decide between those options 
> for themselves).
>
>     [PAC] "And then you get "bombarded with a huge document"..."
>
> Yep, but again my point is that only with slash do clients get at 
> least the option, or the ability, or the possibility, to *choose for 
> themselves* whether they get bombarded with the entire vocab in one 
> HTTP request or not.
>
>
>         [PAC] "[PMcB] - So doesn't that demonstrate my whole point -
>         i..e, that with slashes I can get the best of both worlds
>
>     I don't think so. They are different trade-offs between providing
>     targeted content vs. reducing the number of HTTP queries, and
>     between working with dumb clients and/or dumb servers vs.
>     requiring more coordination between them  (e.g. providing and
>     following rdfs:isDefinedBy links)."
>
> Well to emphasize my point, with slashes I *can* get 
> the-best-of-both-worlds, with hashes I *can't*.
> Yep, for sure there are tradeoffs, and indeed implementing the full 
> set of options (with full conneg, and providing/generating individual 
> term-specific static HTML pages, etc.) definitely requires more 
> server-side work/tooling. But I'd argue that adopting slash still 
> doesn't *require* that any of that work be done at all, for example, 
> if all you have to work with are dumb servers - i.e. your dumb server 
> can just continue as always, serving up the full vocab information for 
> all requests using the exact same single static page it uses today 
> with hash, by simply using a single URL rewrite rule to rewrite 
> http://ex.co/x/Z to http://ex.co/x#Z <http://ex.co/x/Z>. Sure, that 
> breaks the client expectation somewhat (i.e., "I only asked for info 
> on term Z, and you gave me info on all the vocab terms - but at least 
> you provided the HTML anchor so that my browser jumped down 
> automatically to the info for term Z!") - but that's a worst-case 
> scenario (i.e., a scenario that may have been forced on you due to 
> only having dumb servers and no server-side tooling), and yet it's 
> still no worse than what you get today with hashes (i.e., it *is* what 
> you get today with hashes).
>
>         [PAC] "[PMcB} - And that's why I posit that slashes are simply
>         'more correct' (i.e., since *only* slashes can ever allow
>         servers to always know exactly, unambiguously, what a
>         requesting client is really looking for
>
>     I don't by that. The server can never know exactly nor
>     unambiguously what the intent of the client is, nor should it
>     (separation of concerns)."
>
> Sure, of course :) ! So let me re-phrase my point - only slashes 
> provide the means for the server to *see* the *full/complete IRI* that 
> a client may wish to de-reference. In other words, with hashes, by 
> HTTP design, the client *must* strip off the hash fragment (if any) 
> before putting the HTTP request on the wire - hence the server can't 
> ever distinguish between a client asking for info on a single term 
> (e.g., GET http://ex.co/x#Z <http://ex.co/x/Z>) or a client wishing 
> for info on the entire vocab (e.g., GET http://ex.co/x# 
> <http://ex.co/x/Z> or just GET http://ex.co/x <http://ex.co/x/Z>).
>
>
>     [PAC] "Cant' help but cite the priority of consituencies
>     remininded in
>     https://www.w3.org/TR/design-principles/#priority-of-constituencies"
>
> Yep, exactly (we agree again!) - but for me, this is precisely an 
> argument for slashes - i.e., hashes restrict what clients can possibly 
> get back from a server (i.e., they'll always get the full vocab 
> information back), whereas slashes at least provide *the potential* 
> for servers to offer clients more flexibility and choice (i.e., info 
> just on individual terms, *or* info on the full vocab).
> So surely giving clients *more* choice (with slashes), not less (with 
> hashes), is putting their needs first (since we can't possibly ever 
> know up-front, for any vocab, the 'needs' of all potential users 
> (i.e., the entire user base of the Web) for vocabs we publish, right!?
>
>     [PAC] "Also, in a distributed setting such as the web, you can not
>     assume that all other parties will always do the right thing™."
>
> Again, I totally agree (who wouldn't!).
> But all I'm looking for here is this community's opinion on whether we 
> can offer a clear, *single*, *preference* for the creators of new RDF 
> vocabularies going forward. I think we can, and that *preference* 
> should be using slashes (i.e., not a requirement, or a mandate, or 
> something anyone can ever force people to do). I just think the 
> current state of guidance in the Linked Data community is too loose 
> and therefore off-putting for newbies - i.e., "You can do either, 
> there are pro's and con's, but it doesn't really matter much, so you 
> can just decide for yourself". Newbies don't want to have to 'decide 
> for themselves' if they can help it when learning new technology - and 
> so they'll just continue the current practice of cutting-and-pasting 
> what they see as most prevalent out there today (e.g., nearly all the 
> W3C vocab examples today), which will most likely mean repeating the 
> 'mistake' of using hashes, and thereby 'hurting' the longer-term 
> options for client/user software that may wish to have the ability (at 
> some future stage perhaps) to be able to choose for themselves between 
> term-specific or full-vocab lookups.
>
> Thanks again Pierre-Antoine for pushing me to think this through even 
> more thoroughly - I hope it's been somewhat useful for you (and 
> others?) to ponder on too :)
>
> Pat.
>
> *Pat McBennett*, Technical Architect
>
> Contact  | patm@inrupt.com
>
> Connect | WebID <http://pmcb55.inrupt.net/profile/card#me>, GitHub 
> <https://github.com/pmcb55>
>
> Explore  | www.inrupt.com <http://www.inrupt.com/>
>
>
>
>
> On Sat, Oct 8, 2022 at 2:10 AM Pat McBennett <patm@inrupt.com> wrote:
>
>     Hi Pierre-Antoine,
>
>     Thanks so much for engaging in the discussion - I really, really
>     appreciate it!
>
>     You bring up some great points, but in my view, and with a bit
>     more clarification from my side, I think they all seem to actually
>     be reinforcing the argument for slashes (just as a *preference*
>     when creating new vocabs)!
>
>         In the general case, when you encounter an IRI of the form
>         http://ex.co/x/Y, you can not assume that http://ex.co/x/ will
>         contain the definition of http://ex.co/x/Y together with other
>         related terms.
>
>     Yep, absolutely, I totally agree - this is the wild-wild-west of
>     the World Wide Web after all, so yeah, regardless of slashes or
>     hashes, we can never assume anything at all when dereferencing any
>     IRI anywhere.
>     And so yeah, nobody should ever make the assumption you point out
>     here (it never even occurred to me that anyone would!). As you say
>     below, that's why `rdfs:isDefinedBy` is so useful (and should be a
>     general Best Practice for vocabs anyway, I'd say).
>
>         For this you need,
>
>         a) the server to provide an affordance in the description of
>         http://ex.co/x/Y pointing to http://ex.co/x/  (e.g. by using
>         rdfs:isDefinedBy)
>
>     Yep - totally agree. Which is why I always highly recommend (as a
>     separate, but related, general Best Practice) that all vocab terms
>     should always provide an `rdfs:isDefinedBy` triple regardless.
>     (Thankfully that term's local name (i.e., 'isDefinedBy') is very
>     intuitively self-explanatory!)
>
>         b) the client to understand and follow that affordance.
>
>     Well, yeah, kinda, but only *if* that client *wants* to be able to
>     take advantage of that extremely handy and helpful little
>     affordance to follow-its-nose. And given the client needs to
>     understand RDF (to some minimal degree at least) in the first
>     place to be working with RDF vocabs at all, that doesn't seem like
>     a problem to me, or any kind of an issue at all.
>
>     In other words, all I'm stating is that if we *prefered* slashes,
>     then any client wishing to understand what any individual IRI *is*
>     can simply deference that IRI (i.e., isn't that just the first
>     principle of Linked Data really!). And they should always (in my
>     opinion) be able to expect to get back *only* a representation of
>     whatever that IRI represents. So *if* the IRI they dereferenced
>     happened to be an individual vocab term, then (only with
>     slash-based vocabs) they'd correctly get back data on just that
>     one vocab term.
>
>     (I'd consider it merely a Best Practice that they might *also* be
>     able to expect a `rdfs:isDefinedBy` link to the overall vocab
>     within which that single vocab term is defined - but they only
>     need to understand and/or follow that link if they ever wanted to
>     *also* discover information on the containing is-defined-by vocab.)
>     So in other words, I only see goodness here, and a simple
>     consistent expression of Linked Data first principles (i.e., all
>     'things of interest' should have uniquely *dereferencable* IRIs,
>     and you can choose to follow-your-nose to 'more info' if you want
>     to, and you understand the predicates leading the way).
>
>         c) the description at http://ex.co/x/ to include some
>         information about any term (e.g. http://ex.co/x/Z) in contains
>         stating "there is nothing more to know about this term" (e.g.
>         by using rdfs:isDefinedBy again)
>
>     I don't quite follow this point - perhaps you could elaborate a
>     little, or provide some sample Turtle...? (For example, I would
>     expect the description at http://ex.co/x/ (assuming that to be a
>     vocab namespace IRI) to indeed contain *all* of the information
>     about the vocab itself (like it's versioning info, preferred
>     prefix, creation date, etc.), and *all* the information about
>     *all* of the terms that that vocab contains/defines - i.e.,
>     exactly as QUDT do today when you click on their namespace IRI:
>     https://qudt.org/schema/qudt/ (although they only seem to provide
>     Turtle, and not a content-negotiable full HTML representation that
>     I'd prefer to see them provide from my browser (e.g., DPV does
>     provide a lovely 'complete vocab' that is a content-negotiable
>     (i.e., HTML or Turtle) representation when you dereference it's
>     namespace IRI today: http://www.w3.org/ns/dpv#)).
>
>
>         d) the client to understand that statement and refrain from
>         fetching http://ex.co/x/Z later on
>
>     I didn't follow the above point, so this one loses me too, but (I
>     think) this comes down to clients needing to know (regardless of
>     slash or hash) the basic difference between an `owl:Ontology` and
>     an `rdf:Class` or `rdfs:Property` (i.e., between 'a full vocab'
>     and 'a term in a vocab') in the responses they get from servers
>     when they are dereferencing vocab-related IRIs anyway. I don't
>     think the issues around caching are majorly affected by the
>     slash/hash choice - but perhaps I'm missing your real point here...
>
>
>         So you don't get "the best of both world" as automatically as
>         you suggest.
>
>     Oh yeah, absolutely - so we agree again. I should have been
>     clearer perhaps - I certainly didn't mean to imply that getting
>     the-best-of-both-worlds was in any way 'automatic' at all. As I
>     said later in my post, getting both will require more work on the
>     server side, or from tooling.
>     All I'm trying to emphasize is that slashes provide *a means* to
>     get the-best-of-both-worlds, whereas with hashes the best servers
>     can ever offer to clients (regardless of the needs or wants of
>     those clients) is to return information on all terms in the entire
>     vocab (since, by HTTP design, the server will never receive the
>     hash fragment in any HTTP request), and so you can never, ever
>     offer any client *the option* to just retrieve a single vocab
>     term's information and nothing else *if that's what the client
>     wants/needs/prefers*.
>
>         Terms of a vocabulary/ontology rarely make sense in isolation.
>         So arguably, serving the entire vocabulary provides you with
>         enough context to understand/use the term appropriately.
>
>     Well, I wouldn't agree with that at all. I think
>     QUDT's CurrencyUnit (https://qudt.org/schema/qudt/CurrencyUnit) is
>     a great example of where it makes perfect sense (i.e., all I want
>     to know is what QUDT *mean* by a 'CurrencyUnit'). And surely
>     no-one would argue that Schema.org should switch from its current
>     slash to use hash instead, because terms like Person
>     (https://schema.org/Person) need context from the entire 2,500
>     terms defined in Schema.org as a whole.
>
>     But I do certainly agree with your point that individual terms
>     should indeed provide enough context to understand/use the term -
>     but I think all that context should be provided *in isolation*
>     within the vocab's definition of that term itself, and should
>     certainly not require downloading the entire vocabulary - i.e.,
>     examples of precisely that are `rdfs:isDefinedBy`, `rdfs:domain`,
>     `schema:rangeIncludes`, `rdfs:seeAlso`, `skos:related`,
>     `skos:narrower`, etc.
>     Now, given that much of that 'term-specific context' would
>     actually be IRIs, it should then be up to the client to decide if
>     it now wishes to dereference each of those individual links with
>     multiple HTTP requests, or if it actually wishes to now download
>     the entire vocabulary in one HTTP request (again, only slashes
>     offer all clients the choice and flexibility for them to decide
>     between those options for themselves).
>
>         And then you get "bombarded with a huge document"...
>
>     Yep, but again my point is that only with slash do clients get at
>     least the option, or the ability, or the possibility, to *choose
>     for themselves* whether they get bombarded with the entire vocab
>     in one HTTP request or not.
>
>
>             So doesn't that demonstrate my whole point - i..e, that
>             with slashes I can get the best of both worlds
>
>         I don't think so. They are different trade-offs between
>         providing targeted content vs. reducing the number of HTTP
>         queries, and between working with dumb clients and/or dumb
>         servers vs. requiring more coordination between them  (e.g.
>         providing and following rdfs:isDefinedBy links).
>
>     Well to emphasize my point, with slashes I *can* get
>     the-best-of-both-worlds, with hashes I *can't*.
>     Yep, for sure there are tradeoffs, and indeed implementing the
>     full set of options (with full conneg, and providing/generating
>     individual term-specific static HTML pages, etc.) definitely
>     requires more server-side work/tooling. But I'd argue that
>     adopting slash still doesn't *require* that any of that work be
>     done at all, for example, if all you have to work with are dumb
>     servers - i.e. your dumb server can just continue as always,
>     serving up the full vocab information for all requests using the
>     exact same single static page it uses today with hash, by simply
>     using a single URL rewrite rule to rewrite http://ex.co/x/Z to
>     http://ex.co/x#Z <http://ex.co/x/Z>. Sure, that breaks the client
>     expectation somewhat (i.e., "I only asked for info on term Z, and
>     you gave me info on all the vocab terms - but at least you
>     provided the HTML anchor so that my browser jumped down
>     automatically to the info for term Z!") - but that's a worst-case
>     scenario (i.e., a scenario that may have been forced on you due to
>     only having dumb servers and no server-side tooling), and yet it's
>     still no worse than what you get today with hashes (i.e., it *is*
>     what you get today with hashes).
>
>             And that's why I posit that slashes are simply 'more
>             correct' (i.e., since *only* slashes can ever allow
>             servers to always know exactly, unambiguously, what a
>             requesting client is really looking for
>
>         I don't by that. The server can never know exactly nor
>         unambiguously what the intent of the client is, nor should it
>         (separation of concerns).
>
>     Sure, of course :) ! So let me re-phrase my point - only slashes
>     provide the means for the server to *see* the *full/complete IRI*
>     that a client may wish to de-reference. In other words, with
>     hashes, by HTTP design, the client *must* strip off the hash
>     fragment (if any) before putting the HTTP request on the wire -
>     hence the server can't ever distinguish between a client asking
>     for info on a single term (e.g., GET http://ex.co/x#Z

>     <http://ex.co/x/Z>) or a client wishing for info on the entire
>     vocab (e.g., GET http://ex.co/x# <http://ex.co/x/Z> or just GET
>     http://ex.co/x <http://ex.co/x/Z>).
>
>
>         Cant' help but cite the priority of consituencies remininded
>         in
>         https://www.w3.org/TR/design-principles/#priority-of-constituencies

>
>     Yep, exactly (we agree again!) - but for me, this is precisely an
>     argument for slashes - i.e., hashes restrict what clients can
>     possibly get back from a server (i.e., they'll always get the full
>     vocab information back), whereas slashes at least provide *the
>     potential* for servers to offer clients more flexibility and
>     choice (i.e., info just on individual terms, *or* info on the full
>     vocab).
>     So surely giving clients *more* choice (with slashes), not less
>     (with hashes), is putting their needs first (since we can't
>     possibly ever know up-front, for any vocab, the 'needs' of all
>     potential users (i.e., the entire user base of the Web) for vocabs
>     we publish, right!?
>
>         Also, in a distributed setting such as the web, you can not
>         assume that all other parties will always do the right thing™.
>
>     Again, I totally agree (who wouldn't!).
>     But all I'm looking for here is this community's opinion on
>     whether we can offer a clear, *single*, *preference* for the
>     creators of new RDF vocabularies going forward. I think we can,
>     and that *preference* should be using slashes (i.e., not a
>     requirement, or a mandate, or something anyone can ever force
>     people to do). I just think the current state of guidance in the
>     Linked Data community is too loose and therefore off-putting for
>     newbies - i.e., "You can do either, there are pro's and con's, but
>     it doesn't really matter much, so you can just decide for
>     yourself". Newbies don't want to have to 'decide for themselves'
>     if they can help it when learning new technology - and so they'll
>     just continue the current practice of cutting-and-pasting what
>     they see as most prevalent out there today (e.g., nearly all the
>     W3C vocab examples today), which will most likely mean repeating
>     the 'mistake' of using hashes, and thereby 'hurting' the
>     longer-term options for client/user software that may wish to have
>     the ability (at some future stage perhaps) to be able to choose
>     for themselves between term-specific or full-vocab lookups.
>
>     Thanks again Pierre-Antoine for pushing me to think this through
>     even more thoroughly - I hope it's been somewhat useful for you
>     (and others?) to ponder on too :)
>
>     Pat.
>
>
>     *Pat McBennett*, Technical Architect
>
>     Contact  | patm@inrupt.com
>
>     Connect | WebID <http://pmcb55.inrupt.net/profile/card#me>, GitHub
>     <https://github.com/pmcb55>
>
>     Explore  | www.inrupt.com <http://www.inrupt.com/>
>
>
>
>
>
>     On Fri, Oct 7, 2022 at 8:07 AM Pierre-Antoine Champin
>     <pierre-antoine@w3.org> wrote:
>
>         On 07/10/2022 01:49, Pat McBennett wrote:
>
>>         Hi Martynas,
>>
>>         Thanks for the feedback!
>>
>>         But I think any vocabulary can just as easily support that
>>         same caching benefit with slash-based vocab namespace IRIs
>>         too, *without* having to require an initial HTTP request for
>>         *each* term - i.e., by simply returning the entire vocab on
>>         namespace IRI lookups.
>         In the general case, when you encounter an IRI of the form
>         http://ex.co/x/Y, you can not assume that http://ex.co/x/ will
>         contain the definition of http://ex.co/x/Y together with other
>         related terms. For this you need,
>
>         a) the server to provide an affordance in the description of
>         http://ex.co/x/Y pointing to http://ex.co/x/

>         b) the client to understand and follow that affordance (e.g.
>         by using rdfs:isDefinedBy)
>         c) the description at http://ex.co/x/ to include some
>         information about any term (e.g. http://ex.co/x/Z) in contains
>         stating "there is nothing more to know about this term" (e.g.
>         by using rdfs:isDefinedBy again)
>         d) the client to understand that statement and refrain from
>         fetching http://ex.co/x/Z later on
>
>         So you don't get "the best of both world" as automatically as
>         you suggest.
>
>>
>>         I think QUDT is a really nice, simple example that very
>>         easily demonstrates exactly this today. It has a slash
>>         namespace IRI, and if I only ever request info on individual
>>         single vocab terms (e.g., try clicking now on
>>         `https://qudt.org/schema/qudt/CurrencyUnit`) then yes, I'd
>>         encounter that 'HTTP request per lookup' you suggest (but I'd
>>         be getting precisely what I asked for each time!).
>         Terms of a vocabulary/ontology rarely make sense in isolation.
>         So arguably, serving the entire vocabulary provides you with
>         enough context to understand/use the term appropriately.
>>
>>         But I can just as easily avoid that scenario today too by
>>         simply requesting the vocab's namespace IRI instead - e.g.,
>>         try it right now by just clicking on
>>         `https://qudt.org/schema/qudt`

>>         <https://qudt.org/schema/qudt>. See - you get back the entire
>>         vocab containing all the vocab terms in a single HTTP
>>         response, which can be cached and keyed on that one namespace
>>         IRI (exactly as you would if they'd used a hash instead).
>         And then you get "bombarded with a huge document", to quote
>         one of your arguments against hash-IRIs. Seems to me that you
>         get the worst of both worlds here: I had to perform two HTTP
>         queries (one on CurrencyUnit, got get the link to the whole
>         vocab, and one on the vocab) instead of one (with hash IRIs),
>         and I still end up with a huge ontology. (yes, playing devil's
>         advocate here a little)
>>         (I'm not familiar with Jena's OntDocumentManager, but I'm
>>         sure its caching code could easily be extended to take
>>         advantage of servers that choose to server up slash-based
>>         vocabularies as QUDT demonstrates is so feasible today.)
>>         So doesn't that demonstrate my whole point - i..e, that with
>>         slashes I can get the best of both worlds
>
>         I don't think so. They are different trade-offs between
>         providing targeted content vs. reducing the number of HTTP
>         queries, and between working with dumb clients and/or dumb
>         servers vs. requiring more coordination between them  (e.g.
>         providing and following rdfs:isDefinedBy links).
>
>>         (i.e., precise term-specific HTTP responses if I want them,
>>         *and* the entire vocab in a single HTTP response if I want
>>         that too)? Using a hash completely locks me out, forever, of
>>         being able to achieve those lovely clean term-specific responses.
>>         And that's why I posit that slashes are simply 'more correct'
>>         (i.e., since *only* slashes can ever allow servers to always
>>         know exactly, unambiguously, what a requesting client is
>>         really looking for
>         I don't by that. The server can never know exactly nor
>         unambiguously what the intent of the client is, nor should it
>         (separation of concerns
>         <https://en.wikipedia.org/wiki/Separation_of_concerns>).
>>         (i.e., a term-specific response, or an entire vocab
>>         response)), and it does so without losing any of the benefits
>>         of using a hash. (I do, by the way, totally appreciate that
>>         servers choosing to work as the QUDT servers do today might
>>         require a bit more server-side work. But my whole point is to
>>         ask this community which option they consider "more
>>         technically correct today and forever", and not "which option
>>         is easier for servers or vocab
>>         creators/hosters/editors/publishers today in the absence of
>>         any tooling support".
>
>         Cant' help but cite the priority of consituencies remininded
>         in
>         https://www.w3.org/TR/design-principles/#priority-of-constituencies
>
>         "User needs come before the needs of web page authors, which
>         come before the needs of user agent implementors, which come
>         before the needs of specification writers, which come before
>         theoretical purity."
>
>         Don't get me wrong, I get the point of thinking beyond the
>         limitation of current tools. That's a valuable exercise. But
>         practicality does also matter.
>
>         Also, in a distributed setting such as the web, you can not
>         assume that all other parties will always do the right thing™.
>
>           my 2€
>
>           pa
>
>>         In other words, I think that QUDT-server-like behaviour can
>>         be provided easily by tooling, which I'd personally be very
>>         happy to work on contributing :) !).
>>         Cheers,
>>         Pat.
>>
>>         *Pat McBennett*, Technical Architect
>>
>>         Contact  | patm@inrupt.com
>>
>>         Connect | WebID <http://pmcb55.inrupt.net/profile/card#me>,
>>         GitHub <https://github.com/pmcb55>
>>
>>         Explore  | www.inrupt.com <http://www.inrupt.com/>
>>
>>
>>
>>
>>         On Thu, Oct 6, 2022 at 3:44 PM Martynas Jusevičius
>>         <martynas@atomgraph.com> wrote:
>>
>>             Hi Pat,
>>
>>             For one thing, hash URIs are easier to cache because
>>             there is only one document URL. After the initial HTTP
>>             request the whole document can be cached with its URL as
>>             the key. All following term lookups (whose URIs start
>>             with that URL) will hit the cached document.
>>             Slash URIs will require an initial HTTP request for
>>             *each* term and will result in a cache entry per term.
>>
>>             This is based on my experience with Jena's
>>             OntDocumentManager.
>>
>>             Martynas
>>             atomgraph.com <http://atomgraph.com>
>>
>>
>>             On Thu, Oct 6, 2022 at 4:15 PM Pat McBennett
>>             <patm@inrupt.com> wrote:
>>
>>                 So (I think!) I know all the pro's and con's of using
>>                 either a trailing slash or a trailing hash for
>>                 vocab namespace IRIs. Basically it boils down to
>>                 hashes meaning you'll always get info on all the
>>                 terms in a vocabulary, even if you only want info for
>>                 one specific term, whereas using a slash means I can
>>                 always get just the info for any specific, individual
>>                 term I request.
>>
>>                 Note: using slashes provides the ability to get the
>>                 best of both worlds - i.e., small responses when
>>                 explicitly asking for info on just one term, but if
>>                 you want info for all the terms in one HTTP response,
>>                 then just serve up that complete vocab response when
>>                 the base namespace IRI itself is dereferenced.
>>
>>                 Here's a nice simple illustration of the basic
>>                 difference:
>>                 - Slash: QUDT's 'CurrencyUnit' term (i.e., click on
>>                 'https://qudt.org/schema/qudt/CurrencyUnit') and you
>>                 get a nice clean, concise, and precise set of info on
>>                 just the one term you asked for - lovely!
>>
>>                 - Hash: DPV's 'JointDataControllers' (i.e., click on
>>                 'https://w3id.org/dpv#JointDataControllers') and you
>>                 get bombarded with a huge document, with a daunting
>>                 Table of Contents on the left, and info on hundreds
>>                 of other terms that I didn't ask for, and so had no
>>                 interest in whatsoever (don't get me wrong - this is
>>                 fantastically detailed and potentially very useful
>>                 information, but it's simply not what I asked for!).
>>
>>                 So based on the greater flexibility and
>>                 future-proofing of using slash (i.e., it offers the
>>                 best of both worlds, whereas hash is forever
>>                 limited), I've become firmly of the opinion that
>>                 slashes are just 'better' that hashes, and in fact
>>                 are simply 'more correct' (i.e., all IRIs should be
>>                 uniquely dereferencable).
>>
>>                 I also think the distinction is critically important
>>                 when creating vocabularies intended for widespread
>>                 and long-lasting use (such as the DPV vocab above).
>>                 For throw-away or pet projects, sure, it doesn't
>>                 really matter (yet even then, I still think slashes
>>                 are the 'more correct' option).
>>
>>                 I know that the convention from the W3C has tended to
>>                 be to use hashes, but I think in hindsight that was a
>>                 mistake, and that the advice from the Semantic Web
>>                 community as a whole should now be to adopt slashes
>>                 consistently for all new vocabularies. (And it's not
>>                 like using slash has no precedent - major
>>                 'authoritative' vocabs like QUDT, Schema.org, gist,
>>                 SOSA, SSN, (even the venerable FOAF!) all use slash).
>>
>>                 I'd love to hear this group's thoughts. (For
>>                 reference, I did ask the gist community if they
>>                 recorded their discussions around their decision (in
>>                 2019) to formally switch gist from hash to slash
>>                 (here
>>                 <https://github.com/semanticarts/gist/issues/725>),
>>                 but it seems they weren't recorded, and I've also
>>                 raised the issue with the DPV group directly too
>>                 (here <https://github.com/w3c/dpv/issues/53>)).
>>
>>                 Cheers,
>>
>>                 Pat.
>>
>>                 *Pat McBennett*, Technical Architect
>>
>>                 Contact  | patm@inrupt.com
>>
>>                 Connect | WebID
>>                 <http://pmcb55.inrupt.net/profile/card#me>, GitHub
>>                 <https://github.com/pmcb55>
>>
>>                 Explore  | www.inrupt.com <http://www.inrupt.com/>
>>
>>
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