Re: [core] PubSub - Questions round 1

[Ari Keränen <[e-mail]>]

Hi Jim,

Here's finally answers to some of your questions.

> On 14 Sep 2017, at 7.10, Jim Schaad <[e-mail]> wrote:
> 
> 1  I am not clear what the visibility of the intermediate subtopic notes
> should be.  Should these nodes appear in the link list when doing a GET on
> the root of the pub-sub tree?  Should these nodes appear when doing a
> discovery on /.well-known/core?

I think the explicitly created topics should be visible in discovery. However, this includes the "main topics" created with CREATE interface. Perhaps the sub-topics under a main topic could be hidden from the root discovery since they can be discovered from the main topic.

But would be great to hear more opinions on this.

> 2.  I would appreciate a discussion for section 5 (resource directory) on
> what the trade-offs for publishing items into a resource directory?  What
> sets of nodes does it make sense to publish vs not publish - topics of
> discussion would include intermediate nodes and max-age for nodes that might
> disappear quickly.

I think lots of this is going to be implementation dependent. We could perhaps discuss the benefits of sub-topics: that you can expose only the main topic(s), let client discover sub-topics if needed, and this way save bandwidth on discovery is there are lots of sub-topics under different main topics. I'll make a PR out of this.

> 3.  When doing discovery, I am not sure if you examples are correct.  My
> understanding is that since a URI path is being returned as part of the link
> format rather than a full path, the client is supposed to interpret this
> value using the GET path as the context of the path.   This would be rule c
> of section 2.1 of RFC6690.  This rule seems to have been modified for the
> /.well-known/core to say only use the scheme + authority and ignore the path
> to the resource.  However, I do not believe that this rule is suspended in
> this case.  This means that the return value for figure 4 would be
> "</currentTemp>;rt=temperature;ct=50".   Do you believe that I am wrong?

I think you're correct here. But I wonder how can we generate then topics outside of the ps -- or if we want to do that. Let's discuss tomorrow.

> 4.  Just because I don't understand.  In RFC 6690  - what is the origin for
> rule (b)?  I would have thought this was the target URI value itself, but in
> that case I would expect that (b) should be before (a) if it has a schema
> and thus is an absolute path.

I suppose it's the link authority. But let's check with Zach ;)


Cheers,
Ari