Request service by type

[philarcher]

I have looked through the issues and can't find one to match this - sincere apologies if I've missed it and this is a duplicate.

In section 4.1.1 there's a note that points to a 5 year old email from @dlongley raising the possibility of a DID resolver returning info about a service identified by type rather than by ID. @ChristopherA was not supportive!

However, we use exactly this kind of request in a GS1-Conformant resolver. That is, you can request a particular type of associated resource. We use link relation types for this and have a simple parameter of linkType so that https://id.gs1.org/01/09506000164908?linkType=gs1:certificationInfo redirects to a resource that, in this case, gives you a load of certificates related to the product identified by the GTIN 9506000164908. https://id.gs1.org/01/09506000164908?linkType=gs1:sustainabilityInfo redirects to the recycling info and so on. (the gs1 prefix refers to our namespace. The set of link types we define is managed under our standards process).

This is done by leveraging the Linkset, as defined by RFC9264 and you can get the whole linkset with curl -H "Accept: application/linkset+json" https://id.gs1.org/01/09506000164908.

What happens if you have multiple target resources of the same type? Step forward HTTP Response code 300 :-) We've implemented this in the open source version of the resolver but it's not in the production service yet so don't go trying it.

I'm not suggesting a wholesale adoption of this approach in DID Resolution, merely pointing out that requesting a resource by type is useful and has been thought about and engineered in a nearby context. If there is support within the WG for identifying service endpoints by type, the basic approach might be useful.

No one here will care but the use of RFC9264 and the linkType parameter to control resolver behavior is included in ISO/IEC 18975, currently at FDIS stage (Final Draft International Standard) which means that, unless something goes horribly wrong, it will be an ISO/IEC standard before the end of the year. Of more importance here is that it's cited multiple times in the UN Transparency Protocol work being led by Steve Capell. What that work calls an Identity Resolver, or, informally, a link resolver, has this kind of thing in mind.

[peacekeeper]

I remember this discussion and agree with the rationale. In addition to the work you mention, discovering services by type also has been supported by certain other (historical) identifier resolution mechanisms in the past, e.g. Yadis and XRI Resolution.

So I would support introducing a "serviceType" parameter in DID Resolution, either in the spec itself, or via an extension.

[pchampin]

This was discussed during the did meeting on 10 October 2024.

View the transcript

DID Resolution Issue/PR Processing

burn: Contact the chairs if anyone would suggest an improvement

markus_sabadello: let's start with new issues

<markus_sabadello> https://github.com/w3c/did-resolution/issues?q=is%3Aopen+is%3Aissue+label%3Apending-close

markus_sabadello: first with pending close issues

burn: note that, in the agenda email, we listed these issues.
… We'll be using this process until the end of the thursday meeting to object to the close.

<TallTed> I strongly recommend such searches be ordered by "least recently updated" to keep the churn active, e.g., https://github.com/w3c/did-resolution/issues?q=is%3Aopen+is%3Aissue+label%3Apending-close+sort%3Aupdated-asc

burn: the point is, we'll review these quickly today, but the expectation is that you are too look for these in the agenda and speak up or comment in the issue if you have an objection
… so we will not be spending time unless there is a concern (as a general rule)

<markus_sabadello> w3c/did-resolution#57

markus_sabadello: Proposal to rename one of the resolution functions
… Resolve and ResolveStream
… This issue is a proposal to rename ResolveStream. That's already happened. I posted a comment 2 weeks ago. No further discussion

burn: any objections to closing?

markus_sabadello: I'll close them after the call

<markus_sabadello> w3c/did-resolution#30

markus_sabadello: Issue 30, several years old. Has to do with dereferencing discussion at TPAC
… "The result of dereference can be a DID document, but it can also be something else"
… Looking at this issue after a long time, I think the current specification addresses this. I see 3 thumbs up to that comment.
… So, if no objections, we'll be closing this.

<markus_sabadello> w3c/did-resolution#29

markus_sabadello: also several years old, about the definition of the term did resolver.
… In the current specification, both terms are defined formally in terminology section. Also two thumbs up.
… Any objections?

<markus_sabadello> w3c/did-resolution#21

markus_sabadello: Issue 21 about removing the term DID Reference from DID core to DID Resolution.
… I think this is now obsolete. We don't use that term in any spec.
… Same discussion was also in did-core, which was closed. So I think this one can be as well.
… Any objections?

<markus_sabadello> w3c/did-resolution#11

markus_sabadello: All methods must have a name of at least three characters.
… This seems like a DID Core issue, not in DID Resolution
… Similar issue in DID-core, which has also been closed.
… For all of these issues, it seems straightforward to close them.
… Since they are older issues, we may not be getting engagement from the initial poster, but unless there are objections, seems like we should close

decentralgabe: If we mark it pending close and give it a week, that would address the older participants

burn: requirements vary from group to group. In past groups, we've made the point to actively reach out by email and ask for engagement. Then you can comment that in the issue.
… so ping in the issue, then email, then document that email in the issue.
… That let's us show we've done what we can to address the concerns of the original poster
… For these, I think we're good, but going forward that's a nice improvement to our process

burn: you have 10 more minutes if you like

<markus_sabadello> https://github.com/w3c/did-resolution/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22

markus_sabadello: one other thing. A few issues are tagged as "Good First Issue"
… Two of them have been assigned. One has not.
… These are a good way to contribute, especially if you might not be familiar with deeper technical issues.
… We'll try to find more like that and encourage PRs
… A few that might be ready to close

<markus_sabadello> w3c/did-resolution#23

markus_sabadello: Issue 23 is about result of dereferencing

<manu> JoeAndrieu: Looking at the backlog. There is an opportunity here to make a distinction -- how we talk about a DID with and without a trailing slash... but I don't know if that helps us. I need to look at this in more detail, it's five years old, we can close it, if problem still exists, we can raise a new issue again.

<manu> markus_sabadello: I think this might be obsolete by now?

<manu> JoeAndrieu: Yeah, sounds like it might be.

<manu> markus_sabadello: We will have until next call to look at it or raise a new issue if this comes back.

<manu> JoeAndrieu: Sounds good to me.

manu: I'm wondering what is the ... I'm fine with closing it. I'm wondering where did we land?
… the response from a resolver is a resolution result, which might contain a did document?
… Is that where we landed?

markus_sabadello: that's right the resolution response might contain a did document, but dereferencing might return something else

manu: i think it's already addressed (as opposed to an older issue that isn't valid)

markus_sabadello: this was from when we didn't have a did resolution result, we were just returning DID documents
… That has been addressed

<JoeAndrieu> +1

manu: +1

markus_sabadello: also to be aware of, from discussions at TPAC, when we talked about path, query, and fragment parts.
… we talked about different patterns in the past and how much of that should be in the resolution spec itself or in did core, or in both.
… If people come up with certain features that use the path or query string, how does that fit in and where does it get specified?

<markus_sabadello> w3c/did-resolution#85

markus_sabadello: There are two open issues for new DID parameters with certain functionality

<markus_sabadello> w3c/did-resolution#90

markus_sabadello: The first introduces version-type the second XYZ as parameters
… Please comment about where these should go and whether or not it should be did-method-specific or standardized across methods

burn: ok, you have about another 5 minutes if you'd like

markus_sabadello: ok. I'm wondering if we can merge that pull request

<markus_sabadello> w3c/did-resolution#89

markus_sabadello: or if anyone has new thoughts about the discussion we had about primary resource and secondary resource
… there is an open PR where I tried to improve the headings
… to help with that. I'm wondering if people have opinions.
… I would actually prefer not to merge because it makes the headings longer
… But the algorithm talks about dereferencing the primary resource and secondary resource
… This PR adds explanation to the headings

manu: I think it is unfortunate that the initial wording was primary and secondary resource, as that is so abstract it is confusing.
… +1 to comment about section titles get hard

<TallTed> +1 to manu's suggestion

manu: maybe we can call it derereferencing a DID? or a #fragment
… +1 to not merge this, but maybe we can have did document and fragment as the terms

markus_sabadello: there is something that right now is called a primary resource.
… there needs to be a name for what you get when you dereference the did document
… For example, dereferencing the DID URL resource may be a better phrase

manu: yes. that was my thinking. Name the types of things you can dereference.
… A use case where you get a DID Document. A case where you dereference a fragment in a resource. And a third case where it's neither of those.
… Related Resource? (Not suggesting that, but if we name it, it will help)

markus_sabadello: this needs to be extensible. we can't imaging all the things they dereference to.
… but i think we can use better terms than Primary & Secondary. I'll try to do that.

<manu> JoeAndrieu: I would like to try my hand at writing this PR, don't know when I'm going to get to it, but want to help.

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[wip-abramson]

I also support a "serviceType" parameter for DID resolution.

I think it is both useful and broad enough to be worth including in this spec. DID Core defines services and all services must have a type.