Re: [dnssd] SRP Update - removing individual services (draft-ietf-dnssd-srp-06)

[Jonathan Hui <[e-mail]>]

On Sat, Dec 19, 2020 at 7:34 AM Kangping Dong <[e-mail]> wrote:

>
> In section 2.3.1. Validation of Adds
> <https://www.ietf.org/archive/id/draft-ietf-dnssd-srp-07.html#name-validation-of-adds>,
> we have:
>
>  SRP Updates consist of a set of *instructions* that together add or
>> remove one or more services.
>
> Each instruction consists either of a single add, a single delete, or a
>> delete optionally followed by an add.
>
> When an instruction contains a delete and an add, the delete MUST precede
>> the add.
>
>
> What is the use case of the "single add"? To my understanding,  the
> "delete + add" pattern is
> for resetting the service to our current SRP update. So the "single add"
> pattern is for updating
> the existing service, for example, adding one more AAAA RR, right?
>
> I think, for most SRP clients, it will be more convenient for them to
> track all IP Addresses and
> always update with the whole IP addresses list rather than depending on
> this "update" model
> and register the addresses separately. The server, I think can also be
> simplified. Thoughts?
>
> Another issue with this sentence is that, the Service & Host Description
> Invalidation requires:
>
>> exactly one "Delete all RRsets from a name" RR,
>
> Seems disallowing the "single add" pattern?
>

I believe the "single add" refers to a given instruction in the SRP Update.
Section 2.3.1.1 Service Discovery Instruction allows exactly one "Add to an
RRSet".

Maybe the "Validation of Adds" section name should be updated given that
the draft now supports "remove-only" instructions?

--
Jonathan Hui