[Ndn-interest] Freshness & Latest Content

Urs Schnurrenberger urs.schnurrenberger at unibas.ch
Thu May 3 15:33:14 PDT 2018

Hi Junxiao,

thanks for the answers and the link. I have a follow-up question:

What then happens when the (same as below) Interest
        /nytimes/frontpage | CanBePrefix=true | MustBeFresh=true
arrives at a cache with the sole content
        /nytimes/frontpage/addBanner/v23 | 60'000ms

According to prefix matching and a positive freshnessPeriod, will I receive the addBanner only and never the complete front page?

Best regards,

Von: Junxiao Shi <shijunxiao at email.arizona.edu>
Gesendet: Donnerstag, 3. Mai 2018 23:37
An: Urs Schnurrenberger <urs.schnurrenberger at unibas.ch>
Cc: ndn-interest at lists.cs.ucla.edu
Betreff: Re: [Ndn-interest] Freshness & Latest Content

Hi Urs

I have some conceptual questions about freshness and how to ask for latest content.

Imagine 2 properly versioned versions of /nytimes/frontpage (properly in the sense of “larger” version = “newer” version, according to [1]):
format : contentName | freshnessPeriod
/nytimes/frontpage/v100 | 100ms [stored at cache X somewhere between requester and producer]
/nytimes/frontpage/v105 | 300ms [stored at producer]

I assume that if a user does only know about the contentName (prefix), but not about the latest versionNumber, he/she asks for
Interest: /nytimes/frontpage | CanBePrefix=true | MustBeFresh=true

Yes, that's what consumer should ask for.

Question 1:
Is it correct that this Interest is satisfied by cache X because there is a prefix match on the contentName and a freshnessPeriod > 0?

Yes, X will return /nytimes/frontpage/v100 until it becomes non-fresh.

Question 2:
Assuming the answer to Q1 is ‘yes’ and that the reuqester does NOT know the latest versionNumber, is there really no possibility for the requester to get the globally latest version v105 directly from the producer?

It is possible but requires changes on producer. See https://redmine.named-data.net/issues/4396#note-1

Question 3:
Assuming that the requester KNOWS the latest versionNumber (from some miraculous oracle), I guess she/he can simply ask for (/nytimes/frontpage/v105 | CanBePrefix=false | MustBeFresh=true). Correct?

Yes, the Interest should have version number if the consumer knows it.

Yours, Junxiao
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