[Ndn-interest] nfd and iot?
Marc.Mosko at parc.com
Marc.Mosko at parc.com
Mon May 23 07:10:50 PDT 2016
While I agree that ICN can offer a lot of advantages over IP based IoT solutions, I do not think it’s quite so simple to use opportunistic caching as a replacement for something like an MQTT broker. The broker offers several processing features, like the QoS attribute and wildcarding subscriptions. Using opportunistic caching, consumers can miss publications if the cache gets evicted or maybe just due to adversarial timing of messages.
I looked at the poster, but was not able to determine if there was some mechanism you used beyond opportunistic caching and normal NDN data matching. I think there are some shortcomings to using only those mechanisms in a service that is supposed to deliver (perhaps reliably) all messages in a publication stream to all currently subscribed clients.
Depending on the timing of publications and Interests, a client could miss messages. For example, a sensor is publishing /sensor/1, /sensor/2, … /sensor/N. If a consumer is asking for these with exclusions and “left most child” to try to walk them in order, it could still miss one due to packet loss. Lets say it gets 1 … 10, then 11 is lost in network, so 12 is the “left most child” at the closest router. It would then skip to 12, and unless you do some recovery mechanism at the consumer, 11 is lost without even know it. If one is using timestamps or some other non-monotonic sequence number, then it would be very hard to know about the omission. Even without packet loss, one could still miss messages. If two consumers are pulling data but at slightly different rates, one could be on “10” and the other pulls “11” and “12” before the next interest from the first arrives. “12” is now the “left most child” so it would miss 11.
From: Ndn-interest <ndn-interest-bounces at lists.cs.ucla.edu> on behalf of "Mahmoudi, Charif (IntlAssoc)" <charif.mahmoudi at nist.gov>
Date: Monday, May 23, 2016 at 9:06 PM
To: "gabesilva2004 at yahoo.com" <gabesilva2004 at yahoo.com>, "ndn-interest at lists.cs.ucla.edu" <ndn-interest at lists.cs.ucla.edu>
Subject: Re: [Ndn-interest] nfd and iot?
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