[Ndn-interest] Question regarding consistency

Lixia Zhang lixia at CS.UCLA.EDU
Mon Aug 24 12:36:33 PDT 2015

> On Aug 24, 2015, at 6:12 AM, aniesh chawla <chawla.aniesh at gmail.com> wrote:
> Hello Everyone,
> I have a very basic doubt which I could not resolve while reading documentation of NDN. I would like to also take this as research topic if my doubt is valid.
> The question is:
> How is the consistency of data maintained in the network? Since, NDN is "pull" based networking and lets say there is change in file version at one of the node and not in other nodes. I can see the this can be achieved through NDNFS, but still the other nodes will not have change in version of the file. So, how will the new node who is requesting for that file will get to know which version to ask for? If we use NDNS to resolve every such query and we use time stamp as version then also it should be propagated throughout the network? I also see that Chrono-sync does something like this but it has waiting timer for propagation delays. So either NDNS is talking to every node in the whole network or some other way.
> Is my understanding correct or am I missing something here?

Let me step up a level:
1/ in developing NDN applications, the first and most important thing is to get the naming design right.
If your files change over time, you would consider to put a version number as part of the file name to allow you to tell different versions.

2/ Keep in mind that NDN is a network protocol; each produced NDN data packet is immutable.  Therefore there is no "consistency" issue about "data maintained in the network".

3/ Maybe your question is about "how do end consumers learn that a new version of the file has been produced?"
- this question has nothing to do with NDNS (my view)
- there can be multiple solutions here, running Sync, periodically pull the file with the next version number, some notification service, etc.


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