[Nfd-dev] expressInterest when Nack received without a NackCallback

[Thompson, Jeff]

> the library already have a knowledge that the interest will never be
>received.

Maybe the interest with the same nonce will never be received. But if the
network Nack is due to temporary congestion then the same interest will
work on the next retransmission (which the application should do after a
delay).



On 2016/4/27, 13:49:57, "Alex Afanasyev" <aa at cs.ucla.edu> wrote:

>
>> On Apr 27, 2016, at 1:31 PM, Thompson, Jeff <jefft0 at remap.ucla.edu>
>>wrote:
>> 
>> Hello.
>> 
>> A question came up while studying network Nack support in ndn-cxx.
>>Suppose someone has an application which calls expressInterest with only
>>the OnData and OnTimeout callbacks. Normally, if the library doesn¹t
>>call OnData, it calls OnTimeout after the interest lifetime.
>> 
>> However, if the library receives a network Nack, it calls OnTimeout
>>immediately, regardless of the interest lifetime. Could this cause
>>confusion? I ask because it¹s not deterministic whether the network will
>>reply with a Nack or not. If the application is not set up to handle
>>Nacks, would it be better to just let the interest time out, even if the
>>library receives a Nack?
>> 
>> Thanks for any feedback,
>> - Jeff T
>
>Of course it can cause the confusion.  Depending on what logic is set for
>onTimeout action, it may result in unnecessary retransmission.  It is not
>really better to "time out" when NACK is received, as the library already
>have a knowledge that the interest will never be received.
>
>---
>Alex