[ndnSIM] Using the setExpiryTImer

Sun Nov 25 01:17:16 PST 2018

Hello, Pradhan

> On Nov 24, 2018, at 9:38 PM, Ashish Pradhan <ashishpradhan1162 at gmail.com> wrote:
> 
> Can't this be done simply by making a custom strategy and using the setExpiryTimer? If not, where is the setExpiryTimer useful?
> 
> In the documentation it is mentioned that "If the strategy wishes to collect responses from additional upstream nodes, it should invoke setExpiryTimer within this function to prolong the PIT entry lifetime. If a Data arrives from another upstream during the extended PIT entry lifetime, this trigger will be invoked again. At that time, this function must invoke setExpiryTimer again to continue collecting more responses." http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a97b4f1e5496c4dd08cc17b5d3d265f08 <http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a97b4f1e5496c4dd08cc17b5d3d265f08>
> 
> Shouldn't this simply work?
> 

Yes, this works if you only want to "prolong the PIT entry lifetime” and “collecting more responses” at this node.
But what you need is to continue forwarding data, which means the in-record of PIT entry should not be deleted.
In-records are deleted in the “Strategy::sendData” function, which is called by “Strategy::afterReceiveData” after “beforeSatisfyInterest”
So if you don’t want to hack NFD, you can override “afterReceiveData” and try to send Data with “m_forwarder.onOutgoingData” but not  “sendData”.

> On Sun, Nov 25, 2018 at 2:31 PM Lixia Zhang <lixia at cs.ucla.edu <mailto:lixia at cs.ucla.edu>> wrote:
> 
> 
>> On Nov 24, 2018, at 9:20 PM, Ashish Pradhan <ashishpradhan1162 at gmail.com <mailto:ashishpradhan1162 at gmail.com>> wrote:
>> 
>> No, the producers produces multiple data objects(not segmenting into multiple data packets). 
> 
> no difference: the producer knows how many total packets it produces.
> 

Could you please tell me whether the multiple data objects have the same name?
If their names are different, I think you can make it with out keep the PIT entry.

Best wishes,
Xinyu Ma.

> 
>> 
>> On Sun, Nov 25, 2018 at 2:15 PM Lixia Zhang <lixia at cs.ucla.edu <mailto:lixia at cs.ucla.edu>> wrote:
>> 
>>> On Nov 24, 2018, at 4:08 PM, Ashish Pradhan <ashishpradhan1162 at gmail.com <mailto:ashishpradhan1162 at gmail.com>> wrote:
>>> 
>>> Hi Xinyu,
>>> 
>>> Thank you for your reply.
>>> 
>>> I am fully aware of the One-Interest-One-Data behavior. However, I have a custom app(a producer) where it produces multiple data for a single interest.
>> 
>> I would like to better understand what is going on here: do you mean the producer app generates a data object which needs to be segmented into multiple data packets?
>> 
>> If so: yes one can find a way to hack the code to allow the bread crumb of one Interest to retrieve multiple data packets, but it is unclear to me a good idea to use across a network 
>> (one interest can retrieve the first data packet, which can carry "FinalBlockId" to inform the consumer how many more data packets to fetch).
>> 
>> Lixia
>> 
>>> Then I want all the produced data to reach the consumer. So for that, I am implementing a custom strategy where the PIT entry lifetime of the nodes are extended after it receives the first data from the producer. I have followed the ndnSIM API documentation for it. 
>>> 
>>> beforeSatisfyInterest documentation:
>>> http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a97b4f1e5496c4dd08cc17b5d3d265f08 <http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a97b4f1e5496c4dd08cc17b5d3d265f08>
>>> 
>>> setExpiryTimer documentation:
>>> http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a967ad88184231f79b245ce202e9d4ea7 <http://ndnsim.net/current/doxygen/classnfd_1_1fw_1_1Strategy.html#a967ad88184231f79b245ce202e9d4ea7>
>>> 
>>> Best regards,
>>> Ashish Pradhan
>>> 
>>> 
>>> 
>>> On Sun, Nov 25, 2018 at 2:21 AM Xinyu Ma <bitmxy at gmail.com <mailto:bitmxy at gmail.com>> wrote:
>>> Hello, Pradhan
>>> 
>>> I’m sorry I don’t understand why you want to extend the PIT entry’s lifetime and what you mean by “data response other than the first one”.
>>> NDN follows One-Interest-One-Data, so the PIT entry should be deleted after receiving the data.
>>> You can send another Interest if you still want the PIT entry to be there.
>>> 
>>> Best,
>>> Xinyu Ma.
>>> 
>>>> On Nov 24, 2018, at 6:20 AM, Ashish Pradhan <ashishpradhan1162 at gmail.com <mailto:ashishpradhan1162 at gmail.com>> wrote:
>>>> 
>>>> Hi all,
>>>> 
>>>> I am trying to use the setExpiryTimer to extend the PIT entry's lifetime. However the data response other than the first one is not being forwarded back to the consumer. I have included the setExpiryTimer in the beforeSatisfyInterest function as follows:
>>>> "NFD_LOG_DEBUG("beforeSatisfyInterest pitEntry=" << pitEntry->getName() <<
>>>>                 " inFace=" << inFace.getId() << " data=" << data.getName());
>>>> 
>>>>   this->Strategy::setExpiryTimer(pitEntry, ndn::time::milliseconds(100));"
>>>> 
>>>> Is there any thing that needs to be added?
>>>> 
>>>> After looking at the sendData function there is this line "pitEntry->deleteInRecord(outFace);". If it is deleting the inRecord how does the setExpiryTimer help to preserve the entry?
>>>> 
>>>> Best regards,
>>>> Ashish Pradhan
>>>> 
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>> 
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