[Ict4d] Fwd: Is DTN dead?

Tue Jun 9 17:27:59 SAST 2015

Hi Alette

While I was at UCSB we built a few solutions to deal with the upload
problem. One was a localized cloud that reroutes the stored object to
a local store when the user is for example using Facebook to share an
object with another local user in a village - this is for the scenario
where you have an Internet gateway being shared by a large higher
speed local wireless network and suers want to share content with each
other - Dwesa in the Eastern Cape cape would a good example of this.

The other interesting project we did was creating a local cache for
storing a youtube upload - sending this and your OAUTH authenticatoin
details to another server located in the US which is owned by the
project and is kind and friendly and doesn't throw you off when your
round trip time starts getting too high and then pushing the file to
youtube from the US server using the stored OAUTH authentication
details. OAUTH is just a very widely used authentication mechanism
used by Facebook, Google, Dropbox etc.

Regards
David

___________________________

David Johnson
Principal Researcher
Networks and Media group
Meraka, CSIR
Adjunct Senior Lecturer
ICT4D, Computer Science Department
University of Cape Town

On Tue, Jun 9, 2015 at 5:08 PM, Hussein Suleman <hussein at cs.uct.ac.za> wrote:
> hi Alette
>
> timeouts depend mostly on where people are trying to upload to.
>
> traditional "cloud" Web services in some up-north countries are notorious
> for setting timeouts based on local audiences who are connected over high
> speed networks. this works well to optimize the resources they need on the
> servers but it does not work well where legitimate uploaders have slower
> speeds.
>
> the solution is local sites/storage with different parameters for timeouts
> or a definition of timeout that will not kill a connection with a steady
> trickle but will kill connections with long delays in any data being
> transferred. the absolute wrong definition of timeout (that i personally
> experienced in an open source tool last month) was one where there was a
> fixed time limit for all uploads, irrespective of size/speed!
>
> from a system design perspective, a leaner design for online data transfer
> services (such as polled async tcp connections) will work in all scenarios
> while the quick-and-dirty solutions (such as resource-hungry java servlets,
> stock apache cgi) is what gets us in trouble. better system design will help
> everyone :)
>
> ttfn,
> ----hussein
>
> =====================================================================
> hussein suleman ~ hussein at cs.uct.ac.za ~ http://www.husseinsspace.com
> =====================================================================
>
>
> On 09/06/2015 15:01, Alette Schoon wrote:
>>
>>
>> Hi all
>>
>> I tried to read the paper, but I'm afraid I did not understand much of
>> it. Does this in any way relate to how people's phones time out when
>> they try and upload large audio or video phones on the mobile internet?
>> Because I'm trying to find some references that will explain why this
>> happens among my hip hop artists in my study.
>> Any explanations will be appreciated.
>> All the best
>> Alette
>>
>> Quoting Melissa Densmore <mdensmore at cs.uct.ac.za>:
>>
>>> I would hesitate to say "dead" but you are right, there hasn't been that
>>> much work done recently in the space - pretty much since Keshav switched
>>> over to environmental sensing.  Even my Ghana Telemedicine Network stuff
>>> was done back in 2008.  The main difficulty I think we struggled with was
>>> that it takes a ton of work to get a stable DTN going - and often by the
>>> time we got something working, mobile phones or DSL would arrive and
>>> immediately displace our efforts.  At the same time, it's been 10
>>> years and
>>> some parts of Africa are still largely unconnected.  I don't think the
>>> applicability of DTN has reduced - but the number of researchers
>>> looking to
>>> leverage it in isolated places has greatly reduced.  It's possible
>>> that the
>>> DTN reference architecture is simply too much overhead for rural
>>> deployments, with no clear benefits (e.g. interoperability, etc) for
>>> using
>>> it. Tons of people use informal DTNs (flash drives, Netflix, media
>>> kiosks)
>>> without using a formal network architecture worthy of a paper.
>>>
>>> Some other relevant papers:
>>> Luk, Rowena, Melissa Ho, and Paul M. Aoki. "Asynchronous remote medical
>>> consultation for Ghana." *Proceedings of the SIGCHI conference on human
>>> factors in computing systems*. ACM, 2008. http://arxiv.org/pdf/0801.1927
>>>
>>> Ho, Melissa, and Kevin Fall. "Poster: Delay tolerant networking for
>>> sensor
>>> networks." *Proc. of IEEE Conference on Sensor and Ad Hoc Communications
>>> and Networks*. 2004.
>>>
>>> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.59.3330&rep=rep1&type=pdf
>>>
>>>
>>>
>>> Digital Study Hall was also originally a DTN-based system, most recently
>>> presented in 2012, but focus has shifted to questions of interaction
>>> rather
>>> than content delivery
>>> Richard Anderson, Chad Robertson, Esha Nabi, Urvashi Sahni, and Tanuja
>>> Setia. 2012. Facilitated video instruction in low resource schools. In
>>> *Proceedings
>>> of the Fifth International Conference on Information and Communication
>>> Technologies and Development* (ICTD '12). ACM, New York, NY, USA, 2-12.
>>> DOI=10.1145/2160673.2160675 http://doi.acm.org/10.1145/2160673.2160675
>>>
>>> There's also dtn stuff on SaamiNet (2009)
>>> Doria, Avri, Maria Uden, and D. Pandey. "Providing connectivity to the
>>> saami nomadic community." *generations* 1.2 (2009): 3.
>>>
>>> David - I would pose this question on the gaia mailing list, which
>>> includes
>>> a lot of the people that originally worked on the DTN architecture for
>>> both
>>> space and rural motivations.
>>>
>>> Melissa
>>>
>>> On Mon, Jun 8, 2015 at 3:56 PM, David Johnson <djohnson at csir.co.za>
>>> wrote:
>>>
>>>> Hi all
>>>>
>>>> One of my lectures in my Net4D honours modules is on the use of DTN as
>>>> a connectivity option for poorly connected areas. The slides I have
>>>> are mostly about historical work such as DakNet (2004) and KioskNet
>>>> (2007)
>>>>
>>>> My sense is that this research has mainly continued to have traction
>>>> in the realm of Vehicular networks and space networks and that its no
>>>> longer considered as a serious contender for rural/poorly connected
>>>> regions ... there are some interesting new developments that mix
>>>> social networks and delay tolerant networks - but they seem mostly
>>>> like playful ideas than something to take seriously.
>>>>
>>>> Then you get weirdness like this 2014 paper from Disney on a DTN
>>>> solution for mico-entrepeneurs using  DTN-enabled projects (cinemas in
>>>> a backpack) - the example being moving content between urban areas in
>>>> Pretoria and an under-served ex-homeland North of Pretoria - there is
>>>> not one African researcher on the paper ... I think I will use this as
>>>> a prime example of what goes wrong when communities don't participate
>>>> in the research process.
>>>>
>>>> So DTN for rural/under-serviced areas - dead?
>>>>
>>>> David Johnson
>>>> Principal Researcher
>>>> Networks and Media group
>>>> Meraka, CSIR
>>>> Adjunct Senior Lecturer
>>>> ICT4D, Computer Science Department
>>>> University of Cape Town
>>>>
>>
>>
>>
>>
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