[Ndn-interest] Basic Query about Dual Names for one Content

Syed Hassan Ahmed s.h.ahmed at ieee.org
Thu Jul 21 01:16:11 PDT 2016

Thanks Dr. Alex and Prof. Lixia for the replies that actually helped me in
reshaping my query.

I am foreseeing an example scenario, where we have a vehicle (c) moving
from San Francisco (location X) to Los Angeles (location Y). Now in this
new city, a user wants to watch the recent news bulletin on his/her vehicle
On Board Unit screen. Previously, at location X, the vehicle (c) was using
hierarchical naming prefixes in the Interest packet to look up and retrieve
the content, for example:

Unique NONCE: vid/sf/breakingnews/date/10pm/chunk ID... (Interest Type 1)

Now quoting Dr. Alex, "If there are two producers that can serve data
packets under the same prefix, then forwarding system can choose either of
them.  If data cannot be retrieved from one, the forwarding may try
alternative path."
Will it be okay to assume that globally the name prefixes will be
identical? For example, at Location Y, the local users are using the
following prefix to retrieve the same content,

Unique NONCE: vid/sf/breakingnews/date/2200/chunk ID... (Interest Type 2)

Since the vehicle (c) is not aware of this changed prefix, how it can be
the provider of this content/chunk? Somehow, this vehicle needs to be
informed about the changed pattern of content prefix. Is the responsibility
of application then? I see this example, as two different name prefixes for
the same content.

When this vehicle receives an Interest of Type 2 with a unique Nonce Value
{to avoid Interest Looping}, due to a different presentation of Time or any
information within the prefix, vehicle (c) will not be able to forward the
required Data. If it would be, how?

Best Regards,
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
*Syed Hassan Ahmed *(하산)
Kyungpook National University,
Daegu City, Republic of Korea.
Cell: +82-10-9883-0786

On Thu, Jul 21, 2016 at 4:34 PM, Lixia Zhang <lixia at cs.ucla.edu> wrote:

> On Jul 21, 2016, at 12:18 AM, Syed Hassan Ahmed <s.h.ahmed at ieee.org>
> wrote:
> Respected NDN Community,
> Can we have two names for one Content? Let's say, we consider
> heterogeneous naming schemes, that have been applied at two different
> locations (X, Y) and the nodes are mobile (lets say Vehicles). Now when a
> node from location X moves into the range of location Y? How the NDN
> router/node resolves this issue? May be my question is a bit ambitious,
> however, I believe that one content can have multiple names. I understand
> the concept of NONCE somehow, but NONCE can be applied to two different
> names for the same content?
> 1/ yes a single piece of content can have multiple names.
> However every name should name a unique piece of content.
> 2/ There can be applications that name content based on locations.
> generally speaking, content names are not location-specific.
> 3/ in your above example: do vehicles X and Y carry an identical piece of
> content?
> If so, that content can have its own name, independent from the locations
> of X or Y, there is no issue whether X and Y are far apart or close to each
> other (this could lead you to a different question: if a name is not
> location-dependent, how NDN forwarders find the content: some discussions
> here: http://named-data.net/publications/survey_mobility_support_ndn/)
> 4/ "nonce" is not relevant to the above discussions; it's used to mitigate
>  interest looping.
> my 2 cents,
> Lixia
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