Jan,
I think it is misleading to wait for ³incremental updates to be available
in ALTO². Incremental updates will never be available in ALTO as a whole.
Instead, incremental updates will be available for the various ALTO
services separately. Just the various ALTO services are independent (more
or less), incremental updates for those services will also be independent.
Providing incremental update for one ALTO service will not automatically
provide it for the others. Notice that in
https://datatracker.ietf.org/doc/draft-roome-alto-incr-updates/ the
incremental update mechanisms for network and cost maps are completely
separate, and an ALTO server can implement one without the other.
Put it another way: If incremental update for network & cost maps were
available right now, they would not provide incremental update for the
new ALTO services you proposed. You would still have to define incremental
update yourself.
And while I didn¹t look over the CDNI-FCI data in detail, it seemed like
it was a relatively small amount of data. 5kbytes, maybe 10k tops. After
all, the service just provides information for a few local servers, not
for the entire internet, doesn¹t it? And I suspect the
mean-time-between-changes is on the the order of minutes, not seconds. So
my guess is that downloading the full map whenever it changes costs (say)
5kbytes/5min. Incremental update might cut that to (say) 1kbytes/5min. But
is the hassle of incremental update really worth saving 4kb every 5
minutes?
- Wendy
On 07/11/2014, 04:50, "Jan Seedorf" <[email protected]> wrote:
>Wendy, Sebastian,
>
>I see your points. The thing that worries me is that one of the arguments
>_not_ to use ALTO for CDNI-FCI in the CDNI WG has been that it will take
>some time for incremental updates to be available for ALTO. We have
>always argued that incremental updates for ALTO are "on the way" (which
>indeed is/was the case). Now, from that perspective, if the "default"
>ALTO solution for incremental updates would only work for classic
>network/cost maps, and would not work for our ALTO CDNI FCI service, that
>is not desirable.
>
>On the other hand, there are some differences when using ALTO for CDNI
>compared to P2P that have implications on incremental updates: CDNI-FCI
>is CDN service provider to CDN service provider (so you can expect a high
>capacity link between the two); the number of PIDs in a CDNI FCI network
>map footprint is likely much smaller than 5000; the overall size of a
>CDNI FCI object-format-map is likely much, much smaller than a cost map
>for a large ISP. All of these differences actually imply that incremental
>updates are not so crucial for the CDNI case than for e.g. the P2P case:
>if a uCDN has e.g. 4 dCDNs, the overall amount of data being sent over
>the network is much smaller than if an ISP has 200.000 P2P users, so
>fetching the complete JSON object each time may be ok for CDNI-FCI.
>
>So we may have good arguments for saying ALTO network/cost map service
>has a specific incr. update solution, and ALTO CDNI FCI service uses JSON
>patch.
>
>I guess I would like to hear other opinions ...
>
>- Jan
>
_______________________________________________
alto mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/alto
