On Fri, Jul 11, 2014 at 1:18 PM, Wendy Roome <[email protected]> wrote:
> 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. > > Catching up on the discussions... My understanding is that Wendy and Jan are making the same conclusion. Jan: "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." >From an OO design point of view, I see JSON as a base type, and JSON Patch as a base function on the base type. Network/Cost maps are derived types that may also override the patch method to be more efficient. I can see another design that for the same type, one instance Network/Cost map can be patched using JSON Patch, for example, when it is small, while another instance of the same type can use the more efficient encoding. Hence, we have the effect of prototype (JS) based derivation system. The exact method can be announced, easily, in IRD. Richard > 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 > > > > > -- -- ===================================== | Y. Richard Yang <[email protected]> | | Professor of Computer Science | | http://www.cs.yale.edu/~yry/ | =====================================
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