On Thu, Jul 18, 2013 at 12:34 PM, Wendy Roome <[email protected]>wrote:
> Unless I missed something, draft 17 allows an ALTO Server to provide more > than one full cost map resource for the same cost-type (and network map). > What would that mean? I can think of a couple of possibilities: > To set the stage properly, the protocol draft never prohibited two cost maps of the same cost type with different data even before draft -17. > > * That should be illegal. > > > * The resources are equivalent, and they return the same cost map (at > least eventually :-)). The duplicates provide load balancing, so the > client should pick one randomly. > > * The resources return different cost maps. Eg, the server has several > different versions of one cost-metric, and they are distinguished by the > resource id. This implies that a filtered map service that offers a > multi-version cost-metric should have a 'uses' attribute to indicate which > cost-map resource it's based on. > > I think the last interpretation will cause a lot of confusion. Invent a > new cost-metric name instead! > > As for the other two, I have a mild preference for outlawing duplicates, > but I'd support the separate-but-identical interpretation if the rest of > you like that idea. > I agree with disallowing duplicates, with the caveat that extensions can introduce distinguishing attributes in the future [will need to update the draft to document how that is done]. For example, imagine an extension introduced a 'granularity' attribute; it would be good to allow ALTO clients to have routingcost at multiple granularities in the same IRD. Rich > > - Wendy Roome > > > _______________________________________________ > alto mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/alto >
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