If I understand the concept of "content-id" correctly,Van Jacobsen and his team at Xerox-PARC are working on such globally unique, time-invariant content identifiers as we speak...."google" for "content-centric networking"
Jim On May 1, 2009, at 12:53 PM, Eric Burger wrote:
I think such a proposal would require a globally unique and time invariant content ID. That sounds challenging at best.On May 1, 2009, at 12:36 PM, Y. R. Yang wrote:Hi All, I found the discussion related with content ID interesting.Pushing upper layer information, in particular, content ID, into ALTO, according to my perspective, is to make it possible to turn an ALTO serverinto a session tracker so that it may take on additional potentialfunctions (depending on the format of the content ID) including content discovery (e.g., discover popular contents, notify caches), peer discovery(e.g., allow caches to register availability, return peers that arequesting peer does not know but ALTO server knows), and load balancing (e.g., the discussion on re-balancing). This email thread is discussingabout using it for rights management. I have no problem in adding an optional Content ID.But we need to keep in mind that providing the aforementioned functionsmay lead to a substantially more complex ALTO server architecture and semantics. I am particularly not clear about the statement that it is better for ALTO to provide information in the context of a particularcontent/swarm/channel (identified by a content ID in an ALTO query). Whatis the semantics/meaning that the ALTO info returned is adapted to aparticular content/swarm/channel? There can be many types of contents, e.g., file (BT block scheduling vs E2dk which uses a priority queue), livestreaming, VoD, VoIP, game. Different applications/variants will have their specific requirements/secret sauce for constructing peercommunication patterns. A query may be issued in a particular context,e.g., a seeder is looking for leechers or a leecher is looking for seeders. An application may use a lot more information (e.g., who aresources, who are seeders, upload/download capacity, buffer status, playout delay) to construct peer communication patterns. ALTO network informationis just one of the many inputs. Are we talking about designing anomnipotent ALTO server that functions as a universal application tracker?To make progress, follow the end-to-end design principle, and implementmodular/reusable design, I feel that we should first design the mostbasic, reusable ALTO component, whose function is just to provide simple,useful network information service, which is likely to be contentindependent. Then we can talk about more extensions. Content protection(e.g., content ID as access control token), content discovery (e.g.,mapping from a content ID to a list of servers), content notification tocaches, cache integration, session tracking, peer selection should be independent services, should ALTO provide some of them. The protocols(e.g., ALTO/P4P InfoExport interface descriptor) I have seen so far arequite extensible to accommodate new services. Richard On Thu, 30 Apr 2009, 3:58pm -0700, Richard Bennett wrote:As long as ALTO is defined as a service that maps a content ID to a collection of paths, it seems to me that it's piracy-neutral. I'm disturbed by a system that is passed a collection of paths and asked to rank them, as that would seem to have a definite pro-piracy bias. But I agree with Nick (I think) that a system that accepts a transient content ID and returns a list of paths is neither pro-piracy or anti-piracy. The rights management function can be layered on top of ALTO, as I think it should be, as a kind of DNS- for-content that takes some sort of textual description of the content and returns an identifier that ALTO can then use to guide toward the best paths. The higher level function - the content mapper - can be developed independent of IETF guidance and in accordance with some sort of deal between content producers and network operators. The content mapper is where the rights management goes,not in ALTO. RB Nicholas Weaver wrote:On Apr 30, 2009, at 2:19 PM, DePriest, Greg (NBC Universal) wrote:Thanks to Enrico and Nicholas for providing additional background andexplanations. The key point of disagreement seems to be that adding a contentprotection requirement to ALTO would "hugely complicate and compromisethe design of ALTO."I'm not an expert in such matters, have very limited exposure to thearea, and can't help but wonder if that is, in fact, correct. Was there a serious investigation or did someone simply do a back-of-the-envelope analysis.For me, its "Intuition backed up by a threat analysis and usage cases":We have legitimate uses which requires ID churn: its the only way to guarantee that a rebalancing is fresh. Especially since nodes churn all thetime, and ALTO may not have notification when nodes leave.We have legitimate uses which require IDs to be arbitrary (rather than representative hashes): ALTO is not just for file distribution, but other P2P optimization (eg, optimizing for low latency for DHTs) where hashesdon't have meaning. ALTO doesn't want to deal with particular P2Pprotocols, which all may have different representations of what data or blocks are. And doesn't want to deal with colliding namespaces fromdifferent P2P programs. Thus defining ID as a UUID or other opaque identifier means ALTO doesn't have to deal with these problems.We have legitimate uses which require IDs to be creatable at-will by any party: Otherwise, ALTO becomes an admission only system which limitsutility.Yet all three decisions (allowing churn, opaque-data IDs, at-will ID creation) and there becomes an easy countermeasure to ANY system predicated on "block bad IDs", as long as that system has a slower response time than the P2P network you are trying to prevent optimizing its communication, and you can't do "only allow good IDs" if IDs are creatable at-will by anyparty.And "if a defense has a trivial countermeasure, don't bother deploying it".Thus this means the only way to make ALTO "content protecting" is to remove one of those three constraints. But all three features are very valuable ina localization service.Additionally, there is a large bias in the network community in general to be "content neutral". Any time you cease to be content neutral on the technical level, it must necessarily impose constraints and costs on thesystem. _______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto_______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto_______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto_______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
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