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Subject: Re: [wsn] Use case for double opt-in and other mechanisms forpreventing unwanted subscriptions
Thanks for the clarification. I'm still not sure what other message
exchanges between NP and consumer there might be. We only define one,
namely notify, and that only if useNotify is true. I think the key point of WSN is its third-party nature. The Subscribe MEP between Subscriber and Producer contains a pointer (EPR) to the Consumer, and the rest of the message flow happens between Producer and Consumer. Intuitively, this seems different from a case where the Consumer makes a request to the Producer and gets a response. Does that apply to what you're saying? I'm afraid we're going to end up talking in circles around each other if we're not careful. Tom Maguire wrote: Forgive my tortured english in the last post clarification below. Problems cannot be solved at the same level of awareness that created them. —Albert Einstein T o m M a g u i r e STSM, On Demand Architecture Poughkeepsie, NY 12601 David Hull <dmh@tibco.com> wrote on 11/22/2004 04:20:07 PM:Tom Maguire wrote: In double opt-in the consumer knows about the subscriber,should have been two sentences; comma should have been a ? so it should have read "In double opt-in the consumer knows about the subscriber? I believe the consumer would just know about the producer."No.agreeFirst, DOI is a message exchange between producer and consumer. The subscriber is not involved at all. Second, in the typical use case, the consumer may or may not know the identity of the subscribing entity. DOI applies in either case. I believe it would just be the producer? No. Generally something other than the producer (or consumer) is making the subscription, and the producer has no way of knowing a priori whether the subscription is appropriate. Nevertheless how is this any different from any other message exchange on the consumer? I'm not sure what this means. In the case I have in mind, the consumer is not a web service at all in the usual sense (yes, that is still covered by WSN).What I meant was; why is the 'notify' message exchange being treate differently then any other message exchange between the producer and the consumer w.r.t. auth?Tom Problems cannot be solved at the same level of awareness that created them. —Albert Einstein T o m M a g u i r e STSM, On Demand Architecture Poughkeepsie, NY 12601 David Hull <dmh@tibco.com> wrote on 11/22/2004 03:47:29 PM: Tom Maguire wrote: Is it not sufficient that security assertions or claims about the sender handle this? Why is the 'notify' MEP (as opposed to all the other MEPs the Notification consumer exposes) given special treatment in this regard? I do not understand why composition with WS-Security does not handle the requirement. What security assertions would handle the case where a consumer does not even know the subscriber exists? Tom Problems cannot be solved at the same level of awareness that created them. —Albert Einstein T o m M a g u i r e STSM, On Demand Architecture Poughkeepsie, NY 12601 David Hull <dmh@tibco.com> To 11/22/2004 03:07 wsn@lists.oasis-open.org PM cc Subject [wsn] Use case for double opt-in and other mechanisms for preventing unwanted subscriptions The Use Case: Because subscriptions may be made by a third party on behalf of the actual consumer, there must be some means of ensuring that the consumer only receives notifications it is interested in. There are many possible relationships among the subscriber, producer and consumer. For example The subscriber is provably the same entity as the consumer. The producer should accept any subscription from the consumer on its own behalf. The subscriber, producer and consumer are all in the same isolated environment and implicitly trust each other. Again, there is no need to restrict subscription. The consumer has supplied the subscriber with a secure token (which the NP is able to recognize) authorizing it to subscribe on the consumer's behalf. The NP should reject subscription requests without proper authorization. The consumer does not know the subscriber even exists, but might be interested in some unsolicited subscriptions. It is thus up to the producer to determine interest, generally by sending a test message under the double-opt-in pattern. Either of the previous cases may apply. The producer should look for the appropriate secure token, and if it's missing, ask the consumer via double-opt-in. A notification producer may impose a quota on subscriptions directed toward a given consumer (perhaps because the consumer asked it to). In this case, a given subscription may either succeed or fail depending on what other subscriptions are open. Clearly, many more variants are possible. Discussion: In cases where the producer must query the consumer before beginning the subscription, arbitrarily much time may pass between the subscription request and the definitive answer. This asynchronous reply would best be handled through a callback mechanism, but we would probably rather not build this into the core subscribe exchange. In the case of secure tokens, it might make sense for the subscriber to be able to submit and verify a token for a particular consumer once (in the context of a secure connection) instead of passing it with every subscribe request. It would be desirable to push all such message exchanges out of the core Subscribe request/response. This is one driver behind having the subscriber and producer be able to first negotiate a "destination" cookie and then use that cookie in the actual subscribe request. Naturally, this is not the only way to cover these use cases. > |
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