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Subject: What's the difference between a distributor and a subscription manager?
The model we have now relies on a NotificationProducer which acts as a factory for SubscriptionManagers. The factory method (Subscribe) may take an open-ended set of policy/parameter elements, and the SM itself may support arbitrary additional methods beyond the basics. The model I am proposing shifts the variability onto the (optional) distributor role. The syntax and semantics of the Subscribe operation are fixed, except for the extensibility point for filtering (or not-a-filtering). Distributors are just consumers as far as the core is concerned. We recognize a special case where distributor EPRs are produced and specially treated by the NP itself, but this is not required and, depending on the particular scenario, may co-exist peacefully with garden-variety consumers. The SM itself would support only a minimal set of operations, perhaps as little as get* and destroy. Similarly, the SM's properties are reduced, probably to as little as filtering parameters and consumer(distributor) endpoint. The cost of this is an extra message exchange for creating a distributor (which may or may not be reused for multiple subscriptions) and an extra EPR to keep track of. This would only be incurred if the base semantics are not enough. In particular, the "dumb devices on an isolated network" case remains simple.
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