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    <p>With regard to publishing events from different endpoints, I think you're getting a little too caught up in the concept of an event being published from one service. That's true only in the logical sense - one event should be fully owned by one <em>logical</em> service, however <em>a logical service can be made up of many endpoints</em>.</p> <p>An event is not really published from a queue. When you think of the queue that an event is published from, what you really are talking about is the input queue where you send subscription requests for that event.</p> <p>So, you can have multiple endpoints all publishing the same event, as long as the subscription requests for that event all go to the same place.</p> <p>This is commonly the case, for instance, in a bulk vs. priority scenario, where you have two endpoints handling the same command (and then publishing the same event) except one is bulk with a long SLA, and the other has a much shorter SLA - maybe it's a big customer, or the command is coming from an actual human user waiting for a response. QueueA and PriorityQueueA both process the same command and publish the same event, but QueueA handles the subscriptions, so both processes "publish from" QueueA.</p> <p>That said, have you tried just letting multiple threads access the aggregate roots? Even with some contention, you may find that with a small number of retries it may not be as contentious as you might think. I have some fairly contentious processes in production with NServiceBus and although I see the occasional evidence of contention as an exception in the log, with 5 retries I never have any of those progress to the error queue.</p> <p>-- More recently, the second-level retries feature has been added which further decreases the chance of a message ending up in the error queue.</p> <p>If there is that much contention, another strategy might be to maintain an in-memory list of aggregate roots currently being operated on, and then if a message comes in that should be "locked out" just call <code>Bus.HandleCurrentMessageLater()</code> to stick that message back on the end of the queue.</p>
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    1. USUdi Dahan
    1. USDavid Boike
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    1. COThanks for the suggestions. I will get stuck into poc's provide feedback on progress. the Bus.HandleCurrentMessageLater() is getting me thinking. I should be able to work with that.
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      1. USRoss Jones
    2. COJust a question on having a logical service with multiple endpoints. Does this mean that the subscribers would need to subscribed to the same event on both (all) endpoints?
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      1. USRoss Jones
    3. CONo, the subscribers subscribe from (or rather, send the subscription requests to) the one logical authoritative source. That's where the subscription storage occurs. Multiple *physical* endpoints then can publish the same event as one unified *logical* publisher.
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