NServiceBus 在订阅者订阅时发送信息
我刚刚开始使用 NServiceBus，并且已经启动并运行了一个非常基本的实现 - 非常类似于 PubSub 示例应用程序。
我想做的是当订阅者订阅时发送一些信息。
例如，假设我有一个包含已分类产品的数据库。我的发布者将每 N 秒检查一次数据库，并在将新产品添加到数据库时发送消息。
但每个订阅者只对特定类别感兴趣，我想在他们订阅时发送该类别，以便发布者知道检查数据库中该类别的新产品。
类别是动态的，因此我无法为不同的类别创建不同的消息。因此，出于这个原因，我假设所有订阅者都必须订阅相同的已发布的 IMessage。
注意：我也希望使用此信息来过滤 NServiceBus 发送给订阅者的消息，但我想我会 将其作为一个单独的问题发布。
I'm just getting started with NServiceBus and I've got a very basic implementation up and running - much like the PubSub sample application.
What I want to do is to send some information when a subscriber subscribes.
For example, lets say I have a database with products that are categorized. My publisher will check the database every N seconds and will send messages when a new product is added to the database.
But each subscriber is only interested in a particular category and I want to send that category when they subscribe so that the publisher knows the check the database for new products in that category.
The categories are dynamic, so I can't create different messages for the different categories. So for that reason I assume that all the subscribers have to subscribe to the same published IMessage.
NOTE: I do also wish to use this information to then filter the messages NServiceBus sends to subscribers, but I thought I would post that as a separate question.
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您可以实现 IAuthorizeSubscriptions 接口，以便在订阅者请求订阅时在发布者处获取回调。如果您想在订阅请求中包含一些额外的元数据，则需要使用 Bus.OutgoingHeaders - 然后您可以在发布者处查看该信息并决定如何处理它。
You can implement the IAuthorizeSubscriptions interface to get a callback at the publisher when a subscriber requests to subscribe. If you wanted to include some additional meta-data in the subscription request, you'll need to use Bus.OutgoingHeaders - then you can look at that info at the publisher and decided what to do with it.
我已经有一段时间没有使用 NServiceBus 了，但我认为 NServiceBus 没有任何事件可以在订阅发生时通知您。
尽管如此，我认为您可能在一个过于精细的水平上接近您的解决方案。
您通常会订阅企业通常感兴趣的事件。在您的情况下，当添加新产品时。一个更简单的解决方案是简单地订阅
ProductAddedEvent并让您的订阅者忽略任何它不感兴趣的消息。自我推销警告！ :) --- 我这里有一个 FOSS ESB（仍然是 CTP）： http://shuttle.codeplex.com/< /a>
我们在总线的各个部分使用管道，您给了我一个在
StartupPipeline上包含SubscriptionRequested事件的想法。I haven't worked with NServiceBus for quite some time but I don't think NServiceBus has any events to notify you when a subscription has taken place.
Be that as it may I think you may be approaching your solution on a level that is too fine.
You usually subscribe to events that the business is typically interested in. In your case when a new product is added. A simpler solution would be to simply subscribe to say a
ProductAddedEventand have your subscriber ignore any messages that it is not interested in.Self-promotion warning! :) --- I have a FOSS ESB available here (still CTP): http://shuttle.codeplex.com/
We make use of pipelines for various parts of the bus and you have given me an idea to include a
SubscriptionRequestedevent on theStartupPipeline.