NServiceBus 在订阅者订阅时发送信息 [英] NServiceBus sending information when a subscriber subscribes

问题描述

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 - 很像 PubSub 示例应用程序.

I'm just getting started with NServiceBus and I've got a very basic implementation up and running - much like the PubSub sample application.

我想做的是在订阅者订阅时发送一些信息.

What I want to do is to send some information when a subscriber subscribes.

例如，假设我有一个包含分类产品的数据库.我的发布者将每 N 秒检查一次数据库，并在新产品添加到数据库时发送消息.

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.

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是否有该类别中的新产品.

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.

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 IMessage.

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.

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.

推荐答案

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得回调.如果您想在订阅请求中包含一些额外的元数据，您需要使用 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.

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