title: NServiceBus sending information when a subscriber subscribes
body: <p>I'm just getting started with NServiceBus and I've got a very basic implementation up and running - much like the PubSub sample application.</p>
  
  <p>What I want to do is to send some information when a subscriber subscribes.</p>
  
  <p>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.</p>
  
  <p>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.</p>
  
  <p>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 <code>IMessage</code>.</p>
  
  <p><em>NOTE: I do also wish to use this information to then filter the messages NServiceBus sends to subscribers, but I thought I would <a href="https://stackoverflow.com/questions/6592556/nservicebus-filtering-messages-to-subscribers">post that as a separate question</a>.</em></p>