Using NServiceBus with multiple application both act as Publisher and Subscriber

Question

Hi,

I'm trying to use NServiceBus to make 4 applications communicating together.

All these applications have to act as Publisher and Subscriber.

The only way i founded ti get it workiing is to create a "master" queue named Server, on which MessageEndpointMappings in all applications configuration is mapped to, but i think it's not the good way ...

So how should i configure NServiceBus on all these application to get this working ?

Application 1 :

  <MsmqTransportConfig InputQueue="MyApp1" ErrorQueue="Errors" NumberOfWorkerThreads="1" MaxRetries="5"/>
  <MsmqSubscriptionStorageConfig Queue="Subscriptions" />
  <UnicastBusConfig>
    <MessageEndpointMappings>
      <add Messages="MyApp.Messages" Endpoint="Server" />
    </MessageEndpointMappings>
  </UnicastBusConfig>

Application 2 :

  <MsmqTransportConfig InputQueue="MyApp2" ErrorQueue="Errors" NumberOfWorkerThreads="1" MaxRetries="5"/>
  <MsmqSubscriptionStorageConfig Queue="Subscriptions" />
  <UnicastBusConfig>
    <MessageEndpointMappings>
      <add Messages="MyApp.Messages" Endpoint="Server" />
    </MessageEndpointMappings>
  </UnicastBusConfig>

Application 3 :

  <MsmqTransportConfig InputQueue="MyApp3" ErrorQueue="Errors" NumberOfWorkerThreads="1" MaxRetries="5"/>
  <MsmqSubscriptionStorageConfig Queue="Subscriptions" />
  <UnicastBusConfig>
    <MessageEndpointMappings>
      <add Messages="MyApp.Messages" Endpoint="Server" />
    </MessageEndpointMappings>
  </UnicastBusConfig>

Application 4 :

  <MsmqTransportConfig InputQueue="MyApp4" ErrorQueue="Errors" NumberOfWorkerThreads="1" MaxRetries="5"/>
  <MsmqSubscriptionStorageConfig Queue="Subscriptions" />
  <UnicastBusConfig>
    <MessageEndpointMappings>
      <add Messages="MyApp.Messages" Endpoint="Server" />
    </MessageEndpointMappings>
  </UnicastBusConfig>

Answer 1

NServiceBus prefers you follow the pattern of a particular message type being published by one service only. Typically you will have a 'messages' assembly for each service, eg:

  <MsmqTransportConfig InputQueue="MyApp1" ErrorQueue="Errors" NumberOfWorkerThreads="1" MaxRetries="5"/>
  <MsmqSubscriptionStorageConfig Queue="MyApp1Subscriptions" />
  <UnicastBusConfig>
    <MessageEndpointMappings>
      <add Messages="MyApp2.Messages" Endpoint="MyApp2" />
      <add Messages="MyApp3.Messages" Endpoint="MyApp3" />
      <add Messages="MyApp4.Messages" Endpoint="MyApp4" />
    </MessageEndpointMappings>
  </UnicastBusConfig>

If you want to publish the same message type from all four applications, you can Bus.Send() the message to a central event publisher service, which could then Bus.Publish() it.