NServiceBus Unit of Work For Multitenancy with Custom ORM

Question

Here are my parameters:

Simple NServiceBus Saga implementation using the default builder
In-house ORM on top of SQL Server
Multitenancy - I have two ASP.NET MVC 4 domains running on the same website, each with their own databases

We configure our ORM using a static method like so:

public class EndpointConfig: IConfigureThisEndpoint, IWantCustomInitialization {
  public void Init() {
    var bus = Configure.With()
      .AutofacBuilder()
      .UnicastBus().LoadMessageHandlers().DoNotAutoSubscribe()
      .XmlSerializer()
      .MsmqTransport().IsTransactional(true).PurgeOnStartup(false)
      .MsmqSubscriptionStorage()
      .Sagas().RavenSagaPersister().InstallRavenIfNeeded()
      .UseInMemoryTimeoutPersister()
      .CreateBus()
      .Start();

     SlenderConfiguration.Init(bus);
  }
}

public class SlenderCofnigruation {
  private static ORMScope scope { get; set; }

  public static void Init(IBus bus)
  {
    ORMConfig.GetScope = () =>
    {
       var environment = "dev";
       if (bus.CurrentMessageContext.Headers.ContainsKey("Environment"))
         environment = bus.CurrentMessageContext.Headers["Environment"];

       if (scope == null)
         scope = new SlenderScope(ConfigurationManager.ConnectionStrings[environment].ConnectionString);
      return scope;
    };
  }
}

This works fine in our single-tenant Beta environment - it's fine for that static scope to get re-used because the environment header is always the same for a given deployment.

It's my understanding that this won't work for the multitenant situation described above, because NServiceBus will reuse threads across messages. The same scope would then be used, causing problems if the message was intended for a different environment.

What I think I want is a single scope per message, but I'm really not sure how to get there.

I've seen Unit Of Work Implementation for RavenDB, and the unit of work implementation in the full duplex sample, but I'm not sure that's the right path.

I've also seen the DependencyLifecycle enum, but I'm not sure how I can use that to resolve the scope given the way I have to set up the GetScope func.

Obviously I have no idea what's going on here. Any suggestions?

Udi Dahan Udi Dahan · Accepted Answer · 2012-12-14T13:56:45

If you need to do something on a per-message basis, consider using message mutators (IMutateIncomingMessages) in addition to your unit-of-work management with some thread-static state.

NServiceBus Unit of Work For Multitenancy with Custom ORM

1 Answers