NuGets Used 
NServiceBusThis sample demonstrates how to append the current username to outgoing messages and then how to extract that value when messages are handled.
Fake principal
For demonstration purposes, prior to sending a message, the Thread. will be replaced with a new instance. In a production scenario, the Thread. would be either the impersonated user from IIS or the current user sending a message.
var identity = new GenericIdentity("FakeUser");
Thread.CurrentPrincipal = new GenericPrincipal(identity, new string[0]);
var message = new MyMessage();
await endpointInstance.Send("Samples.UsernameHeader.Endpoint2", message)
.ConfigureAwait(false);
Custom header with a mutator
The recommended approach for capturing the current user is to create a transport mutator that extracts the current identity and then adds it to the header of every outgoing message.
Outgoing mutator
The outgoing mutator extracts Thread. and appends it to a message header.
public class UsernameMutator :
IMutateOutgoingTransportMessages
{
static ILog log = LogManager.GetLogger("Handler");
public Task MutateOutgoing(MutateOutgoingTransportMessageContext context)
{
log.Info("Adding Thread.CurrentPrincipal user to headers");
context.OutgoingHeaders["UserName"] = Thread.CurrentPrincipal.Identity.Name;
return Task.CompletedTask;
}
}
Register the Mutator
endpointConfiguration.RegisterComponents(
registration: components =>
{
components.ConfigureComponent<UsernameMutator>(DependencyLifecycle.InstancePerCall);
});
The Handler
From within a handler (or saga) this value can be used as follows:
public class HandlerUsingCustomHeader :
IHandleMessages<MyMessage>
{
static ILog log = LogManager.GetLogger("HandlerUsingCustomHeader");
public Task Handle(MyMessage message, IMessageHandlerContext context)
{
var headers = context.MessageHeaders;
var usernameFromHeader = headers["UserName"];
log.Info($"Username extracted from header: {usernameFromHeader}");
return Task.CompletedTask;
}
}
