Code walk-through
This sample shows how to define and exchange immutable messages between endpoints. Immutable messages can be defined as interfaces with only getters:
public interface IMyMessage
{
string Data { get; }
}
Or as classes with only getters and a non-default parameterless constructor:
public class MyMessage
{
public MyMessage(string data)
{
Data = data;
}
public string Data { get; private set; }
}
At startup the application creates two endpoint instances, a sender and a receiver. Both are configured to use Json.Net as serializer through the NServiceBus. package:
var endpointConfiguration = new EndpointConfiguration("Samples.ImmutableMessages.UsingInterfaces.Sender");
endpointConfiguration.UseSerialization<NewtonsoftJsonSerializer>();
endpointConfiguration.UsePersistence<LearningPersistence>();
var routingConfiguration = endpointConfiguration.UseTransport(new LearningTransport());
Sending messages
The sender endpoint allows to send messages to the receiver using either an immutable message defined as a class or one defined as an interface. In this latter case the sender endpoint defines an internal message class that implements the public, shared, interface:
class MyMessageImpl : IMyMessage
{
public string Data { get; set; }
}
The internal class is then used by the sender endpoint at dispatch time
var myMessage = new Messages.MyMessageImpl()
{
Data = data
};
return endpointInstance.Send(myMessage);
Receiving message
To receive an immutable message defined using one of the two presented techniques no special configuration is needed. The only requirement is a serializer capable, or configurable to do so, of deserializing objects using private setters and/or non-public parameterless constructors. The receiver endpoint defines regular message handlers:
public class MyMessageAsInterfaceHandler :
IHandleMessages<IMyMessage>
{
static ILog log = LogManager.GetLogger<MyMessageAsInterfaceHandler>();
public Task Handle(IMyMessage message, IMessageHandlerContext context)
{
log.Info($"IMyMessage (as interface) received from server with data: {message.Data}");
return Task.CompletedTask;
}
}
public class MyMessageAsClassHandler :
IHandleMessages<MyMessage>
{
static ILog log = LogManager.GetLogger<MyMessageAsClassHandler>();
public Task Handle(MyMessage message, IMessageHandlerContext context)
{
log.Info($"MyMessage (as class) received from server with data: {message.Data}");
return Task.CompletedTask;
}
}