MassTransit Messages

[Intro]

Messages are the backbone of MassTransit, without them there would not really be a need for the solution. Messages IMO should be a Verb. "Customer" is not a suitable message name as it has no intent, "NewCustomerCreated" is therefore a more suitable name. As far as MassTransit goes a message just needs to be a class that is marked as [Serializable]. For most scenarios is have encountered I actually want to track a specific message, i.e. I want to know its identity (which we will cover soon), so I have my message implement the interface "MassTransit.CorrelatedBy<T>" which gives the message a Correlation Id so I can track it. It is probably a good time to mention that messages are Immutable dumb DTO's. I have worked on several systems now that try to ignore this and every time it has ended in trouble. The message is a trigger, it should never be the entity you manipulating.

An Example from the MassTransit Pub/Sub Sample is below:

[Serializable]
public class RequestPasswordUpdate :
    CorrelatedBy<Guid>
{
    private readonly string _newPassword;
    private readonly Guid _correlationId;
       public RequestPasswordUpdate(string newPassword)
    {
        _correlationId = Guid.NewGuid();
        _newPassword = newPassword;
    }
    public string NewPassword
    {
        get { return _newPassword; }
    }
    public Guid CorrelationId
    {
        get { return _correlationId; }
    }
}

Using the correlation Id means that  later on when I want to listen for associated messages I can. This will be covered in [Consumers/Publishers]