how-do-i-reply-to-a-message.md

title	summary	tags
How to Reply to a Message?	Answer a message using the Reply method on IBus.

The simplest way to reply to a message is using the Reply method on IBus, like this:

public void Handle(RequestDataMessage message)
{
    //Create a response message
    var response = new DataResponseMessage
    { 
        DataId = message.DataId,
        String = message.String
    };
    
    Bus.Reply(response); 
    //Try experimenting with sending multiple responses
    //Bus.Reply(response); 
    //Underneath the covers, this method sends a new message to the return address on the message being handled.
    //Bus.Send(Bus.CurrentMessageContext.ReturnAddress, Bus.CurrentMessageContext.Id, responseMessage);
}

You should only use a reply when you implement the Request-Response pattern (also called the Full Duplex pattern). In this pattern the originator of the message should expect a response message and have a handler for it. See the Full Duplex Sample provided with the install and the article How to Handle Responses on the Client Side for examples and more information.

When using the Publish-Subscribe pattern an endpoint handling an event shouldn't use Bus.Reply. This is because the publisher will not be expecting any reply and should not have a handler for it.