title: MassTransit Send to Existing Exchange
body: <p>So I'm adding MassTransit to an existing project that was just using the RMQ client before. </p>
  
  <p>I'm trying to create a send only bus that binds to an existing exchange. However, when I try to send the message I get an error about the exchange type being "fanout" but the existing type is "topic" and I'm not sure how to specify that it should either be "topic" or that it shouldn't try to create the exchange at all and just use what is there.</p>
  
  <p>Topology: 'import' (exchange) -> 'import' (queue)</p>
  
  <p>Setup:</p>
  
  <pre class="lang-cs prettyprint-override"><code>    Bus.Factory.CreateUsingRabbitMq(
                      cfg =&gt;
                      {
                          cfg.UseNLog();
  
                          var host = cfg.Host(serverName, vhost,
                              options =&gt;
                              {
                                  options.Username(userName);
                                  options.Password(password);
                              });                    
                      });
  </code></pre>
  
  <p>Execution:</p>
  
  <pre class="lang-cs prettyprint-override"><code>    var ep = bus.GetSendEndpoint(new Uri($"rabbitmq://{userName}:{password}@{serverName}/{vhost}/{queue}")).Result;
  
                      ep.Send&lt;ImportMessage&gt;(CastMessage&lt;ImportMessage&gt;(message),
                          cfg =&gt;
                          {
  
                              cfg.SetRoutingKey("import");
                          }).Wait();
  </code></pre>
  
  <p>Command :</p>
  
  <pre class="lang-cs prettyprint-override"><code>    public class ImportMessage 
      {
          public ImportMessage()
          {
              Parameters = new List&lt;KeyValuePair&lt;string, string&gt;&gt;();
          }
  
          public List&lt;KeyValuePair&lt;string, string&gt;&gt; Parameters { get; set; }
          public string Endpoint { get; set; }
  
          public Guid Id { get; set; }
          public string Type { get; set; }
          public DateTime Expiration { get; set; }
      }
  </code></pre>