title: activemq difference between durable subscriptions with and without retroactive mode
body: <p>I have just started using activemq, and I have a question about retroactive consumers, in order to enable this feature you need to have a durable subscription. But what is the difference of a durable subscription with and without retroactive enabled on the topic? the activemq doc says.</p>
  
  <p><a href="http://activemq.apache.org/retroactive-consumer.html" rel="nofollow">http://activemq.apache.org/retroactive-consumer.html</a>
  A retroactive consumer is just a regular JMS Topic consumer who indicates that at the start of a subscription every attempt should be used to go back in time and send any old messages (or the last message sent on that topic) that the consumer may have missed.</p>
  
  <p>about retroactive consumers. and for durable subscribers:</p>
  
  <p><a href="http://activemq.apache.org/how-do-durable-queues-and-topics-work.html" rel="nofollow">http://activemq.apache.org/how-do-durable-queues-and-topics-work.html</a>
  ...So for durable topic subscription, the JMS provider needs to be able to identify S when it shuts down and later on in the future reconnects, so it can know what messages to send to it while it was not running</p>
  
  <p>I dont really see any big differences between durable subscriptions with and without retroactive mode.</p>
  
  <p>Please explain thanks. </p>