| layout | docs |
|---|---|
| title | At-least-once Delivery |
| permalink | /at_least_once_delivery/ |
| redirect_from | /At-least-once_Delivery.html |
{: .patternintent} In case of failures that lead to message loss or take too long to recover from, messages are retransmitted to assure they are delivered at least once.
{: .patternstart} ------------- | ------------- ![At-least-once Delivery]({{ "/icons/at_least_once_delivery_icon.png" | prepend: site.baseurl }}) | How can communication partners or a Message-oriented Middleware ensure that messages are received successfully?
Sometimes, message duplicity can be coped with by the application using a Message-oriented Middleware. Therefore, for scenarios where message duplicates are uncritical, it shall still be ensured that messages are received.
For each message retrieved by a receiver an acknowledgement is sent back to the message sender. In case this acknowledgement is not received after a certain time frame, the message is resent.
![At-least-once Delivery]({{ "/sketches/at_least_once_delivery_sketch.png" | prepend: site.baseurl }})