In this chapter, we considered the inevitable failure of our software and how NServiceBus can help us to be prepared for it. You learned how NServiceBus promises fault tolerance within every message handler so that messages are never dropped or forgotten, but instead retried and then held in an error queue if they cannot be successfully processed. Once we fix the error, or take some other administrative action, we can replay those messages.

In order to avoid flooding our system with useless messages during a failure, you learned how to cause messages that lose their business value after a specific amount of time to expire.

Finally, you learned how to build auditing in a system by forwarding a copy of all messages for later inspection, and how to properly deal with the challenges involved in calling external web services.

In this chapter, we dealt exclusively with NServiceBus endpoints hosted by the NServiceBus Host process. In the next chapter, we will explore in detail how NServiceBus...