Showing posts from October, 2021

Exactly-Once Delivery

Exactly-Once Delivery (EOD) is a very useful guarantee to have when designing a distributed system; being sure that no message is lost or delivered more than one time, despite all possible faults, makes the design of any distributed systems simpler. Intuitively, EOD is clear: we don’t want to lose or duplicate the data/operations. The exact definition, however, is not agreed upon in the community. As a result, there is a debate on whether EOD is possible or impossible to achieve. In this post, we focus on EOD, its possibility/impossibility, and what it really means in practice.