Coordination Service

It must have become evident by now that coordination is a central aspect of distributed systems.

Even though each component of a distributed system might function correctly in isolation, one needs to ensure that they will also function correctly when operating simultaneously. This can be achieved through some form of coordination between these components.

Coordination as an API

As illustrated in the chapter about consensus, this coordination can be quite complicated with many edge cases. Consequently, implementing these coordination algorithms on every new system from scratch would be inefficient and would also introduce a lot of risk for bugs.

On the contrary, if there was a separate system that could provide this form of coordination as an API, it would be a lot easier for other systems to offload any coordination function to this system.