"In Event Sourced systems, Latency is feared by the Developpers, and Eventual Consistency is uncacceptable for Business"
Most of us have been taught that users want to see the result of actions in our systems immediately. And that therefore a typical transactional system is a must.
And so, we stopped thinking about time. And so, we stopped asking: * How long are you willing to wait * Does it make sense to show an immediate response
Event sourcing, and the associated use of CQRS (Command Query Responsibility Segregation) has put time back as a first class citizen in our systems. And made the need of discussions about latency explicit.
Latency and Eventual consistency is not a fatality. It is a matter of modelling. Modelling event streams.
This talk will explore an eventsourced subsystem, build for a government HR agency. The steps used to tame eventual consistency inside it. As well as those taken for integrating it into the whole Legacy system.
