Glos cqrs

CQRS

CQRS is a simple pattern that strictly segregates the responsibility of handling command input into an autonomous system from the responsibility of handling side-effect-free query/read access on the same system. Consequently, the decoupling allows for any number of homogeneous or heterogeneous query/read modules to be paired with a command processor and this principle presents a very suitable foundation for event sourcing, eventual-consistency state replication/fan-out and, thus, high-scale read access. In simple terms: You don't service queries via the same module of a service that you process commands through. For REST heads: GET wires to a different thing from what PUT/POST/DELETE wire up to. - Clemens Vasters

Comments

I like the statement of Greg Young: "The creation of 2 objects where there previously was one." All the rest are side effects IMO - Tom Janssens