The CAP theorem, introduced by Brewer and formalized by Gilbert and Lynch, is often considered foundational for distributed systems engineers. However, it is mostly irrelevant for those building cloud-style systems. It becomes more significant for developers of intermittently connected applications, like IoT or mobile apps. The theorem states that systems can have both strong consistency and availability as long as a quorum of replicas is available. In practice, most cloud systems manage network partitions effectively, ensuring high availability and strong consistency. CAP is more relevant for engineers working in intermittently connected environments. The challenge is to move beyond CAP and explore other trade-off spaces like CALM, RUM, or PACELC.
https://brooker.co.za/blog/2024/07/25/cap-again.html