The fundamental theories of Distributed System are CAP, ACID and BASE:
- CAP:
- Consistency: Every read receives the most recent write or an error.
- Availability: Every request receives a non error response, without the guarantee that it contains the most recent write.
- Partition tolerance: The system continues to operate despite an arbitrary number of messages being dropped.
Distributed system only provides tow out of three features. So it is often a problem of choosing between consistency and availability. For example DynamoDb choose availability over consistency.
2. ACID:
- Atomicity
- Consistency
- Isolation
- Durability
ACID is usually mentioned in database transactions. For implementation, often use Two phase locking (2PL) and multiversion concurrency control (MVCC).
3. BASE
- Basically Available
- Soft state
- Eventually consistent
Base is eventual consistency in order to achieve high availability.
This blog introduce three basic models of distributed system: CAP, ACID, BASE. And this blog is a under category of distributed system.