Weaker Consistency Models & CRDTs

This lecture covers advanced topics in Distributed Shared Memory such as the need to trade off consistency under network partitioning as well as a special class of problems that can be used for replicating data services in a coordination-free manner. Conflict-free Replicated Data Types is a novel approach used to satisfy strong eventual consistency in an asynchronous, arbitrarily partitioned network of servers. State-based CRDTs (CvRDTs) build on the notion of a join semilattice to offer commutativity of monotonic updates whereas, operation-based CRDTs (CmRDTs) lift monotonicity to stronger model requirements. Finally, we also discuss and put into perspective the rest of the topics we are going to investigate in this course such as Consensus and Two Phase Commit. [Slides Download Slides]