Regular Register: An Implementation in a Churn Prone Environment

Due to their capability to hide the complexity generated by the messages exchanged between processes, shared objects are one of the main abstractions provided to the developers of distributed applications. Among all the shared objects, the register object is fundamental. Several protocols have been proposed to build fault resilient registers on top of message-passing system, but, unfortunately, failure are not the only challenge in modern distributed systems. New issues arise from the dynamicity introduced in the system by the continuous arrival and departure of nodes (churn phenomenon). This paper addresses the construction of a single writer/multiple readers regular register in a distributed system affected by the continuous arrival/departure of participants. In particular, a general protocol implementing a regular register is proposed and feasibility conditions on the arrival and departure of the processes are given. Interestingly, the protocol is proved correct under the assumption that the constraint on the churn is satisfied.