Replicated Convergent Data Containers

Managing replicated data in distributed systems that is concurrently accessed by multiple sites is a complex task, because consistency must be ensured. In this paper, we present the Replicated Convergent Data Containers (RCDCs) - a set of distributed data structures that coordinate replicated data and allow for optimistic inserts, updates and deletes in a lock-free, non-blocking fashion. It is crucial that continuous data harmonization among containers takes place over time. This is achieved by a synchronization mechanism that is based on a technique called Operational Transformation (OT) which continously reconciles diverging containers. A generic architecture is placed on top of this underlying synchronization mechanism that allows to realize a multitude of different RCDCs. Two container specializations are presented: (a) the linear container that organizes data in an ordered sequence, (b) the hierarchical container that organizes the data in an n-ary tree.