ImmortalChopper: Real-Time and Resilient Distributed Transactions in the Edge-Cloud

Emerging applications in the areas of real-time Internet of Things (IoT) and edge technologies require fast processing and response times. This motivates the utilization of edge nodes for storing and processing data close to the user. In settings with a vast number of edge nodes, the state of the data is distributed across a large number of edge nodes. This makes it expensive to perform distributed transactions, as these transactions would span edge nodes that are connected via less reliable and relatively slow network infrastructure. It is prohibitive to use existing protocols like 2PC that require many rounds of communication across participants. In this paper, we propose ImmortalChopper, a distributed transaction processing protocol designed for the edge-cloud environment. The goal of ImmortalChopper is to provide One-Node Response (InResponse), a guarantee of transaction commitment by contacting only one node without waiting for coordination with the other nodes. To achieve this, we build on and extend the literature of transaction chopping and lazy replication. Transaction chopping breaks transactions into smaller hops. If the first hop commits, the rest of the transaction is guaranteed to commit, accomplishing the goal of 1n-Response. Each hop is replicated to tolerate temporary node failure, and we apply lazy replication on the first hop to maintain 1n-Response. However, combining transaction chopping and lazy replication without special care can lead to transactions operating on a stale state and potentially violating serializability. We present a new transaction chopping theory called ChopperGraph that integrates the notion of lazy replication and speculative execution. It ensures 1n-Response while preserving serializability. We evaluate ImmortalChopper on three applications, and the result shows that it achieves 1 n-Response in real-time and can quickly recover from node failure.