Highly-available and consistent group collaboration at the edge with colony

Abstract

Edge applications, such as gaming, cooperative engineering, or in-the-field information sharing, enjoy immediate response, autonomy and availability by distributing and replicating data at the edge. However, application developers and users demand the highest possible consistency guarantees, and specific support for group collaboration. To address this challenge, Colony guarantees Transactional Causal Plus Consistency (TCC+) globally, strengthened to Snapshot Isolation within edge groups. To help with scalability, fault tolerance and security, its logical communication topology is forestlike, with replicated roots in the core cloud, but with the flexibility to migrate a node or a group. Despite this hybrid approach, applications enjoy the same semantics everywhere in the topology. Our experiments show that local caching and peer groups improve throughput and response time significantly, performance is not affected in offline mode, and that migration is seamless. CCS Concepts: • Computer systems organization → Peer-to-peer architectures; • Networks → Cloud computing; • Information systems → Key-value stores; Distributed storage; • Computing methodologies → Distributed algorithms.

Transactional-Turn Causal Consistency

“…consistency model): under serializability, transactions execute (logically) in lockstep; whereas under snapshot isolation (SI), a transaction does not block but operates upon a private snapshot of the database [4]. The lesser-known Transactional Causal Consistency (TCC) is fully asynchronous, as it also supports concurrent writes [3,14]. In summary, TCC is also asynchronous, isolated and atomic; developers may leverage concurrency without having to worry about memory interference, locking or deadlocks.…”