Two-phase commit (2PC) is widely used in distributed databases to ensure atomicity of distributed transactions. Conventional 2PC was originally designed for the shared-nothing architecture and has two limitations: long latency due to two eager log writes on the critical path, and blocking of progress when a coordinator fails. Modern cloud-native databases are moving to a storage disaggregation architecture where storage is a shared highly-available service. Our key observation is that disaggregated storage enables protocol innovations that can address both the long-latency and blocking problems. We develop Cornus, an optimized 2PC protocol to achieve this goal. The only extra functionality Cornus requires is an atomic compare-and-swap capability in the storage layer, which many existing storage services already support. We present Cornus in detail and show how it addresses the two limitations. We also deploy it on real storage services including Azure Blob Storage and Redis. Empirical evaluations show that Cornus can achieve up to 1.9X latency reduction over conventional 2PC.

Inter-vehicle communication among great deals of vehicles plays an important role in providing a high level of safety and convenience to drivers. Geographic routing protocol has been identified to be suited as a result of the special nature of vehicular ad hoc networks (VANETs), such as high dynamic mobility and large network size. Although there is considerable functional research about geographic routing, the security aspects have not been vastly concentrated on so far. While selecting every hop, the performance and security can be impacted severely by false position, because of the position information importance for geographic routing. Through taking advantages of directional antennas, we propose a novel detection mechanism capable of recognizing nodes faking about their positions in beacon message. By checking through which antenna (f-antenna or b-antenna) beacons are received, ones' neighborhood can be easily divided into two groups. In addition, compared with the detection rules, a node can efficiently detect the malicious nodes after exchanging neighbors grouping information with other vehicles. As the evaluation based on simulations shows, our position verification system can detect malicious nodes successfully and can prevent attacks on geographic routing by false position.