On Dependability of Heterogeneous Distributed Oracle System in Blockchain

Both blockchain and oracle are among key technologies which are leveraged in Web 3.0 to empower the internet industry. Oracle aims to provision blockchain with real world data and support external connectivity for closed blockchain systems. Compared with a centralized oracle system, a distributed oracle system can tackle the issues of single point failure and untrusted data. This paper explores analytical modeling techniques to quantitatively study the dependability (availability and reliability) of the distributed oracle system with arbitrary number of heterogeneous oracle nodes. We first develop a Markov model to describe oracle system dynamics. Then we derive both the formula of system availability and the formula of mean time to failure (MTTF) to study the system reliability. The experimental results indicate 1) the system availability is mainly affected by mean node failure time when it is smaller than 10 days, 2) the system recovery ability has critical impact on availability, and 3) MTTF can be significantly improved by introducing more nodes.