SDOA: A scalable and trustworthy oracle architecture for heterogeneous blockchains

As a key technology for bridging blockchain data silos, blockchain oracles now face challenges in heterogeneous-chain compatibility, dynamic scalability of off-chain services, and the reliability of off-chain data. This paper proposes a Scalable Distributed Oracle Architecture (SDOA), which incorporates a master-slave multi-chain oracle identity management scheme that enables trustworthy registration, authentication, and synchronization among blockchain systems, oracle nodes, and off-chain extended services. The multi-chain access middleware hides the heterogeneity of underlying chains, supports the decoupling of on-chain and off-chain components, and allows multiple heterogeneous blockchains to access the oracle network dynamically. Based on the number of participating nodes and available extended services, SDOA further defines four service patterns—SNSS, SNMS, MNSS, and MNMS—enabling users to customize service policies on demand. We evaluate SDOA from four perspectives: functional validity, resource cost, system performance, and fault tolerance. The results show that SDOA provides favorable compatibility and configurable trade-offs across service patterns under the tested settings, while also revealing the overhead introduced by larger oracle clusters and multi-source aggregation.