Index-based routing model for multi-facet proxy architectures in EVM blockchains

Abstract

Multi-facet proxy architectures address the limitations of monolithic smart contracts by distributing protocol logic  among multiple implementation contracts while preserving a common external interface and storage context. Existing  standardized architectures primarily use function selectors as routing identifiers, coupling facet selection with  behavioral identification and consequently introducing selector management, collision considerations, and function 

level routing metadata. This study analyzes these limitations and introduces an index-based routing model that  represents facet identity independently from function identity. The proposed model appends a routing index to calldata  outside the Application Binary Interface-encoded function call, allowing the router to select a facet directly while  preserving conventional function selectors for compatibility with existing Ethereum interfaces and tooling. The model is  applied to an upgradeable multi-facet proxy architecture specified by the proposed standard and realized by the Cento  Proxy reference implementation. The resulting architecture provides facet-level routing granularity, removes selector specific facet management and selector-collision constraints, supports selector-independent facet entry points, and reduces the routing-related implementation surface. The reference implementation is evaluated against the Diamonds reference implementation under equivalent conditions using gas and bytecode measurements. The results demonstrate  substantial reductions in facet-management and introspection costs, while maintaining near-identical standard routing performance and introducing only a small overhead for protocol-to-protocol routing caused by on-chain construction of  routing metadata. The complete protocol also requires substantially less deployment cost, while the reference  implementation contains considerably less runtime bytecode. The study demonstrates that separating facet identity from  function identity provides an alternative routing abstraction with measurable architectural and efficiency benefits while  remaining compatible with the established Ethereum Virtual Machine ecosystem.