Towards Saving Blockchain Fees via Secure and Cost-Effective Batching of Smart-Contract Invocations

Abstract

This paper presentsiBatch, a middleware system running on top of an operational Ethereum network to enable secure batching of smart-contract invocations against an untrusted relay server off-chain.iBatchdoes so at a low overhead by validating the server's batched invocations in smart contracts without additional states of user nonces. TheiBatchmechanism supports a variety of policies, ranging from conservative to aggressive batching, and can be configured adaptively to the current workloads.iBatchautomatically rewrites smart contracts to integrate with legacy applications and support large-scale deployment. We built an evaluation platform for fast and cost-accurate transaction replaying and constructed real transaction benchmarks on popular Ethereum applications. With a functional prototype ofiBatch, we conduct extensive cost evaluations, which showsiBatchsaves$14.6\%\sim {}59.1\%$Gas cost per invocation with a moderate 2-minute delay and$19.06\%\sim {}31.52\%$Ether cost per invocation with a delay of$0.26\sim {}1.66$blocks.