Back to the Future: Rethinking Endorsement in Order-Execute Blockchains
A new consensus design embeds transaction approval directly into blockchain ordering, cutting wasted compute by up to 10x in high-traffic financial applications.
The Thesis
Most enterprise blockchains make every node execute every transaction before deciding which ones are valid — a process that wastes enormous effort when many transactions conflict with each other. This paper proposes FlexTender, a design that folds the approval step (called endorsement) directly into the consensus protocol, so conflicting or unauthorized transactions are filtered out before anyone wastes time executing them. The target audience is permissioned blockchains — private networks used by banks, regulators, and large enterprises, where you know who the participants are but still need fine-grained control over who can authorize what. The catch: FlexTender is built on top of a specific consensus protocol called Tendermint, so its portability to other blockchain stacks is unproven, and the evaluation uses a single synthetic workload derived from Ethereum's USDT stablecoin traffic.
Catalyst
DeFi workloads — where thousands of users race to interact with the same financial contracts simultaneously — have exposed a fundamental scalability flaw in existing enterprise blockchain designs. The Hyperledger Fabric approach (execute first, order second) was designed for general enterprise workflows, not high-contention financial trading, and abort rates in those conditions have become a recognized production problem. ChainMaker, the platform this paper targets, is a Chinese national blockchain infrastructure project that has reached a scale where these inefficiencies now have measurable economic cost.
What's New
The dominant alternative is Hyperledger Fabric's execute-order-validate (EOV) model, where every participating node speculatively runs a transaction, collects signatures (endorsements), and only then submits it for ordering — meaning wasted computation is baked into the design. Most other blockchains, including ChainMaker, use a simpler order-execute model where transactions are ordered first and executed second, but this model has never supported flexible per-contract approval policies. FlexTender takes the order-execute architecture and embeds endorsement checks directly into the Tendermint Byzantine fault-tolerant consensus rounds, adding zero extra message-passing in the normal (non-faulty) case while still enforcing flexible approval rules.
The Counter
The 10.6x throughput claim sounds impressive but rests on a single workload — a replay of Ethereum USDT transactions — against a simulated EOV baseline rather than a production Hyperledger Fabric deployment. Synthetic benchmarks tuned to one traffic pattern routinely fail to generalize: a mixed workload with lower contention might shrink that gap dramatically. FlexTender is also tightly coupled to Tendermint, which means any blockchain not already using that consensus protocol would need significant re-engineering to adopt it, limiting the addressable market. The paper acknowledges that censorship resistance — a core promise of decentralized systems — depends on careful endorsement policy design, but does not formally prove that FlexTender cannot be abused by a coalition of endorsers to selectively block transactions. Finally, the entire framing assumes permissioned blockchains will remain the dominant enterprise architecture, a bet that is far from settled as public L2 rollups with compliance layers begin to eat into that market.
Longs
- CANG (Canaan Inc.) — Chinese blockchain/ASIC infrastructure adjacent to national blockchain initiatives
- HBAR (Hedera, OTC) — competing enterprise DLT network that faces same throughput bottlenecks
- BRPHF (Brookson Group, OTC) — proxy for Chinese fintech infrastructure buildout
- BKCH (Global X Blockchain ETF) — broad exposure to enterprise blockchain infrastructure
Shorts
- Hyperledger Fabric ecosystem vendors (IBM Blockchain, Oracle Blockchain Platform) — their EOV architecture is explicitly argued to be inferior for high-contention financial workloads
- ConsenSys / Quorum — Ethereum-based enterprise blockchain whose throughput moat shrinks if order-execute systems can now match its flexibility
- R3 Corda — another permissioned blockchain whose endorsement model competes in the same regulated-finance segment
Enablers (Picks & Shovels)
- Tendermint BFT consensus library — the foundational protocol FlexTender directly modifies
- ChainMaker open-source platform (chainmaker.org.cn) — the production system used for empirical testing
- Ethereum USDT transaction datasets — the workload replay used to benchmark throughput claims
- Hyperledger Fabric — the EOV baseline against which FlexTender is compared
Private Watchlist
- ChainMaker (Beijing Zhongguancun Blockchain Industry Alliance) — the direct deployment target of this research
- Tendermint / Ignite (now part of Informal Systems) — maintainers of the consensus layer FlexTender extends
- Ant Group blockchain division — major Chinese permissioned blockchain operator with similar DeFi scaling needs
- Conflux Network — Chinese public blockchain with regulatory alignment and enterprise permissioned ambitions
Resources
The Paper
Due to regulatory compliance and governance management, modern (permissioned) blockchains require flexible endorsement, which allows the endorsement policy for each contract or state object to be individually defined. To enable flexible endorsement, Hyperledger Fabric employs an execute-order-validate (EOV) paradigm, in which transactions first undergo speculative execution and endorsement, and are only then ordered and validated. Meanwhile, most blockchain systems, including the platform targeted in this work (i.e., ChainMaker), still follow a conflict-free order-execute framework. We argue that the EOV paradigm still faces several limitations, notably high abort rates in high-contention workloads such as those in Decentralized Finance (DeFi). To avoid refactoring our system and better suit DeFi applications, we try to integrate flexible endorsement into the classical order-execute architecture and accordingly propose a new framework. The key challenge is to deterministically remove problematic transactions from an ordered list, while preserving censorship resistance and decentralization for the remaining ones. We instantiate this framework on top of Tendermint, a seminal Byzantine fault-tolerant (BFT) protocol adopted in our system, and thereby propose FlexTender. By elegantly embedding endorsements into consensus, FlexTender incurs no additional messaging overhead in the normal case. Empirical evaluation using an Ethereum USDT workload demonstrates that FlexTender achieves up to $10.6\times$ speedup in throughput over an EOV simulation on the same platform.