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Architecture Overview

HAQQ is a scalable Proof-of-Stake blockchain that is fully compatible and interoperable with the Ethereum Virtual Machine (EVM). It is built using the Cosmos SDK which runs on top of the CometBFT (a fork of Tendermint Core) consensus engine, to accomplish fast finality, high transaction throughput and short block times (~2 seconds).

This architecture allows users to perform both Cosmos and EVM formatted transactions, developers to scale EVM dApps cross-chain via IBC, and tokens and assets in the network to come from different independent sources.

HAQQ enables these key features by:

  • Leveraging modules and other mechanisms implemented by the Cosmos SDK.
  • Implementing CometBFT's Application Blockchain Interface (ABCI) to manage the blockchain.
  • Utilizing geth as a library to promote code reuse and improve maintainability.
  • Exposing a fully compatible Web3 JSON-RPC layer for interacting with existing Ethereum clients and tooling (Metamask, Remix, Truffle, etc).

The sum of these features allows developers to leverage existing Ethereum ecosystem tooling and software to seamlessly deploy smart contracts which interact with the rest of the Cosmos ecosystem.

Cosmos SDK​

HAQQ enables the full composability and modularity of the Cosmos SDK. As a Cosmos chain, HAQQ is a sovereign blockchain with its own native token, that can connect to other chains through IBC. It includes standard modules from the Cosmos SDK, that work side to side with HAQQ-specific modules, built by the HAQQ core development team.

CometBFT & ABCI​

CometBFT consists of two chief technical components: a blockchain consensus engine and a generic application interface. The consensus engine ensures that the same transactions are recorded on every machine in the same order. The application interface, called the Application Blockchain Interface (ABCI), enables the transactions to be processed in any programming language.

CometBFT has evolved to be a general-purpose blockchain consensus engine that can host arbitrary application states. Since it can replicate arbitrary applications, it can be used as a plug-and-play replacement for the consensus engines of other blockchains. HAQQ is an example of an ABCI application replacing Ethereum's PoW via CometBFT's consensus engine.

Another example of a cryptocurrency application built on CometBFT is the Cosmos network. CometBFT can decompose the blockchain design by offering a very simple API (ie. the ABCI) between the application process and consensus process.

EVM Compatibility​

HAQQ enables EVM compatibility by implementing various components that together support all the EVM state transitions while ensuring the same developer experience as Ethereum:

  • Ethereum's transaction format as a Cosmos SDK Tx and Msg interface
  • Ethereum's secp256k1 curve for the Cosmos Keyring
  • StateDB interface for state updates and queries
  • JSON-RPC client for interacting with the EVM