Data Bus

This smart contract functions as a communication channel on the blockchain, allowing for efficient message exchange between various services.

Features

• ability to send arbitrary events with arbitrary data
• minimalistic implementation
• low gas consumption
• does not require support and administration

How It Works

The smart contract uses a special kind of event, referred to as an "abstract event," which can be customized to carry different types of data under various event identifiers. This flexibility allows the system to handle multiple event types through a single unified mechanism.

Abstract Event Design

The event structure in the contract is defined as follows:

event Message(
    bytes32 indexed eventId,
    address indexed sender,
    bytes data
) anonymous;

The anonymous attribute in this event means it does not use the standard topic for the event signature as is typical in Ethereum events. Instead, it utilizes a manually specified eventId as the primary identifier. This design allows the system to abstract away from specific event types, enabling users to define and emit any event type based on this generic template. For more details on anonymous events, you can refer to the Solidity documentation.

Emitting Events

To emit an event, you first calculate the hash of your event signature (e.g., keccak256(bytes('SomeEvent(address,bytes)'))) which becomes the eventId. This identifier along with the data is then passed to the following function:

function sendMessage(bytes32 _eventId, bytes calldata _data)

This function takes the eventId and the data you want to transmit, and it logs the event on the blockchain. This method allows any user-defined event to be emitted using the Message event template, offering a flexible and powerful way to handle custom events.

Compatibility and Extensions

This setup is compatible with most Ethereum libraries, which handle the parsing of event data directly. If the event data requires specific types other than bytes, additional encoding steps may be necessary when processing or emitting events.

Additionally, to facilitate the use of this contract, we have developed DataBusClient. This client library provides methods for both reading and sending events using a human-friendly ABI format. Initially developed in TypeScript, it can be easily ported to other programming languages to meet diverse implementation needs.

You can familiarize yourself with the library implementation: library

Also with usage examples:

• Simple event monitoring
• Transaction spammer with arbitrary events
• Implementation of tests

Building and testing

Create .env file

CHIADO_BLOCKSCOUT=
GNOSISSCAN=
POLYGONSCAN=
OPTIMISTICSCAN=
BASESCAN=

NODE_HOST=http://127.0.0.1:8888
DATA_BUS_ADDRESS=''

PK_KEY=0x

Install the dependencies

yarn

Compile the smart contracts code

yarn compile

Run the tests

yarn test

Test environment

A pre-installed environment can be used to test the smart contract. These environments include

• evm test node
• event monitoring system
• smart contract message spammer

To start the test environment, enter the command:

yarn stand:default

A test environment without message spammer is also provided, enter the command to run it:

yarn stand:monitoring

Deploy

The contract has already been partitioned at the address 0x37De961D6bb5865867aDd416be07189D2Dd960e6 on the networks:

Blockchain	Block Explorer Link
Chaido	View on Chaido Explorer
Gnosis	View on Gnosis Chain Explorer
Base	View on Base Scan
Optimism	View on Optimistic Ethereum Explorer
Polygon	View on PolygonScan

1. Run ./deploy/network.sh
2. (Optional) Run Testing Stand

The testing stand consists of:

• transaction spammer
• console monitoring

with the help of the testing stand you can visualize the principles of Data Bus operation