Extending the Metadata of an Asset

Any web3 account use the AssetMetadataExtender interface to extend the metadata of any asset, in any chain, and evolve their extensions over time.

The interface can be found in both Solidity and ABI json format here. The interface is available at the contract address 0x0000000000000000000000000000000000000405.

The main entry point is the extendTokenURI method:

// Interace available at contract address 0x0000000000000000000000000000000000000405
function extendULWithExternalURI(
    string calldata _uloc,
    string calldata _tokenURI
) external;

The input parameters are:

  • _uloc: the Universal Location identifying the asset in its corresponding chain,

  • _tokenURI: the location where the metadata of the extension can be fetched; ideally, it should point to a permissionless decentralized system, such as IPFS, or its incentivized versions, such as Filecoin or Crust.

On success, this transaction emits a corresponding event:

event ExtendedULWithExternalURI(
    address indexed _claimer,
    bytes32 indexed _universalLocationHash,
    string _universalLocation,
    string _tokenURI

Besides emitting the web3 account that created the extension (as _claimer), this method also includes the hash of the Universal Location that was extended (as _universalLocationHash). The latter parameter is indexed, which can be useful for DApps that query about events related to a particular asset.

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