Bridge
The Calimero bridge handles the transfer of various assets, including fungible (FTs) and non-fungible tokens (NFTs), between NEAR public network (Testnet or Mainnet) and Calimero private shard. It also facilitates cross-shard contract calls, enabling users to invoke smart contracts from a public contract into the shard.
The Calimero bridge comprises three essential bridge connectors:
- FT connector
- NFT connector
- Cross-shard call connector
FT connector
The FT connector serves as a contract pair that simplifies the transfer of fungible tokens (FTs) between the public chain and the Calimero shard. It provides a straightforward process for locking an FT token on one chain, minting a wrapped version on another chain, and later burning the wrapped token to unlock the original token. To install the FT connector:
- Select FT Connector
- Click on the Install FT Bridge button
Once the installation is successful, you will gain access to the FT page, which presents information about your FT contracts and displays transactions related to fungible tokens.
Register FT token
The Register FT token button is used to pay the storage fee for the FT connector contract on the source side (e.g. Near mainnet side) for the FT token. This allows you to lock your FT using the connector. By registering the connector on the FT, the FT token can keep track of which connector owns the FT. To register an FT token:
- On the FT Connector page, click on the Register FT button
- A popup window will appear, requesting the contract address of your FT token. The contract address is on the source side (e.g. Near mainnet side)
- Enter the contract address of your FT token in the provided field
The registration step is a one-time action. However, some FT tokens such as USDN do not require this step.
NFT connector
The NFT connector serves as a contract pair that facilitates the transfer of non-fungible tokens (NFTs) between the public chain and the Calimero shard. It simplifies the process of locking an NFT on one chain, minting a wrapped version of the token on another chain, and subsequently burning the wrapped token to unlock the original NFT. To install the NFT connector:
- Select NFT Connector
- Click on the Install NFT Bridge button
Once the installation is successful, you will gain access to the NFT page, which presents information about your NFT contracts and displays transactions related to non-fungible tokens.
Cross-shard call
The cross-shard connector is a contract pair used to call one chain's contract methods from another chain. Follow these steps to install the cross-shard call connector:
- Select Cross Shard Call
- Click on the Install XSC button
Once you have successfully installed the cross-shard connector, you will have access to the XSC page. On this page, you can view your XSC contracts and transactions related to cross-shard tokens.
For more details on Bridges and their architecture, refer to the Bridge Architecture documentation.
Permissions Management
To ensure secure access and usage of the Calimero bridge for token transfers and cross-shard calls, it is important to manage permissions effectively. Permissions are used to control which accounts can utilize the bridge's features and perform specific actions.
FT and NFT connector regex rules
The FT and NFT connectors allow you to define regex rules that determine which accounts are allowed to bridge tokens. This rule known as the allow regex rule, grant permission to specific accounts, enabling them to utilize the bridge for token transfers.
To add an allow regex rule:
- Click on the Add new rule button
- In the input field, enter a regex pattern that matches the desired accounts for bridging
For example, if you want to allow testnet accounts, you can use the regex pattern .*\.testnet. This regex rule allows any account ending with ".testnet" to bridge tokens using the FT or NFT connector.
Verify FT and NFT connector permissions
To verify whether an account has the necessary permissions to use the FT or NFT connector:
- Click on the Check Permissions button
- Provide the Account ID for which you want to verify the permissions
Cross-shard connector regex rules
Cross-shard connectors have two rules: the account allow rule (similar to FT and NFT connectors) and the deny account rule.
Cross-shard allow regex rule
The cross-shard allow regex rule grants permission to specific accounts, enabling them to utilize the bridge for token transfers.
To add an allow regex rule:
- Click on the Add new rule button
- In the input field, enter a regex pattern that matches the desired accounts for bridging.
For example, if you want to allow testnet accounts, you can use the regex pattern .*\.testnet.
This regex rule allows any account ending with ".testnet" to bridge tokens using the cross-shard connector.
Cross-shard deny regex rule
The deny account rule explicitly denies access or permission to a specific account or set of accounts to a specific contract or set of contracts.
To add a deny account rule regex rule:
Click on the Add new rule button
Enter a regex pattern in the input fields to specify which account and contract pairs should be denied permission for cross-shard calls.
For example, using the regex pattern .*evil.* for the Account ID and .* for the Contract ID will block any accounts containing the term "evil" from making cross-shard calls.
Verify cross-shard connector permission
To verify if a specific pair of Account ID and Contract ID is eligible for making cross-shard calls:
- Click on the Check Permissions button
- In the input fields, enter the relevant Account ID and Contract ID that you want to check for permissions
This process will determine if the specified pair has the necessary permissions to perform cross-shard calls.
For more detailed information regarding permissions, refer to the Permissions documentation.