TL:DR
This batched proposal is to Accept/Open an HRMP channel with Manta and Register Asset(s) xcMANTA (optional)
Summary
We propose to open a bi-directional channel between Moonbeam and Manta. Initially, the main use case will be to transfer GLMR (optional) and MANTA tokens between the two chains, but it can be further expanded to other use cases. The proposal also includes the MANTA asset registration as xcMANTA, with the following details:
- Multilocation: { parents: 1, interior: { X1: {Parachain: 2104}}}
- Decimals: 18
- Name: Manta
- Symbol: xcMANTA
xcMANTA will have the following asset ID and XC-20 address:
- Asset ID: 166446646689194205559791995948102903873
- XC-20 address: 0xffffffff7d3875460d4509eb8d0362c611b4e841
Note: xcMANTA transfers will be disabled temporarily until the MANTA token is officially listed.
[Note: you can calculate the asset ID and XC-20 address using this script. For example: yarn calculate-external-asset-info --a ‘[MULTILOCATION OF ASSET]’
On-Chain Proposal Reference
On-Chain Referendum #[97] with the associated hash: 0xd0820aa59c1a693527bd0d4835f8ddff133ed4ba350719f50ff100e1343ae137
[Note: you can get the Proposal Number and Associated Hash from Polkadot.js Apps in Moonbeam]
Technical details:
The procedure for opening the channels is as follows:
- Manta: already proposed to open an HRMP channel to Moonbeam
- Moonbeam: democracy batched proposal:
- Accept HRMP channel from Manta to Moonbeam
- Open Moonbeam to Manta HRMP channel
- Register MANTA asset as an XC-20 (optional)
- Manta: democracy proposal to accept Moonbeam to Manta HRMP channel
Once the HRMP channels are ready, XCM based cross-chain transfer will be possible. The extrinsics that need to be executed on the relay chain, are:
- To accept the HRMP channel to Moonbeam: hrmp.hrmpAcceptOpenChannel(sender: [parachainId]) , which hex-encoded call data is 0x3c0138080000
- To open the HRMP channel from Moonbeam: hrmp.hrmpInitOpenChannel(recipient: [parachainId], proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400), which its hex-encoded call data is 0x3c0038080000e803000000900100
[Note: you can get the hex encoded call data for both calls in the relay chain extrinsic page for both Polkadot. You’ll need to build the call there.]
The *proposedMaxCapacity *and proposedMaxMessageSize are set to the values of Polkadot/Kusama configuration.activeConfig.hrmpChannelMaxCapacity and configuration.activeConfig.hrmpChannelMaxMessageSize values, respectively.
These extrinsics need to be called from the parachain’s sovereign account as origin, via a democracy proposal. The proposal will use polkadotXcm pallet to send XCM message to the Relay Chain with the following items:
- Withdraw asset: take funds out of the Sovereign Account of the origin parachain (in the relay chain) to a holding state
- Buy execution: buys execution time from the relay chain, to execute the XCM message
- Transact: provides the call data to be executed
- Deposit asset (optional): refunds the leftover funds after the execution. If this is not provided, no refunds will be carried out
The asset will be registered with the metadata described in the summary. The setAssetUnitsPerSecond was calculated using the value for MANTA during its presale, targeting a XCM transaction cost of 0.02$.
If you are interested, the hex-encoded call data for this proposal in Moonbeam are respectively:
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
As a prerequisite, the parachain’s sovereign account must contain at least 20 DOT/KSM to be locked as collateral (10 for each channel direction), plus some DOT/KSM to pay for XCM execution fees.