HRMP (Horizontally Relay-routed Message Passing) is a stop-gap that predates XCMP. Semantically, it mimics XCMP’s interface. The crucial difference from XCMP though is that all the messages are stored in the relay-chain storage. The HRMP will be expected to retire once the XCMP is available.
Opening of HRMP channel between Bifrost and Karura will initially realize the cross-chain communication between two parachains:
- Tokens on both sides can be transferred to each other.
- Messages can be received on both sides, calling functions by each other.
- Voting Period: #488,880
- Activate Period: #489,180
- Encoded call:
- Proposal preimage:
- Proposal hash:
This withdraw 1 KSM to buy transaction fee, execute the call to accept open channel request, and refund remaining KSM to the parachain sovereign account
Two proposals are required on Karura and Bifrost to establish a bidirectional HRMP channel.
The whole flow will be roughly like this:
- Initiate requests
a. Karura propose to request to open Karura to Bifrost HRMP channel
b. Bifrost propose to request to open Bifrost to Karura HRMP channel
- Wait until proposals on step 1 are approved & enacted
- Accept requests
a. Karura propose to accept Bifrost to Karura HRMP channel
b. Bifrost propose to accept Karura to Bifrost HRMP channel
- Wait until proposals on step 3 are approved & enacted
- Wait for another session on Kusama for the change to be effective
- Cross-chain transfer BNC will be possible at this stage. Other kinds of cross-chain interaction such as transfer of KAR & kUSD will be enabled at a later stage via runtime upgrade of Karura & Bifrost.
As mentioned above and #6 referendum proposal, the current HRMP opening process has reached stage
3.b, this proposal will accept a request from Karura to open the HRMP channel. After the channel is opened, this will be the first time in history that two parachains have communicated with XCM in the production environment, let us witness history together!