## TL:DR

This batched proposal is to Accept/Open an HRMP channel with Crab and to register the CRAB token

## Summary

We propose to open a bi-directional channel between Moonriver and Crab Network. Initially, the main use case will be to transfer MOVR and CRAB between the two chains, but it can be further expanded to other use cases. The proposal also includes the CRAB asset registration as xcCRAB, with the following details:

 - Multilocation: *{ "parents": 1, "interior": {"X2": [{ "Parachain": 2105 },{"PalletInstance": 5 }]}}*
 - Decimals: *18*
 - Name: *CRAB*
 - Symbol: *xcCRAB*

xcCRAB will have the following asset ID and XC-20 address:
 - Asset ID: 173481220575862801646329923366065693029
 - XC-20 address:  0xffffffff8283448b3cb519ca4732f2dddc6a6165

## Proposal

Proposal #21 with the following hash: *0x7fb22a89b5e0e420de88eda30ec05b1e387fa8d442e2d0810e837aa08c67a27c*

## Technical details:

The procedure for opening the channels is as follows:
 - Crab: already proposed to open an HRMP channel to Moonriver
 - Moonriver: democracy batched proposal:
     - Open Moonriver to Crab HRMP channel
     - Accept Crab to Moonriver HRMP channel
    - Register CRAB asset as an XC-20 
 - Crab: democracy proposal to accept Moonriver to Crab 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 open the HRMP channel from Moonriver: *hrmp.hrmpInitOpenChannel(recipient: 2105, proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400)*, which its hex-encoded call data is *0x3c0039080000e803000000900100*
 - To accept the HRMP channel to Moonriver: *hrmp.hrmpAcceptOpenChannel(sender: 2105)* , which hex-encoded call data is *0x3c0139080000*

The *proposedMaxCapacity *and *proposedMaxMessageSize *are set to the values of Kusama’s *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 CRAB value on May 24th 2022, targeting a XCM transaction cost of 0.02$.

If you are interested, the hex-encoded call data for this proposal in [Moonriver](https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Fwss.api.moonriver.moonbeam.network#/extrinsics/decode) is:

0x1e020c670001010002100004000000000700e876481713000000000700e8764817010700f2052a01060002286bee183c01390800000d0100040001010070617261e7070000000000000000000000000000000000000000000000000000670001010002100004000000000700e876481713000000000700e8764817010700f2052a01060002286bee383c0039080000e8030000009001000d0100040001010070617261e70700000000000000000000000000000000000000000000000000001e020c690000010200e520040550437261622050617261636861696e20546f6b656e1878634352414212000100000000000000000000000000000001690100010200e5200405497df38cb33960f51d030000000000001500000000050411011da53b775b270400e7e61ed5cbc5a146ea70f53d5a3306ce02aaf97049cf181a04b9ee56f293441166ad0f2a4968c8ceffffffff8283448b3cb519ca4732f2dddc6a6165181460006000fd

As a prerequisite, the parachain’s sovereign account must contain at least 10 KSM to be locked as collateral (5 for each channel direction), plus some KSM to pay for XCM execution fees.

 

Send a batch of dispatch calls and atomically execute them.
The whole transaction will rollback and fail if any of the calls failed.

May be called from any origin.

- `calls`: The calls to be dispatched from the same origin. The number of call must not
  exceed the constant: `batched_calls_limit` (available in constant metadata).

If origin is root then call are dispatch without checking origin filter. (This includes
bypassing `frame_system::Config::BaseCallFilter`).

# <weight>
- Complexity: O(C) where C is the number of calls to be batched.
# </weight>

- The proposal is to open a channel between Moonriver and Crab networks.
- The channel will allow for the transfer of MOVR and CRAB tokens between the two networks.
- The CRAB token will be registered as xcCRAB with specific details.
- The proposal has a hash number: 0x7fb22a89b5e0e420de88eda30ec05b1e387fa8d442e2d0810e837aa08c67a27c.
- There are technical details and steps involved in opening the channels and executing the necessary transactions.

#94 Open/Accept HRMP channel to/from Crab Network and Register CRAB Asset