## TL:DR

This batched proposal is to Accept/Open an HRMP channel with Acala and to register the ACA & aUSD token

## Summary

We propose to open a bi-directional channel between Moonbeam and Acala. Initially, the main use case will be to transfer GLMR and ACA-aUSD between the two chains, but it can be further expanded to other use cases. The proposal also includes the ACA & aUSD asset registration as xcACA and xcaUSD, with the following details:

ACA:
 - Multilocation: *{ "parents": 1, "interior": {"X2": { "Parachain": 2000}, {"GeneralKey": 0x0000}}*
 - Decimals: *12*
 - Name: *Acala*
 - Symbol: *xcACA*

aUSD:
 - Multilocation: *{ "parents": 1, "interior": {"X2": { "Parachain": 2000}, {"GeneralKey": 0x0001}}*
 - Decimals: *12*
 - Name: *Acala Dollar*
 - Symbol: *xcaUSD*

xcACA will have the following asset ID and XC-20 address:
 - Asset ID: 224821240862170613278369189818311486111
 - XC-20 address: 0xffffffffa922fef94566104a6e5a35a4fcddaa9f

xcaUSD will have the following asset ID and XC-20 address:
 - Asset ID: 110021739665376159354538090254163045594
 - XC-20 address: 0xffffffff52c56a9257bb97f4b2b6f7b2d624ecda

## Proposal

Proposal #38 with the following hash: *0x5fbba251db28e2777fd1ad0a6edaaec1cc35e5c893c36f6bc61230c59f25f81b*

## Technical details:

The procedure for opening the channels is as follows:

- Acala: already proposed to open an HRMP channel to Moonbeam
- Moonbeam: democracy batched proposal
    - Open Moonbeam to Acala HRMP channel
    - Accept Acala to Moonbeam HRMP channel
    - Register ACA & aUSD asset as an XC-20 
- Acala: democracy proposal to accept Moonbeam to Acala 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 Moonbeam: hrmp.hrmpInitOpenChannel(recipient: *2000*, proposedMaxCapacity: 1000, proposedMaxMessageSize: 102400), which its hex-encoded call data is *0x3c00d0070000e803000000900100*

To accept this HRMP channel: hrmp.hrmpAcceptOpenChannel(sender: 2000) , which hex-encoded call data is *0x3c01d0070000*

The *proposedMaxCapacity* and *proposedMaxMessageSize* are set to the values of Polkadot’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 an estimated value for ACA and aUSD value on May 3rd 2022, targeting a XCM transaction cost of 0.02$.

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

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

As a prerequisite, the parachain’s sovereign account must contain at least 20 DOT to be locked as collateral (10 for each channel direction), plus some DOT 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 Moonbeam and Acala.
- They want to transfer GLMR and ACA-aUSD between the two chains.
- They also want to register ACA and aUSD as xcACA and xcaUSD tokens.
- The proposal number is #38.
- They need to execute some technical steps to make the channels work.

#38 Open/Accept HRMP channel to/from Acala and Register ACA, aUSD Assets

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