RemoteTreasury pallet

[dutterbutter]

Implementation details

Similar to LocalTreasury with extra functionality to control assets on other chains via XCMP. The RemoteTreasury will be responsible for DOT, which will be controlled through XCMP on the relay chain.

Acceptance Criteria

The completed pallet should have the following functionality:

• execute

[mattsse]

Related: open-web3-stack/open-runtime-module-library#385 and XCM Implementation for Fungible Assets

[mattsse]

From the design document it was not immediately obvious to me which functionality the remote treasury should provide as extrinsic.

The RemoteTreasury will be responsible for DOT, which will be controlled through XCMP on the relay chain.

However, only dispatching calls via execute is listed here.
My understanding is, the remote-treasury will manage the DOTs deposited on the relay chain and, similar to local-treasury, the admin should be able to withdraw, or rather transfer, DOTs from this treasury's account into a recipient account on the relay chain via XCMP.

I attempted to implement this in #34 as transfer_dot extrinsic, where the admin can initiate a transfer of DOT by executing issuing a withdrawal from the treasury account on the relay that is then deposited into the recipient's account on the relay chain, via XCMP.

I'm currently investigating how to properly test this, but need to clarify that this is the actual anticipated functionality of the pallet. @willemolding @ansermino

[ansermino]

When writing the design doc it was unclear how exactly controlling DOT on the relay chain would function. To compensate for this, the generalized functionality of dispatching a call on another parachain seemed sufficient to support the needs of the treasury. Hence the execute method was defined as a way to dispatch a call to a predefined destination.

Now that XCMP is coming together, I think it's worth rethinking this. What you've implemented in #34 seems sensible, although I do have one gripe. If possible, it would be nice not to constrain the pallet to interact only with DOT and only on the relay chain. I think this would simply require these vars to be passed into the config:

PINT/pallets/remote-treasury/src/lib.rs

Lines 145 to 158 in 6c8b1c6

	let asset = MultiAsset::ConcreteFungible {
	id: Junction::Parent.into(),
	amount: amount.into(),
	};
	// the recipient's account on the relay chain
	let dest = (
	Junction::Parent,
	Junction::AccountId32 {
	network: T::RelayChainNetworkId::get(),
	id: T::AccountId32Convert::convert(recipient.clone()),
	},
	)
	.into();

[mattsse]

I also think that it is important to implement this in a more general way.
They way this currently seems to work is by introducing a currency identifier and declare (id => location) pairs for the trusted reserves for example CurrencyId::DOT => Junction::Parent.

The orml-xtokens-pallet seems to provide this already.

[mattsse]

@ansermino I've added support for general transfers in #34.
I have added support for general transfers, depending on the location of the asset and the destination different routines are executed by xcm. I have tried to a concise description of the possible scenarios:

https://github.com/ChainSafe/PINT/pull/34/files#diff-dff9576416b319287b7ee69b44e99ee4f78b9cc4725d8e3889b7cb387759cb3cR138-R164

[dutterbutter]

Closing, no longer required.