Finishing the XCMP message demo

message-broker/src/lib.rs

@@ -133,7 +133,7 @@ impl<T: Trait> XCMPMessageSender<T::XCMPMessage> for Module<T> {
 
 		Self::send_upward_message(
 			&T::UpwardMessage::send_message(dest, message.encode()),
-			UpwardMessageOrigin::Signed,
+			UpwardMessageOrigin::Parachain,
 		)
 	}
 }

test/parachain/runtime/Cargo.toml

@@ -37,6 +37,9 @@ cumulus-message-broker = { path = "../../../message-broker", default-features =
 cumulus-upward-message = { path = "../../../upward-message", default-features = false }
 cumulus-primitives = { path = "../../../primitives", default-features = false }
 
+# Polkadot dependencies
+polkadot-parachain = { git = "https://github.com/paritytech/polkadot", branch = "bkchr-cumulus-branch", default-features = false }
+
 [build-dependencies]
 wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.6" }
 
@@ -69,6 +72,7 @@ std = [
 	"cumulus-message-broker/std",
 	"cumulus-upward-message/std",
 	"cumulus-primitives/std",
+	"polkadot-parachain/std",
 ]
 # Will be enabled by the `wasm-builder` when building the runtime for WASM.
 runtime-wasm = [

test/parachain/runtime/src/lib.rs

@@ -125,8 +125,9 @@ pub const DAYS: BlockNumber = HOURS * 24;
 pub const PRIMARY_PROBABILITY: (u64, u64) = (1, 4);
 
 #[derive(codec::Encode, codec::Decode)]
-pub enum XCMPMessage {
-
+pub enum XCMPMessage<XAccountId, XBalance> {
+	/// Transfer tokens to the given account from the Parachain account.
+	TransferToken(XAccountId, XBalance),
 }
 
 /// The version infromation used to identify this runtime when compiled natively.
@@ -247,15 +248,16 @@ impl cumulus_message_broker::Trait for Runtime {
 	type DownwardMessageHandlers = TokenDealer;
 	type UpwardMessage = cumulus_upward_message::WestendUpwardMessage;
 	type ParachainId = ParachainId;
-	type XCMPMessage = XCMPMessage;
-	type XCMPMessageHandlers = ();
+	type XCMPMessage = XCMPMessage<AccountId, Balance>;
+	type XCMPMessageHandlers = TokenDealer;
 }
 
 impl message_example::Trait for Runtime {
 	type Event = Event;
 	type UpwardMessageSender = MessageBroker;
 	type UpwardMessage = cumulus_upward_message::WestendUpwardMessage;
 	type Currency = Balances;
+	type XCMPMessageSender = MessageBroker;
 }
 
 construct_runtime! {

test/parachain/runtime/src/message_example.rs

@@ -23,12 +23,16 @@ use frame_support::{
 };
 use frame_system::ensure_signed;
 
+use crate::XCMPMessage;
 use codec::{Decode, Encode};
 use cumulus_primitives::{
-	relay_chain::DownwardMessage, DownwardMessageHandler, ParaId, UpwardMessageOrigin,
-	UpwardMessageSender,
+	relay_chain::DownwardMessage,
+	xcmp::{XCMPMessageHandler, XCMPMessageSender},
+	DownwardMessageHandler, ParaId, UpwardMessageOrigin, UpwardMessageSender,
 };
 use cumulus_upward_message::BalancesMessage;
+use polkadot_parachain::primitives::AccountIdConversion;
+use sp_runtime::DispatchResult;
 
 type BalanceOf<T> =
 	<<T as Trait>::Currency as Currency<<T as frame_system::Trait>::AccountId>>::Balance;
@@ -46,6 +50,9 @@ pub trait Trait: frame_system::Trait {
 
 	/// Currency of the runtime.
 	type Currency: Currency<Self::AccountId>;
+
+	/// The sender of XCMP messages.
+	type XCMPMessageSender: XCMPMessageSender<XCMPMessage<Self::AccountId, BalanceOf<Self>>>;
 }
 
 // This pallet's storage items.
@@ -70,6 +77,8 @@ decl_event! {
 		TransferredTokensToRelayChain(AccountId, Balance),
 		/// Transferred tokens to the account on request from the relay chain.
 		TransferredTokensFromRelayChain(AccountId, Balance),
+		/// Transferred tokens to the account from the given parachain account.
+		TransferredTokensViaXCMP(ParaId, AccountId, Balance, DispatchResult),
 	}
 }
 
@@ -78,8 +87,7 @@ decl_module! {
 		/// Transfer `amount` of tokens on the relay chain from the Parachain account to
 		/// the given `dest` account.
 		#[weight = 10]
-		fn transfer_tokens(origin, dest: T::AccountId, amount: BalanceOf<T>) {
-			//TODO: Remove the tokens from the given account
+		fn transfer_tokens_to_relay_chain(origin, dest: T::AccountId, amount: BalanceOf<T>) {
 			let who = ensure_signed(origin)?;
 
 			let _ = T::Currency::withdraw(
@@ -96,6 +104,30 @@ decl_module! {
 			Self::deposit_event(Event::<T>::TransferredTokensToRelayChain(dest, amount));
 		}
 
+		/// Transfer `amount` of tokens to another parachain.
+		#[weight = 10]
+		fn transfer_tokens_to_parachain_chain(
+			origin,
+			para_id: u32,
+			dest: T::AccountId,
+			amount: BalanceOf<T>,
+		) {
+			//TODO we don't make sure that the parachain has some tokens on the other parachain.
+			let who = ensure_signed(origin)?;
+
+			let _ = T::Currency::withdraw(
+				&who,
+				amount,
+				WithdrawReason::Transfer.into(),
+				ExistenceRequirement::AllowDeath,
+			)?;
+
+			T::XCMPMessageSender::send_xcmp_message(
+				para_id.into(),
+				&XCMPMessage::TransferToken(dest, amount),
+			).expect("Should not fail; qed");
+		}
+
 		fn deposit_event() = default;
 	}
 }
@@ -121,3 +153,27 @@ impl<T: Trait> DownwardMessageHandler for Module<T> {
 		}
 	}
 }
+
+impl<T: Trait> XCMPMessageHandler<XCMPMessage<T::AccountId, BalanceOf<T>>> for Module<T> {
+	fn handle_xcmp_message(src: ParaId, msg: &XCMPMessage<T::AccountId, BalanceOf<T>>) {
+		match msg {
+			XCMPMessage::TransferToken(dest, amount) => {
+				let para_account = src.clone().into_account();
+
+				let res = T::Currency::transfer(
+					&para_account,
+					dest,
+					amount.clone(),
+					ExistenceRequirement::AllowDeath,
+				);
+
+				Self::deposit_event(Event::<T>::TransferredTokensViaXCMP(
+					src,
+					dest.clone(),
+					amount.clone(),
+					res,
+				));
+			}
+		}
+	}
+}