Simple-XCMP-Parachain

This is a project for learning exploring blockchain runtime development with Substrate, Cumulus Parachain and the FRAME.

This project implements a simple XCMP protocol between two parachains where one parachain makes pallet call of another parachain.

pallet-counter Design

This pallet defines a simple logic to set , increment and make xcm calls. Same pallet is used on both the parachain for testing xcmp functionality.

Requirements

• Follow Below steps to set up Relay Node and Parachain Node
• Only sudo user can make pallet call
• Build HRMP channel between( Parachain(2000) , Parachain(2001))

Pallet Calls

• set_counter(origin, para, value)

set_counter method takes paraid and value as input and makes set_counter_value() pallet call of Parachain(paraID) by sending xcm message.

• increment_counter(origin,para)

increment_counter method takes paraId and makes increment_counter_value() pallet call of Parachain(ParaId) by sending xcm message.

Storages

• Counter: StorageValue => u32

Events

• CounterSet(ParaId, u32)
• CounterIncremented(ParaId)

Errors

• ErrorSettingCounter
• ErrorIncrementingCounter

Step1 Building the relay Chain node.

# Clone the Polkadot Repository
$ git clone https://github.com/paritytech/polkadot.git

# Switch into the Polkadot directory
$ cd polkadot

# Checkout the proper commit
git checkout v0.9.16

# Build the relay chain Node
$ cargo build --release

# Check if the help page prints to ensure the node is built correctly
$ ./target/release/polkadot --help

1.2 Generate relay chain spec file.

There must be minimum 2 validator for 1 parachain. In this project we will be using two parachains , so therefore we will require 3 validator nodes Check here to learn more here.

./target/release/polkadot build-spec \
--chain rococo-local \
--raw \
--disable-default-bootnode \
> rococo_local.json

You can use pre configured chain spec file for testing from here

1.3 Start relay node with 3 validator Alice, Bob and Charlie

• Alice

./target/release/polkadot \
--alice \
--validator \
--base-path /tmp/relay/alice \
--chain ./rococo-custom-3-raw.json \
--port 30333 \
--ws-port 9944

• Bob

./target/release/polkadot \
--bob \
--validator \
--base-path /tmp/relay-bob \
--chain ./rococo-custom-3-raw.json \
--bootnodes /ip4/127.0.0.1/tcp/30333/p2p/<ALICE NODE IDENTIFIER> \
--port 30334 \
--ws-port 9945

• Charlie

./target/release/polkadot \
--charlie \
--validator \
--base-path /tmp/relay-charlie \
--chain /Users/salman01z/Crypto/parachains/chain_spec_files/rococo-custom-3-raw.json \
--bootnodes /ip4/127.0.0.1/tcp/30333/p2p/<ALICE NODE IDENTIFIER>\
--port 30335 \
--ws-port 9946

Step2 Build Parachain

2.1 Reserve Parachain ID

Resure Parachain ID using [Polkadot-js](https://polkadot.js.org/apps/?rpc=ws%3A%2F%2F127.0.0.1%3A9944#/parachains/parathreads)
Parachain ids start with 2000

2.2 Configure Parachain for Relay chain and Para ID

• Generate Plain spec with:

./target/release/parachain-collator build-spec --disable-default-bootnode > rococo-local-parachain-plain.json

• Update Para ID in Plain Spec file

	// --snip--
		"para_id": 2000, // <--- your already registered ID
		// --snip--
			"parachainInfo": {
				"parachainId": 2000 // <--- your already registered ID
	},
	// --snip--

• Generate Raw spec file from Plain Spec file

./target/release/parachain-collator build-spec --chain rococo-local-parachain-plain.json --raw --disable-default-bootnode > rococo-local-parachain-2000-raw.json

• Generate Wasm runtime blob

./target/release/parachain-collator export-genesis-wasm --chain rococo-local-parachain-2000-raw.json > para-2000-wasm

• Generate Parachain Genesis State (hex encoded)

./target/release/parachain-collator export-genesis-state --chain rococo-local-parachain-2000-raw.json > para-2000-genesis

2.3 Start Collator Node

	./target/release/parachain-collator \
	--alice \
	--collator \
	--force-authoring \
	--chain rococo-local-parachain-2000-raw.json \
	--base-path /tmp/parachain1/alice \
	--port 40333 \
	--ws-port 8844 \
	-- \
	--execution wasm \
	--chain ./rococo-custom-3-raw.json \
	--bootnodes /ip4/127.0.0.1/tcp/30333/p2p/<Bootnode Identifier> \
	--port 30343 \
	--ws-port 9977

Second Parachain

Repeat All the above steps with different Para ID, base path and ports. Use same relay chain spec.