Student transfer between parachains

Cross-Parachain Communication Demo (Polkadot Local Network)

University Parachain (1000) → Company Parachain (2000)
Technologies and frameworks used: XCM, HRMP, Zombienet, and Polkadot SDK

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🎯 Project Focus

This repository demonstrates XCM (Cross-Consensus Messaging) between two sibling parachains running on a local Polkadot network.

• Students are created on Parachain 1000 (University)
• Graduating a student triggers an XCM Transact
• Student data is executed and stored on Parachain 2000 (Company)
• State changes are visualized via a React + Vite frontend

The goal of the project is to showcase real, executable cross-parachain calls, not UI complexity or node setup.

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🧩 Architecture

Relay Chain (9944)
│
├─ Parachain 1000 (University) ──▶ HRMP ──▶ Parachain 2000 (Company)
│        9988                                  9999
│
└─ React + Vite Frontend (5173)

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🌐 Ports & Access

Component	Address / Port
Relay Chain	ws://127.0.0.1:9944
Parachain 1000	ws://127.0.0.1:9988
Parachain 2000	ws://127.0.0.1:9999
Frontend UI	http://localhost:5173

⚠️ Port 5173 must be open to access the UI.

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🧪 Local Network (Zombienet)

The network is started using Zombienet:

zombienet --provider native spawn zombienet.toml

📖 Zombienet documentation:
https://paritytech.github.io/zombienet/

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🔁 HRMP Channel (Required for XCM)

An HRMP channel (1000 → 2000) must be opened on the relay chain.

Run the script while Zombienet is starting (after a few seconds):

./setup-channels.sh

This script uses sudo on the relay chain (Alice) to open the channel via hrmp.forceOpenHrmpChannel.

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🖥️ Frontend

The frontend is built with:

• React 18
• Vite
• Tailwind CSS
• polkadot.js API
• lucide-react icons

Run frontend

cd frontend
npm install
npm run dev

UI available at:
👉 http://localhost:5173

The UI connects directly to:

• Parachain 1000 (9988)
• Parachain 2000 (9999)

and signs transactions using the Alice dev account.

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🔍 Inspecting On‑Chain State

For detailed on-chain inspection, use Polkadot.js Apps:

• Relay Chain:
  https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:9944

• University Parachain (1000):
  https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:9988

• Company Parachain (2000):
  https://polkadot.js.org/apps/?rpc=ws://127.0.0.1:9999

Useful sections:

• Developer → Extrinsics
• Developer → Chain state
• Network → Explorer
• XCM / HRMP events on relay chain

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✉️ XCM Flow (High Level)

1. User clicks Graduate Student in UI
2. graduateStudent extrinsic executes on Para 1000
3. Student data is encoded into an XCM Transact
4. XCM message routed via Relay Chain
5. Para 2000 executes receiveStudent
6. Student appears on Company parachain

Security is enforced via:

• XCM Barriers
• SafeCallFilter
• Sibling parachain origin checks

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🔧 Development Notes

Rebuilding Runtime / Pallets / Node

Whenever binary code changes (runtime, pallets, node):

cargo build --release
cargo install --path node

Zombienet must be restarted after rebuilding.

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📁 Project Structure

.
├── node/                    # Parachain node
├── runtime/                 # Runtime + XCM config
├── pallets/                 # Student pallet
├── frontend/                # React + Vite UI
├── zombienet.toml
├── zombienet-omni-node.toml
├── setup-channels.sh        # HRMP setup script
├── dev_chain_spec.json
├── Cargo.toml
├── Cargo.lock
└── README.md

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🧬 Origin

This project is based on the official:

polkadot-sdk-parachain-template
https://github.com/paritytech/polkadot-sdk-parachain-template

and extended with:

• Custom student pallet
• XCM configuration
• HRMP messaging
• Frontend visualization

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📜 License

Unlicensed / Public Domain.

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