Flight Plan

• Play with a Web App
• Is that Blockchain!?
• Decentralize our App
• Add a Module
• Forks and Upgrades
• Remove a Module
• Write a custom module

Play with a Web App

• Try the hosted frontend
• Template for rapid UI development
• Github repository

Apps: A Multimeter for Substrate

• Hosted at https://polkadot.js.org/apps/
• Github repository

Bonus: Browser Extension

• Github repository
• Download from addons.mozilla.org
• Download from chrome web store

Decentralize our App

• Why Decentralize
  • Immutability
  • Censorship Resistance
  • Verifiable
  • Resiliant
• Compile the substrate-node-template
• Roughly following this tutorial

Compilation Steps

• Install system dependencies
  • sudo apt install cmake pkg-config libssl-dev git clang libclang-dev
  • brew install cmake pkg-config openssl git llvm
• curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
• git clone https://github.com/substrate-developer-hub/substrate-node-template
• cd substrate
• scripts/init.sh
• cargo build --release

Blockchain is like Git

In the meantime, let's talk about how blockchain works.

Problem: Social coordination

Solution:

• Social Contract
• Shared History

Generate Two Keys

• sr25519 for Babe block production
• ed25519 for Grandpa finalization

Share your addresses, and REMEMBER YOUR PHRASES!

Join the Network

Download the chainspec file.

./target/release/node-template \
  --chain=customSpecRaw.json \
  --validator \
  --name YOURNAME \
  --telemetry-url ws://telemetry.polkadot.io:1024

Apps > Toolbox > RPC Calls > author > insertKey

Add Tic Tac Toe Module

• Update Code
  • Cargo.toml -- dependency, std feature
  • lib.rs -- impl trait, costruct_runtime, bump spec version
• Recompile     cargo build --release
• View the solution

Perform a Runtime Upgrade

• Hosted interface
• Interface repository
• Runtime module repository
• Necessary type declarations

Remove Sudo Module

• Update Code
  • Cargo.toml -- dependency, std feature
  • lib.rs -- impl trait, costruct_runtime, bump spec version
  • chain_spec.rs -- config and import
• Recompile     cargo build --release
• View the solution

Upgrade same as before

No special interface this time

Custom Proof of Existence Module

Proof of Existence == Timestamped Notary Service

Certify any file Trustlessly

Roughly following this tutorial

Lots more to learn at substrate.dev