Things to be explained in the course:

1. What is Ledger? More details here: https://internetcomputer.org/docs/current/developer-docs/integrations/ledger/
2. What is Internet Identity? More details here: https://internetcomputer.org/internet-identity
3. What is Principal, Identity, Address? https://internetcomputer.org/internet-identity | https://yumimarketplace.medium.com/whats-the-difference-between-principal-id-and-account-id-3c908afdc1f9
4. Canister-to-canister communication and how multi-canister development is done? https://medium.com/icp-league/explore-backend-multi-canister-development-on-ic-680064b06320

Getting started

To get started developing in the browser, click this button:

If you rather want to use GitHub Codespaces, click this button instead:

NOTE: After deploying your canisters in GitHub Codespaces, run ./canister_urls.py and click the links that are shown there.

If you prefer running VS Code locally and not in the browser, click "Codespaces: ..." or "Gitpod" in the bottom left corner and select "Open in VS Code" in the menu that appears. If prompted, proceed by installing the recommended plugins for VS Code.

To develop fully locally, first install Docker and VS Code and start them on your machine. Next, click the following button to open the dev container locally:

How to deploy canisters implemented in the course

Ledger canister

./deploy-local-ledger.sh - deploys a local Ledger canister. IC works differently when run locally so there is no default network token available and you have to deploy it yourself. Remember that it's not a token like ERC-20 in Ethereum, it's a native token for ICP, just deployed separately. This canister is described in the dfx.json:

	"ledger_canister": {
  	"type": "custom",
  	"candid": "https://raw.githubusercontent.com/dfinity/ic/928caf66c35627efe407006230beee60ad38f090/rs/rosetta-api/icp_ledger/ledger.did",
  	"wasm": "https://download.dfinity.systems/ic/928caf66c35627efe407006230beee60ad38f090/canisters/ledger-canister.wasm.gz",
  	"remote": {
    	"id": {
      	"ic": "ryjl3-tyaaa-aaaaa-aaaba-cai"
    	}
  	}
	}

remote.id.ic - that is the principal of the Ledger canister and it will be available by this principal when you work with the ledger.

Also, in the scope of this script, a minter identity is created which can be used for minting tokens for the testing purposes. Additionally, the default identity is pre-populated with 1000_000_000_000 e8s which is equal to 10_000 * 108 ICP. The decimals value for ICP is 108.

List identities: dfx identity list

Switch to the minter identity: dfx identity use minter

Transfer ICP: dfx ledger transfer <ADDRESS> --memo 0 --icp 100 --fee 0 where:

• --memo is some correlation id that can be set to identify some particular transactions (we use that in the marketplace canister).
• --icp is the transfer amount
• --fee is the transaction fee. In this case it's 0 because we make this transfer as the minter idenity thus this transaction is of type MINT, not TRANSFER.
• <ADDRESS> is the address of the recipient. To get the address from the principal, you can use the helper function from the marketplace canister - getAddressFromPrincipal(principal: Principal), it can be called via the Candid UI.

ICRC2 ledger canister

deploy-local-icrc-ledger.sh - deploys an ICRC2 canister.

Transfer ICRC token: dfx canister call icrc1_ledger_canister icrc1_transfer '(record { to = record { owner = principal "<PRINCIPAL>";}; amount = <AMOUNT>;})' where:

• <PRINCIPAL> is the principal string of the receiver
• <AMOUNT> is the amount of token to be transferred

Internet identity canister

deploy-local-identity.sh - deploys an identity canister and outputs the canister id to .env as the IDENTITY_CANISTER_ID variable. Once it's deployed, the js-agent library will be talking to it to register identities. There is UI that acts as a wallet where you can select existing identities or create a new one.

Marketplace canister

Switch to the default identity: dfx identity use default

deploy-local-backend-canister.sh - deploys the marketplace canister where the business logic is implemented and outputs the canister id to .env as the BACKEND_CANISTER_ID variable. Basically, it implements functions like add, view, update, delete, and buy products + a set of helper functions.

Marketplace frontend canister

dfx deploy dfinity_js_frontend - deployes the frontend app for the dfinity_js_backend canister on IC.