HW07 Composer: Patreon

Create a Business Network Archive (BNA) with the appropriate models, transactions, and access constraints that fulfill the requirements below. The BNA must have an initial transaction (setupHomework) that sets up a ledger state, where the fulfillment of each requirement can be demonstrated (assuming that the ledger is empty before the call of the initial transaction). Transactions that would dynamically add participants or assets are not needed, unless noted explicitly under the requirements, except the initializer transaction.

Please test your solution on Composer Playground before submission.

For every Participant and Asset type, the unique identifier must be a non-optional String field with the name id. The value of the field must conform to the following format: <TYPENAME>_<COUNTER>. For example, if we have a Participant type named User, then the id of the first created user must be USER_0, the id of the second user must be USER_1, etc.

Problem statement

Implement a BNA for supporting an artist.

• There should be at least two participant types: Supporter and Artist.
• Each user has a name (non-unique), a bank account, and a phone number (required).
• Only the account owners can access the funds stored in the accounts.
• Account owners can
  • withdraw money.
  • transfer money to another user.
  • add money to the account.
• The artist can only withdraw at max 10% of the money stored in the account at any given time, and can only withdraw once per week.

Additional requirements:

• The initializer transaction should set up at least 2 users (one artist and one supporter), and their bank accounts.
• Every user has exactly one account.
• Transactions that add a user or switch an account aren't needed.
• Negative balances are not possible, transactions that'd create such a state should be rejected.

Example scenario

Alice is an artist, and Bob is a fan of her work. Alice has an account with 10 units. Bob's account has 5 units. Alice adds her salary of 10 units to her account. Later, Bob tries to withdraw 2 units for rent, which fail. Alice transfers him 6 units. Bob sees this and tries to withdraw 2 units again, this time successfully.

Transactions

• addMoney
• withdrawMoney
• transferMoney