Payments

Leases are paid from deployment owner (tenant) to the provider through a deposit & withdraw mechanism.

Bid Deposits

Tenants are required to submit a deposit when creating a deployment. Leases will be paid passively from the balance of this deposit. At any time, a lease provider may withdraw the balance owed to them from this deposit.

If the available funds in the deposit ever reaches zero, a provider may close the lease. A tenant can add funds to their deposit at any time. When a deployment is closed, the unspent portion of the balance will be returned to the tenant.

Bidding on an order requires a deposit to be made. The deposit will be returned to the provider account when the bid transitions to state CLOSED.

Bid deposits are implemented with an escrow account module. See here for more information.

Escrow Accounts

Escrow accounts are a mechanism that allow for time-based payments from one account to another without block-by-block micropayments. They also support holding funds for an account until an arbitrary event occurs.

Escrow accounts are necessary in nexqloud for two primary reasons:

1. Leases in Nexqloud are priced in blocks - every new block, a payment

   from the tenant (deployment owner) to the provider (lease holder)

   is due. Performance and security considerations prohibit the

   naive approach of transferring tokens on every block.

2. Bidding on an order should not be free (for various reasons, including performance and security). Nexqloud requires a deposit for every bid. The deposit is returned to the bidder when the bid is closed.

Escrow accounts are created with an arbitrary ID, an owner, and a balance. The balance is immediately transferred from the owner account to the escrow module account. Accounts may have their balance increased by being deposited to after creation.

Payments represent transfers from the escrow account to another account. They are (currently) block-based - some amount is meant to be transferred for every block. The amount owed to the payment from the escrow account is subtracted from the escrow account balance through a settlement process.

Payments may be withdrawn from, which transfers any undisbursed balance from the module account to the payment owner's account.

When an account or a payment is closed, any remaining balance will be transferred to their respective owner accounts.

If at any time the amount owed to payments is greater than the remaining balance of the account, the account and all payments are closed with state OVERDRAWN.

Many actions invoke the settlement process and may cause the account to become overdrawn.

How are gas fees calculated on Nexqloud?

Nexqloud uses the basic Cosmos gas calculations for all fees. Cosmos documentation on gas can be found here.

Account Settlement

Account settlement is the process of updating internal accounting of the balances of payments for an account to the current height.

Many actions trigger the account settlement process - it ensures an up-to-date ledger when acting on the account.

Account settlement goes as follows:

1. Determine blockRate - the amount owed for every block.

2. Determine heightDelta - the number of blocks since last settlement.

3. Determine numFullBlocks - the number of blocks that can be paid for in full.

4. Transfer amount for numFullBlocks to payments.

5. If numFullBlocks is less than heightDelta (account overdrawn), then

   1. Distribute remaining balance among payments, weighted by each payment's rate

   2. Distribute any remaining balance from above as evenly as possible

   3. Set account and payments to state OVERDRAWN.

Models

Account

Field	Description
ID	Unique ID of account.
Owner	Account address of owner.
State	Account state.
Balance	Amount deposited from owner account.
Transferred	Amount disbursed from account via payments.
SettledAt	Last block that payments were settled.

Account State

Name
OPEN
CLOSED
OVERDRAWN

Payment

Field	Description
AccountID	Escrow Account ID.
PaymentID	Unique (over AccountID) ID of payment.
Owner	Account address of owner.
State	Payment state.
Rate	Tokens per block to transfer.
Balance	Balance currently reserved for owner.
Withdrawn	Amount already withdrawn by owner.

Payment State

Name
OPEN
CLOSED
OVERDRAWN

Methods

AccountCreate

Create an escrow account. Funds are deposited from the owner account to the escrow module account.

Arguments

Field	Description
ID	Unique ID of account.
Owner	Account address of owner.
Deposit	Amount deposited from owner account.

AccountDeposit

Add funds to an escrow account. Funds are transferred from the owner account to the escrow module account.

Arguments

Field	Description
ID	Unique ID of account.
Amount	Amount deposited from owner account.

AccountSettle

Re-calculate remaining account and payment balances.

Arguments

Field	Description
ID	Unique ID of account.

AccountClose

Close account - settle and close payments, return remaining account balance to owner account.

Arguments

Field	Description
ID	Unique ID of account.

PaymentCreate

Create a new payment. The account will first be settled; this method will fail if the account cannot be settled.

Arguments

Field	Description
AccountID	Escrow Account ID.
PaymentID	Unique (over AccountID) ID of payment.
Owner	Account address of owner.
Rate	Tokens per block to transfer.

Invariants

• Account is in state OPEN after being settled.

• ID is unique.

• Owner exists.

• Rate is non-zero and account has funds for one block.

PaymentWithdraw

Withdraw funds from a payment balance. Account will first be settled.

Arguments

Field	Description
AccountID	Escrow Account ID.
PaymentID	Unique (over AccountID) ID of payment.

PaymentClose

Close a payment. Account will first be settled.

Arguments

Field	Description
AccountID	Escrow Account ID.
PaymentID	Unique (over AccountID) ID of payment.

Hooks

Hooks are callbacks that are registered by users of the escrow module that are to be called on specific events.

OnAccountClosed

Whenever an account is closed OnAccountClosed(Account) will be called.

OnPaymentClosed

Whenever a payment is closed, OnAccountClosed(Account) will be called.