Traffic Purchase

Traffic credits are used for all submissions to the Global Synchronizer. Traffic costs are charged for sending all data based on the size of the messages and its delivery cost. However only the sending validator node is charged. Please refer to Synchronizer Traffic Fees for more details.

A validator increases its traffic credit balance by burning CC at the current USD-to-Canton-Coin conversion rate (a USD/MB price). When needed, the operator of a validator (or a third-party service provider) burns CC in exchange for traffic credits. The CC burned creates a ValidatorRewardCoupon with the amount of CC burnt and where the user is the validator operator of the validator hosting the purchasing party. There is no application involved so no AppRewardCoupon is created.

To avoid running out of traffic credits, the ability to perform automatic traffic purchases is provided and recommended. Please see Configuring automatic traffic purchases. Alternatively, Daml application code can use AmuletRules_BuyMemberTraffic to increase the traffic credit balance.

Note that traffic credits are used whenever a confirmation request for a Daml transaction is sent to the Global Synchronizer. The traffic is consumed even if the confirmation request fails due to contention on consuming contracts. For example, when submitting two Transfer operations that consume the same Amulet contracts.

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