The Data Activity Capture (DAC) system is a crucial part of the DDC infrastructure. It monitors activity within the cluster to ensure that content is being exchanged according to the DDC core protocol. To achieve this, activity logs from DDC nodes are continuously collected and aggregated. The collected data is then supplied to important components in the Cere’s DDC infrastructure to ensure fair payouts for node providers, prevent dishonesty, and guarantee fairness for all parties involved.
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DDC users must confirm the receipt of each piece of content they receive by sending a signed receipt to the node that served the content. These receipts are then signed by the nodes and combined into records known as activity reports. These activity reports serve as cryptographic proof of the content exchange. The DAC system consumes the stream of activity reports provided by each DDC node periodically. The system then tabulates and indexes the reports to extract relevant data about the amount and quality of work carried out by each DDC node as well as information on its current status. The data collected by DAC is then checked by blockchain validators at fixed regular intervals known as eras. The validators use this data to either reward DDC nodes for their utility to the cluster or penalize them for violating the protocol or SLA. A quorum of validators (at least 3) is assigned to process the data for the same DDC node. Each validator retrieves aggregations from DAC. Since each validator retrieves aggregations for a subset of DDC nodes, each validator takes part in multiple quorums. The validators then gossip validation results and finally reach a consensus on the set of nodes to reward and the penalties to apply. Once the quorum on the validation decision is achieved and validators agree on the final validation decision, customers are charged for the resources that they used during the era, such as the number of requests, amount of bytes streamed, and/or storage space used. Providers, on the other hand, are rewarded for the amount of work they have done in terms of resources provided since the last validation cycle. If the validation process identifies any misbehavior by a specific DDC node, the node may no longer be eligible for a reward until an operator takes action. In certain cases, a DDC node may even be penalized for an inadmissible protocol violation by deduction of the security deposit down to zero.
