Problem
Today we have the last reporting window for event-level reports coupled with the impression expiry. The max expiry that Chrome supports is 30 days. However, many consumers of the event level data may need this report sooner than that. To support that, we will have to set smaller impression expiry, but as a result of that we lose all conversions (even the aggregated ones) that happen after that shorter expiry period, hence impacting the reporting needs.

If we have max_event_reporting_window decoupled with the impression’s expiry, then we can get event level data sooner without sacrificing the coverage of Aggregate API.

Proposal
We propose to add a new optional field “max_event_reporting_window” in the impression registration JSON.
{
"source_event_id": "12340873456",
"destination": "[eTLD+1]",
"expiry": "[64-bit signed integer]",
"max_event_reporting_window": "[64-bit signed integer]",
"priority": "[64-bit signed integer]"
}

When Chrome determines expiry window for an event, it uses the “max_event_reporting_window” field, if available; Otherwise it falls back to “expiry” field

This proposal is in line with Chrome’s existing treatment of a given event’s eligibility for the two APIs “independently”.