External event that provokes action across multiple aggregates

[makp0]

The question in the title has been haunting me for a while. Don't recall stumbling upon anything related to that.

Given we have an eventuous-driven system which makes orders based on external market data. Events from that external market system are completely unaware of our system.

Incoming event:
record MarketEvent(int updatedValue);

Simplified method in a generic class that is subscribed to external marked data:

void HandleEvent(MarketEvent evt)
{
  _commandService.Handle(new UpdateDataCommand(/* here should be an aggregate id of an aggregate that should react , but where to get it? */ ));
}

To keep it simple let's suppose we are not filtering aggregates, meaning all aggregates are interested in the event. We still need all aggregate ids.

• Use IAggregateStore? But Load method requires a StreamName which contains an aggregate id.
• Use Read Model to get all aggregate ids?

[makp0]

@alexeyzimarev, could you please share your approach?