Exploring different types of events

When building EDA applications, it’s important to know the different types of events you can publish, each has their own trade-offs.

Event Carried State Transfer Events

• Enriched events (stateful)
• Higher risk of data being out of sync
• Consumers have the data
• Decreases architecture coupling
• Producer/consumer contracts more coupled
• Higher risks of breaking contracts

Notification Events

• Minimal information
• Less risk of data being out of sync
• Consumers often need to fetch data
• Increases architecture coupling (callback for info)
• Producer/Consumer contracts kept minimum
• Lower risk of breaking contracts

Delta Events

• Stores difference between old/new
• Examples seen in change data capture events
• Can reduce complex in consumers needing to figure out what has changed

Domain Events

• Events that raised in the same bounded context
• Some team reference these as internal events raised in bounded context
• Some team reference these as business “important” events.
• People also refer to “integration” events. These are events used for integrations.