When build event-driven architectures, you find yourself using many different patterns, not just one. When you dive into EDA applications you see a mixture of point-to-point messaging, pub/sub, choreography, orchestration, maybe some event sourcing and much more…

I believe using these patterns together help build a resilient, available and scalable event-driven architecture.

Process Manager

• The orchestrator that manages a workflow or process
• We have to perform business logic, this encapsulates that
• Often events are triggered from process manager to other consumers
• Example of this is AWS Step Functions

Event Sourcing

• Store events and use this information to calculate state
• Downstream projections can use this to calculate their own view of world
• Change data capture popular to listen to changes
• Audit is great here, as you can see everything that is happening.
• Example is storing events into NoSQL DB like Amazon DynamoDB

Event Streaming

• Often used to process information in real time
• Examples seen with user interactions on some form of interface (e.g. clicks)
• Messages are put onto the stream, consumers pick where they want to listen
• Offsets are used by consumers to read messages from the stream.
• Example of this is Amazon Kinesis

Point-to-point messaging

• Send messages to a channel for downstream consumers to process
• Multiple consumers can pick up messages from queue for concurrent processing
• Highly scalable pattern
• Example of this is Amazon SQS

Change data capture

• React to changes when they are made against your data
• Listen for new, delete or updates
• Attach consumers to changes to process information
• Example of a DB that supports this is Amazon DynamoDB

#### Pub/Sub

• Fire notifications out to downstream consumers
• Fan out events
• Consumers get own copy of event
• Create for decoupling applications and scaling teams
• Example of this is Amazon EventBridge

Extra resources

• Point-to-point messaging - What is point-to-point messaging? When should you use it? Visual I created to help you
• Choreography vs orchestration - What’s the differnce? Using process managers to orchestrate workflows or using events to communicate between services, maybe a world of both? More than likekly…
• Pub/Sub - What is Pub/Sub? When do events get pushed to consumers? Why use this pattern? Visual here to help
• Event-driven architecture with domain-driven design - How does domain-driven design help us build event-driven architectures? Take a look to understand why.