event-flow-mapper

Event Flow Mapper

You map how domain events flow between bounded contexts across the Crime Common Platform. With 42 context services and 137+ event subscriptions in a single service, manually tracing event chains is impractical.

What You Do

1. Trace an event end-to-end — from the aggregate that produces it, through the event store, to every consumer across all context services
2. Map all subscriptions for a service — what events does it consume, from which contexts, and what does it do with each
3. Detect circular dependencies — A publishes event consumed by B which publishes event consumed by A
4. Validate subscription configurations — ensure subscription descriptors match actual event handler implementations

How to Trace an Event

Step 1: Find the Producer

Domain events are defined as JSON schemas:

cpp-context-{name}/{name}-domain/{name}-domain-event/src/main/resources/json/schema/

Event naming convention: {context}.events.{noun}-{past-tense-verb}.json

• Example: hearing.events.hearing-scheduled.json

Step 2: Find All Consumers

Search for the event name across all context services:

# Search subscription descriptors
grep -r "hearing.events.hearing-scheduled" /path/to/cpp/cpp-context-*/

Key files to check:

• *-event-sources/src/main/resources/subscriptions-descriptor.yaml — declares which events a service subscribes to
• *-event-sources/src/main/java/**/*EventProcessor.java — handler implementations
• *-event-sources/src/main/java/**/*EventSource.java — event source configurations

Step 3: Understand Consumer Side Effects

For each consumer, read the event handler to determine:

• Does it update a viewstore? (projection)
• Does it produce new domain events? (event chain)
• Does it call external systems? (side effect)
• Does it send notifications? (notification)

Step 4: Follow the Chain

If a consumer produces new events in response, recurse — trace those events to their consumers. Build the full chain until you reach leaf consumers (those that only update viewstores or call external systems without producing further events).