Registrator
A Registrator is a helper object that manages the lifecycle of message bus registrations in a structured way.
In Postboy, it is used to group related registrations together and make sure they can later be cleaned up correctly. This is especially useful when an application has many messages, subscriptions, executors, or namespaces that should be created and removed as a unit.
What a Registrator is for
Registrators help you:
group related registrations in one place
keep setup logic separate from business logic
manage startup and teardown consistently
avoid leaving stale subscriptions or message bindings behind
Why it matters
In event-driven systems, the biggest problems often appear not when something is registered, but when it is not removed correctly.
If subscriptions, handlers, or message bindings remain active after they are no longer needed, the result can be:
memory leaks
duplicate reactions
unexpected message handling
hard-to-debug application state
Registrators help prevent that by keeping registration and cleanup paired together.
How Registrators work in Postboy
A Registrator usually performs two main tasks:
registration — connecting messages, executors or handlers to the bus
cleanup — disconnecting and disposing everything that was registered
This makes the lifecycle of communication flows much more predictable.
Key characteristics
A good Registrator in Postboy is typically:
structured — it collects related setup operations together
lifecycle-aware — it supports both initialization and teardown
safe — it helps avoid accidental leftover bindings
composable — it can manage multiple related services or flows
When to use a Registrator
Use a Registrator when:
your module needs to register several messages or executors at once
you want a clean start/stop lifecycle for a feature
you are building a larger application with dynamic message wiring
you want to make cleanup explicit and reliable
Registrator vs manual registration
Manual registration can work for small cases, but it becomes risky as the system grows.
A Registrator gives you a single place where you can see:
what was registered
when it was registered
how it gets removed
That makes the system easier to maintain and much less likely to accumulate hidden subscriptions.
In short
Registrator is Postboy’s lifecycle helper for bus configuration.
It helps manage registration and cleanup together, reducing leaks, accidental leftovers, and architectural chaos.