SUB Command

Syntax

SUB;CLIENT_ID=client_id;EVENT_NAME=event_type

Parameter	Description	Required	Example
CLIENT_ID	ID of the client subscribing to events	Yes	`client-123abc`
EVENT_NAME	Type of event to subscribe to	Yes	`user/profile/updated`

+PASS:SUBSCRIBED;EVENT_NAME=user/profile/updated

The response confirms that the subscription was successful and includes the event name that was subscribed to.

-FAIL:MISSING_PARAMETERS;MESSAGE=Missing required subscription request. Ensure CLIENT_ID, EVENT_NAME are passed

-FAIL:PERMISSION_DENIED;MESSAGE=Not authorized to subscribe to this event type

-FAIL:CLIENT_NOT_FOUND;MESSAGE=Invalid client ID

SUB;CLIENT_ID=client-123abc;EVENT_NAME=user/profile/updated

Subscribe to all events in a domain:

SUB;CLIENT_ID=client-123abc;EVENT_NAME=order/*

Event names follow a hierarchical path-like structure (e.g., domain/resource/action)
Wildcards can be used to subscribe to multiple event types (e.g., order/* subscribes to all order events)
Clients can subscribe to multiple event types by sending multiple SUB commands
When a client subscribes to an event type, it will immediately begin receiving any new events of that type
The system will check if the client has the necessary permissions to subscribe to the requested event type
Multiple instances of the same service can subscribe to the same event types, implementing the competing consumer pattern
Each instance will receive a unique client ID to track its subscriptions and event processing state

Last modified: 07 October 2025