Start and keep running

A flow either runs once and stops, or keeps running and waits for work. The components you place decide which.

What runs when a flow starts

When a flow starts, it calls every component whose start or input pin is unconnected and needs no data. A Timer starts its schedule, an Http listener opens its port, a Kafka subscriber connects, and a Try catch or a script with nothing in front of it runs once.

Flows that keep running

A flow keeps running while it holds a component that waits for work. These plugins keep it running:

Category	Plugins
Flow	Timer, Fork
Web	Http listener, Web socket listener, Web socket client
Event	Kafka, MQTT and NATS subscribers and publishers
Network	TCP server, UDP server
Pipes	Pipe listener
Messaging	Sms receiver, Ussd server
Text	RSS/Atom parser

A flow published as a plugin also keeps running, so it is ready whenever another flow calls it.

Flows that run once

A flow without such a component runs its start components, and stops when they return. Use this for one-off jobs: a migration, a load, a test run.

Script (runs once) → Sql query → CSV encoder → Write file

To keep such a flow running anyway, for example because a script starts its own background work, switch on Keep alive in the flow configuration.

When a flow starts

The start mode in the designer toolbar decides whether the flow starts on its own:

Mode	The flow starts
Manual	Only when someone starts it, or a Start flow component starts it
Auto	Every time the controller starts
Disabled	Never

For Auto flows, Modify auto start dependencies picks the flows that must be running first.

Stop a flow

Stop a flow in the designer or from the Environment explorer. A flow also stops when a record has nowhere to go: see When nothing matches.