Scatter

First half of the scatter-gather pattern: sends the same input message to every component connected to Output, in parallel, and tags each copy so that a Gather component can later combine the branch results into one message.

Pins

Pin	Kind	Types	Description
Input	input	any	The message to distribute.
Output	output	same as input	One copy of the input per output connection (branch).

Configuration

Field	Type	Default	Description
Timeout	integer (seconds, >= 0)	0	Maximum time for all branches to reach the Gather component. 0 = wait indefinitely.

Behaviour

• For every input, each connection on Output is one slot. The input is sent to all connections at the same time (each on its own task), with a copy of the metadata that carries the scatter information (Viaducta.Plugins.ScatterGather.Types.ScatterMetaData: slot id = connection id, plus a shared handler).
• The component waits until all branches have finished their processing before it completes.
• Gather emits the combined result when every slot has received one result.
• With Timeout > 0, a background check runs every second: if not all slots were filled in time, a recoverable timeout error ("The timeout occurred while waiting for gatherer to collect all of the inputs") is raised to the flow's error handling with the original input, and Gather ignores late results for that message.
• With no output connection nothing happens.

Notes

• Every branch must deliver exactly one message to Gather per input. A branch that filters the message out (or fails) leaves its slot empty, and Gather never emits - use Timeout to detect this. A branch that emits several messages fills the counter more than once.
• Each branch must end in a different component connected to Gather; Gather names its output properties after these components.
• The branch connections from Output should all lead (possibly through other components) to the same Gather.
• Very fast branches can finish before Scatter has registered all slots; in that case Gather may never complete. Set a Timeout in production flows.

Example

{ "Timeout": 30 }

Http listener → Scatter → (Http client "PriceService", Database reader "StockService") → Gather (OutputName = ProductInfo) → Http response