toGroupKey

Converts a message exchange to a grouping key for parallel processing.

This extension function determines how message exchanges are grouped for parallel processing. Exchanges with the same key will be processed sequentially within their group, while different groups can be processed concurrently based on the parallelism level.

A good grouping strategy distributes load evenly across groups while maintaining ordering requirements. Common approaches include:

• Hash-based grouping for even distribution

• Aggregate ID-based grouping for per-aggregate ordering

• Round-robin assignment for simple load balancing