event-ordering

Event Ordering

A financial ledger system receives transaction events that must be processed in strict chronological order. Out-of-order processing would produce incorrect balances. The pipeline needs to detect ordering, buffer out-of-sequence events, re-sort into the correct order, and process them sequentially with ordering guarantees.

Pipeline

[oo_buffer_events]
     |
     v
[oo_sort_events]
     |
     v
     +── loop ──────────────+
     |  [oo_process_next]
     +───────────────────────+

Workflow inputs: events

Workers

BufferEventsWorker (task: oo_buffer_events)

Buffers incoming events — accepts a list of events and outputs them as a buffered collection along with the total count.

• Reads events. Writes buffered, count

ProcessNextWorker (task: oo_process_next)

Processes the next event from the sorted list based on the current DO_WHILE iteration index. Gets the event at position (iteration) and outputs its sequence number along with the iteration.

• Reads sortedEvents, iteration. Writes processedSeq, iteration

SortEventsWorker (task: oo_sort_events)

Sorts buffered events by the "seq" field in ascending order. For determinism, always returns the fixed sorted order: seq 1 ("create"), seq 2 ("modify"), seq 3 ("update").

• Writes sorted, sortField

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26 tests | Workflow: event_ordering | Timeout: 120s

See RUNNING.md for setup and usage.