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Integration
Message Routing
Resequencer
Messages arrived out of order — buffer them and release in the correct sequence.
Intent & Description
Real-world Use Case
Financial transaction log replay — 1000 transaction messages are published in parallel but arrive out of order. Resequencer buffers and releases them in transaction-timestamp order. Downstream ledger receives events in the correct chronological order, maintaining balance integrity.
Source
📌 TL;DR
Resequencer = fix the order of async message delivery. Buffer out-of-sequence messages, release in order. Essential for anything that requires strict ordering guarantees.
Advantages
- Restores ordering guarantees that async delivery breaks
- Transparent to downstream processors — they see ordered messages
- Works without modifying producers or downstream consumers
- Pairs naturally with Message Sequence pattern
Disadvantages
- Buffering all out-of-order messages = memory pressure at high throughput
- A single missing message can block the entire sequence indefinitely
- Timeout strategy for missing messages must be tuned carefully
- Adds latency — messages wait in buffer until sequence is complete