Per-order ordered parallelism method in microservice event delivery systems

DOI: 10.31673/2412-9070.2025.061213

Abstract

This paper presents a per-order ordered parallelism method for event delivery in microservice-based architectures, designed to ensure strict execution order within each logical workflow while sustaining high throughput and fault tolerance. The proposed approach introduces an application-level ordering layer built atop the RabbitMQ message broker, avoiding any modification of broker internals. The method relies on per-event sequence identifiers (X-Sequence-ID), dynamic per-key queue instantiation, and a gap-replay mechanism for recovering missing states, thereby providing deterministic processing and reliable restoration of system state even under message loss or redelivery.
The scientific contribution consists in the development of a formal execution model that integrates at-least-once delivery semantics, idempotent event handling, controlled redelivery, and bounded buffering. An analytical model is constructed to quantify the influence of parallelism on system latency, throughput, and stability, taking into account probabilistic message loss, queue load factors, resource constraints, and fallback HTTP channels. This model enables formal evaluation of the system overhead ε and predictive assessment of behavior during broker degradation, partial failures, or system updates, offering a mathematically substantiated basis for tuning concurrency and recovery mechanisms.
Experimental evaluation within the AutoGivex microservice ecosystem demonstrates reduced processing latency, increased stability, and improved scalability compared to traditional broker-level ordering strategies. The results confirm that the proposed method provides a robust foundation for building resilient event-driven distributed systems that require strict per-order consistency, deterministic behavior, and adaptive throughput optimization. The findings can be applied to a wide range of domains—financial, logistics, enterprise, and real-time platforms — where correctness and reliability of event sequencing are essential.

Keywords: ordered parallelism; microservices; event delivery; RabbitMQ; X-Sequence-ID; idempotency; gap-replay; concurrency model; fault tolerance; analytical model; AutoGivex information technology.