The paper examines the problem of gradually migrating a monolithic backend application to a microservice architecture. The relevance of the study is determined by the limitations inherent in monolithic architectures that emerge as enterprise information systems grow, including high component coupling, the need to scale the system as a whole, limited opportunities for independent deployment of individual components, and the dependence of core business scenarios on external services. The aim of the study is to analyze architectural patterns for gradual migration from a monolithic to a microservice architecture and to develop a methodology for evaluating migration effectiveness using the integration of a PHP/Yii2-based monolith with a service developed in Go as an example. The study employs architectural and comparative analysis, experimental testbed design, and load testing methods. The Strangler Fig approach was selected as the migration strategy, combined with the API Gateway/Reverse Proxy, Anti-Corruption Layer, Outbox, and Circuit Breaker patterns, as well as idempotency mechanisms. The first migration stage involves extracting the notification module into a separate Go service. Order creation and event recording in the Outbox table are performed within a single local transaction, while the actual delivery of notifications is carried out asynchronously. To compare the monolithic and target configurations, an experimental testbed based on Docker and a k6-based load testing methodology were developed. The evaluation criteria include p50, p95, and p99 response-time percentiles, throughput, error rate, and system resilience in the event of a dependent component failure. The results of the study provide a methodological basis for organizing gradual migration as an alternative to a complete system rewrite. A full-scale load experiment and its statistical analysis will be conducted at the next stage of the research.

TIMOSHENKO R.A.

Master's student, Karaganda technical university named after Abylkas Saginov, Karaganda, Kazakhstan.

E-mail: rombik2004r@gmail.com, https://orcid.org/0009-0004-4099-8220

BIGALIYEVA A.Z.

PhD, associate professor, Abylkas Saginov Karaganda technical university, Karaganda, Kazakhstan

E-mail: bigalievaalfija@gmail.com, https://orcid.org/0000-0002-0136-5402

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monolithic architecture, microservice architecture, gradual migration, Strangler Fig, Outbox pattern, PHP, Go