CONTRACT-ORIENTED MODELLING OF MICROSERVICE ARCHITECTURE FOR HIGH-LOAD SYSTEMS IN A UML-LIKE ENVIRONMENT

Abstract

The study aims to develop and substantiate a contract-oriented modelling method for the microservice architecture of high-load software systems within a specialised UML-like web environment. The proposed approach merges the advantages of visual design and formal interface specification: JSON contract fragments are embedded directly into the arrows representing component interactions on the diagrams. This provides an early, unambiguous and machine-readable fixation of API agreements, minimises the gap between the design model and service implementation, and reduces documentation- maintenance costs.Methodology. The method includes an algorithm that automatically converts the embedded JSON contracts into OpenAPI v3 specifications, which can then be used to generate server stubs, client libraries, integration tests or configure API gateways. A prototype of the environment was implemented with a TypeScript + Node.js stack, combining Canvas/WebGL diagram rendering with a server-side OpenAPI generator. Experimental evaluation on three representative scenarios (product catalogue, order service, payment service) compared the proposed approach with a classical UML-based process that lacks contracts. The results demonstrated a 28 % reduction in average API alignment time, a 33 % decrease in integration defects and a 22 % improvement in documentation coverage. Scientific novelty. A distinctive advantage of the tool is its support for «living» documentation: any change in the diagram is instantly mirrored in the updated contract, ensuring synchronisation between the model and service source code throughout the software life-cycle. Future research will focus on integrating the environment with real-time contract-tracing systems, extending support for asynchronous protocols (AsyncAPI) and developing metrics for assessing the complexity of contract dependencies across an enterprise-scale service portfolio.Conclusions. The proposed contract-oriented modelling method within a UML-like environment has proven effective for high-load microservice systems. Automatic OpenAPI generation and live documentation support shorten API alignment time, reduce integration defects and increase documentation coverage. The tool maintains continuous consistency between the architectural model and service code, thereby enhancing software quality and simplifying its evolution and maintenance.