Devevopment of a method for improving maintainability of microservice software based on centralized outgoing event management
This study investigates the process of managing output events in microservice systems where business logic is isolated from infrastructure dependences and events are transmitted asynchronously by external event transport mechanisms. The task addressed relates to the lack of a holistic architectural method for isolating business logic from event transport mechanisms. As their number increases, the application code becomes more complicated, its testability deteriorates, and technical debt also increases. This work reports a method developed for centralized management of output events, consisting of six components (Key, Info, RoutingRule, EventContract, EventDispatcher, EventManager). It provides complete isolation of business logic from event transport mechanisms through declarative routing rules and dependence inversion. This method supports conditional and multicast routing without the need to make changes to the application code. The method is defined through abstract interfaces and is independent of the programming language by default. Its effectiveness has been confirmed on six control projects with a 2 × 3 design: two implementations (baseline and proposed) at three levels of complexity. Applying the method to a project with three event transport mechanisms and fifteen use cases provides an increase in the use case maintainability index by 4.9 points (5.5%). Halstead effort is reduced by 47%, technical debt by 14.7%, average cyclomatic complexity by 28%; features with excessive cyclomatic complexity are absent compared to the baseline implementation. The applicability hypothesis has been empirically confirmed: the method is appropriate for microservices with more than two event transport mechanisms or more than ten use cases that generate events