@nestjs/microservices/interfaces/message-handler.interface.d.ts

import { Observable } from 'rxjs';
/**
 * @publicApi
 */
export interface MessageHandler<TInput = any, TContext = any, TResult = any> {
    (data: TInput, ctx?: TContext): Promise<Observable<TResult>> | Promise<TResult>;
    next?: (data: TInput, ctx?: TContext) => Promise<Observable<TResult>> | Promise<TResult>;
    isEventHandler?: boolean;
    extras?: Record<string, any>;
}