How to pass data from Spring backend to Angular frontend?

I know my question is a bit general, but I couldn't find anything on this. How do you pass data from the Spring backend to the Angular front end? What would be the best approach?

A quick example:

I want to develop a microservice to be integrated from other system. I want to provide a REST interface with which the user can trigger events in the frontend. Now when a user makes a REST request, how do I pass the message to the Angular frontend?

Frontend -> Backend REST

Backend -> Frontend ????

First you can define an endpoint with Spring Boot:

@GetMapping(value = "/test", produces = APPLICATION_JSON_VALUE)
public ResponseEntity<String> test() {
    return ResponseEntity.ok("Hello world");
}

For development you would need to turn off CORS:

@Profile("dev")
@Configuration
public class CorsConfiguration implements WebMvcConfigurer {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
            .allowedMethods("GET")
            .allowedOrigins("http://localhost:4200");
       }
}

and then you can easily subscribe on data in Angular method:

onClick(): void {
this.subscribed = this.http.get('http://localhost:8080/test', {responseType: 'text'})
      .subscribe(data => this.message = data);
}