I want to build a headless application which will query the DB in infinite loop and perform some operations in certain conditions (e.g. fetch records with specific values and when found launch e-mail sending procedure for each message).
I want to use Spring Boot as a base (especially because of Actuator to allow expose health-checks), but for now I used Spring Boot for building REST web-services.
Is there any best practices or patterns to follow when building infinite loop applications ? Does anyone tried to build it based on Spring Boot and can share with me his architecture for this case ?
Best regards.
What I'm using is a message broker and a consumer put at the spring boot application to do the job.
Do not implement an infinite loop yourself. Let the framework handle it using its task execution capabilities:
@Service
public class RecordChecker{
//Executes each 500 ms
@Scheduled(fixedRate=500)
public void checkRecords() {
//Check states and send mails
}
}
Don't forget to enable scheduling for your application:
@SpringBootApplication
@EnableScheduling
public class Application {
public static void main(String[] args) throws Exception {
SpringApplication.run(Application.class);
}
}
See also:
There are several options. My approach is to start a loop on an ApplicationReadyEvent, and abstract away the loop logic into an injectable service. In my case it was a game loop, but this pattern should work for you as well.
package com.ryanp102694.gameserver;
import com.ryanp102694.gameserver.service.GameProcessor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;
@Component
public class GameLauncher implements ApplicationListener<ApplicationReadyEvent> {
private static Logger logger = LoggerFactory.getLogger(GameLauncher.class);
private GameProcessor gameProcessor;
@Autowired
public GameLauncher(GameProcessor gameProcessor){
this.gameProcessor = gameProcessor;
}
@Override
public void onApplicationEvent(ApplicationReadyEvent event) {
logger.info("Starting game process.");
gameProcessor.start();
while(gameProcessor.isRunning()){
logger.debug("Collecting user input.");
gameProcessor.collectInput();
logger.debug("Calculating next game state.");
gameProcessor.nextGameState();
logger.debug("Updating clients.");
gameProcessor.updateClients();
}
logger.info("Stopping game process.");
gameProcessor.stop();
}
}