springspring-batchspring-cloud-dataflowspring-cloud-task

Schedule simple GET batch for each second or even less than one second - Should opt for Spring Cloud Task, Spring Batch or springframework.scheduling


Context: in my country there will be a new way to Instantly Payment previewed for November. Basically, the Central Bank will provide two endpoints: (1) one POST endpoint which we post a single money transfer and (2) one GET endpoint where we get the result of a money transfer sent before and it can be completely out of order. It will answer back only on Money Transfer result and in its header will inform if there is another result we must GET. It never informs how many results are available. If there is a result it gives back on Get response and only inform if it is the last one or there is remaining ones for next GET.

Top limitation: from the moment final user clicks Transfer button in his/her mobile app until final result showing in his mobile screen if it was successful or failed is 10 seconds.

Strategy: I want a schedule which triggers each second or even less than a second a Get to Central Bank. The Scheduler will basically evoke a simple function which

  1. Calls the Get endpoint
  2. Pushes it to a Kafka or persist in database and
  3. If in the answer headers it is informed more results are available, start same function again.

Issue: Since we are Spring users/followers, I though my decision was between Spring Batch versus org.springframework.scheduling.annotation.SchedulingConfigurer/TaskScheduler. I have used successfully Spring Batch for while but never for a so short period trigger (never used for 1 second period). I stumbled in discussion that drove me to think if in my case, a very simple task but with very short period, I should consider Spring Cloud Data Flow or Spring Cloud Task instead of Spring Batch.

According to this answer "... Spring Batch is ... designed for the building of complex compute problems ... You can orchestrate Spring Batch jobs with Spring Scheduler if you want". Based on that, it seems I shouldn't use Spring Batch because it isn't complex my case. The challenge design decision is more regard a short period trigger and triggering another batch from current batch instead of transformation, calculation or ETL process. Nevertheless, as far as I can see Spring Batch with its tasklet is well-designed for restarting, resuming and retrying and fits well a scenario which never finishes while org.springframework.scheduling seems to be only a way to trigger an event based on period configuration. Well, this is my filling based on personal uses and studies.

According to an answer to someone asking about orchestration for composed tasks this answer "... you can achieve your design goals using Spring Cloud Data Flow along with the Spring Cloud Task/Spring Batch...". In my case, I don't see composed tasks. In my case, the second trigger doesn't depend on result from previous one. It sounds more as "chained" tasks instead of "composed". I have never used Spring Cloud Data Flow but it seems a nice candidate for Manage/View/Console/Dashboards the triggered task. Nevertheless, I didn't find anywhere informing limitations or rule of thumbs for short periods triggers and "chained" triggers.

So my straight question is: what is the current recommend Spring members for a so short period trigger? Assuming Spring Cloud Data Flow is used for manager/dashboard what is the trigger member from Spring recommended in so short trigger scenarios? It seems Spring Cloud Task is designed for calling complex functions and Spring Batch seems to add too much than I need and org.springframework.scheduling.* missing integration with Spring Cloud Data Flow. As an analogy and not as comparison, in AWS, the documentation clear says "don't use CloudWatch for less than one minute. If you want less than one minute, start CloudWatch for each minute that start another scheduler/cron each second". There might be a well-know rule of thumb for a simple task that needs to be trigger each second or even less than one second and take advantage of Spring family approach/concerns/experience.


Solution

  • This may be stupid answer. Why do you need scheduler here?. Wouldn't a never ending job will achieve the goal here?