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straightface

•Created by straightface on 2/1/2025 in #java-help

Backoff and retry for parallel api calls

I have a list of objects that i make parallel api calls and store the result in database. But the problem I am having now is the api goes down and subsequent calls fails I am not sure how I should implement backoff and retry since these are parallel calls I have already executed those

  @Async
  public CompletableFuture<String> apiCall(String payload){
     ...    resttemplate
     return CompletableFuture.completedFuture(..);
  }

// Calling class
  
  public List<String> getResponses(List<String> payloads){
  List<CompletableFuture<String>> futures = new ArrayList<>(); 
  for(String payload : payloads){
     futures.add(apiService.apiCall(payload));  
  }

  return futures.stream()
         .map(CompletableFuture::join)
         .toList(); 
}

  @Async
  public CompletableFuture<String> apiCall(String payload){
     ...    resttemplate
     return CompletableFuture.completedFuture(..);
  }

// Calling class
  
  public List<String> getResponses(List<String> payloads){
  List<CompletableFuture<String>> futures = new ArrayList<>(); 
  for(String payload : payloads){
     futures.add(apiService.apiCall(payload));  
  }

  return futures.stream()
         .map(CompletableFuture::join)
         .toList(); 
}

4 replies

JCHJava Community | Help. Code. Learn.

•Created by straightface on 2/3/2024 in #java-help

RMI calls in CompletableFuture stream

is it safe to call rmi service using CompletableFuture like so

Registry registry = null;
        try {
            // Locate the RMI registry and obtain a reference to the remote object
            registry = LocateRegistry.getRegistry("your_server_hostname", 1099);
        } catch (Exception e) {
            e.printStackTrace();
        }
        PersonService personService = (PersonService) registry.lookup("PersonService");
        // Use CompletableFuture to perform RMI calls in parallel
        List<Person> lastNameFutures = personList.stream()
                .map(person -> CompletableFuture.supplyAsync(() -> { 
          person.setCompletableName(personService.getLastName(person)
          return person;
}
), executorService))
                .collect(Collectors.toList());

Registry registry = null;
        try {
            // Locate the RMI registry and obtain a reference to the remote object
            registry = LocateRegistry.getRegistry("your_server_hostname", 1099);
        } catch (Exception e) {
            e.printStackTrace();
        }
        PersonService personService = (PersonService) registry.lookup("PersonService");
        // Use CompletableFuture to perform RMI calls in parallel
        List<Person> lastNameFutures = personList.stream()
                .map(person -> CompletableFuture.supplyAsync(() -> { 
          person.setCompletableName(personService.getLastName(person)
          return person;
}
), executorService))
                .collect(Collectors.toList());

Notice i am mutating person object and saving future in Person

7 replies

JCHJava Community | Help. Code. Learn.

•Created by straightface on 4/7/2023 in #java-help

Should I be storing dates in utc?

Lets say I have a venue booking form that requires start date and end date for an event, users can only book full day events. So should I be storing these dates in utc or local time?

10 replies

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