Error Handling

Both SDKs map every non-2xx HTTP response to the same four categories, via the identical status-code rules described in Java Exceptions and Node.js Exceptions.

Category → recommended action

Category	Status codes	Recommended action
Auth	401, 403	Don't retry as-is. Check the key/secret you configured — see Authentication.
Validation	Other 4xx	Don't retry as-is. Fix the request based on the response body.
Rate limit	429	Retry after a delay, ideally with exponential backoff.
Server	5xx	Safe to retry with backoff — the failure is likely transient.
Network / local	N/A (status code 0)	Retry with backoff; this covers connection failures and local serialization errors.

Example: retry with backoff

Java

int maxAttempts = 3;
for (int attempt = 1; attempt <= maxAttempts; attempt++) {
    try {
        client.notifications().send(request);
        break;
    } catch (NotificationHubException.NotificationHubRateLimitException
             | NotificationHubException.NotificationHubServerException e) {
        if (attempt == maxAttempts) throw e;
        Thread.sleep((long) Math.pow(2, attempt) * 1000);
    }
}

Node.js

import { NotificationHubRateLimitError, NotificationHubServerError } from '@sumitshresht/notificationhub-sdk';

const maxAttempts = 3;
for (let attempt = 1; attempt <= maxAttempts; attempt++) {
  try {
    await client.notifications().send(request);
    break;
  } catch (error) {
    const retryable = error instanceof NotificationHubRateLimitError || error instanceof NotificationHubServerError;
    if (!retryable || attempt === maxAttempts) throw error;
    await new Promise((resolve) => setTimeout(resolve, 2 ** attempt * 1000));
  }
}

Idempotency and retries

When retrying a send, pass the same idempotency key on every attempt (see sendWithIdempotency) so a retry after a network timeout can't result in a duplicate notification if the original request actually succeeded server-side.

Related

• Java Exceptions
• Node.js Exceptions
• Troubleshooting