# Common issues and best practices

This page explains commonly encountered issues during webhook deliveries and best practices to minimize these problems.

## Head-of-line blocking

Spotnana’s architecture is designed to isolate each partner’s subscriptions,
so that the performance of one partner endpoint will not affect the other.
However, as a best practice to avoid any out-of-order messages and interleaved transactions
due to [head-of-line blocking](https://en.wikipedia.org/wiki/Head-of-line_blocking),
we recommend you maintain responsive APIs with low latency.

## Retry mechanism

If your API responds with a status code other than `200 OK`,
our systems will mark the webhook delivery as failed.
This will initiate a retry attempt up to five times, with no specified time interval between each retry.

## Out-of-order messages

Some best practices to resolve any out-of-order message deliveries are:

- **Use the `timestamp` field:** This field indicates the time the message was generated by Spotnana. You can use the `timestamp` to determine the correct order in which the events occurred.
- **Design for idempotent operations:** Sometimes due to network issues or other rare scenarios, a message might be delivered multiple times. Ensure that your webhook processing logic is idempotent and capable of handling the same message multiple times. You can leverage the `operation` and the `timestamp` fields to design your code to be idempotent.
- **Process the entire `payload`:** Instead of performing a diff on the payload, it is recommended to process the entire payload for data consistency.


## Logging and tracing

To assist with debugging, Spotnana includes trace and span IDs in all
webhook requests as `X-B3-TraceId` and `X-B3-SpanId` headers, respectively.
Be sure to log these IDs and provide them to Spotnana support when reporting any issues.