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Request Attempts

A request attempt represents a single delivery attempt for a webhook. When an event matches a subscription, Hook0 creates a request attempt and tracks its lifecycle from creation to successful delivery or final failure.

Key Points​

  • Each event/subscription pair generates one or more request attempts
  • Hook0 automatically retries failed deliveries with exponential backoff
  • Request attempts transition through distinct statuses
  • Full delivery history is available for debugging

Delivery Lifecycle​

Event Created
    |
    v
+-------------------+
|     PENDING       | <- Queued for delivery
+-------------------+
    |
    v
+-------------------+
|   IN_PROGRESS     | <- Being delivered
+-------------------+
    |
    +-------+-------+
    |               |
    v               v
+----------+  +----------+
|SUCCESSFUL|  |  FAILED  |
+----------+  +----------+
                   |
                   v (if retries remaining)
              +----------+
              | WAITING  | <- Backoff delay
              +----------+
                   |
                   v
              (retry cycle)

Status States​

Request attempts transition through these states:

  • Pending - Queued and waiting to be picked up for delivery
  • In Progress - Currently being delivered to the endpoint
  • Waiting - Delivery failed, waiting for retry (backoff delay)
  • Successful - Webhook delivered and endpoint returned 2xx
  • Failed - All retry attempts exhausted or permanently failed

Retry Behavior​

When a delivery fails, Hook0 automatically schedules retries with exponential backoff:

  1. First failure → Short delay
  2. Subsequent failures → Progressively longer delays
  3. After max retries → Marked as permanently failed

This ensures transient failures don't cause data loss while avoiding overwhelming struggling endpoints.

Failure Scenarios​

Request attempts fail when:

  • Endpoint returns 4xx or 5xx status codes
  • Connection times out
  • DNS resolution fails
  • SSL/TLS handshake fails
  • Application is deleted (all pending attempts cancelled)

Debugging Failed Webhooks​

When webhooks fail, request attempts provide:

  • Timestamps - When each phase occurred
  • Retry count - How many attempts were made
  • Response reference - Link to the endpoint's response

This information helps identify:

  • Endpoint availability issues
  • Authentication problems
  • Payload processing errors

What's Next?​