A webhook is an HTTP-based event notification mechanism in which a source system sends an outbound HTTP POST request to a pre-registered target URL — the webhook endpoint — when a specified event occurs in the source system. The target automation receives the event notification in real time, without needing to periodically poll the source system to check for new events. Webhooks invert the typical data retrieval pattern: rather than the automation asking “has anything changed since I last checked?” on a schedule, the source system tells the automation “something has changed, here is what happened” at the moment it happens. This inversion makes webhooks the preferred trigger mechanism for event-driven, real-time automation where latency matters.
How It Works
The webhook integration pattern requires two configuration steps: the target automation registers a webhook endpoint URL — typically a publicly accessible HTTPS endpoint managed by the automation platform or a serverless function — with the source system, specifying the event types that should trigger a notification. When the specified event occurs in the source system (a ZATCA invoice status update, a new payment received in the banking system, an ERP purchase order approval), the source system sends an HTTP POST request to the registered endpoint. The request payload — in JSON or XML — contains event metadata and the data relevant to the triggered event. The automation platform receives the request, validates it (typically using a shared secret or HMAC signature included in the request headers), and triggers the configured automation flow.
Webhook security is critical in financial automation contexts. The endpoint must be HTTPS (TLS encrypted); requests must include a signature or shared secret that the automation validates before processing; and the endpoint must implement idempotency handling — the ability to process a repeated delivery of the same event without producing duplicate outcomes, because webhook delivery is at-least-once, not exactly-once.
Design Considerations
Webhook endpoint availability is a dependency that the webhook source system may not gracefully handle. If the target automation endpoint is unavailable when the source system attempts delivery — due to maintenance, a platform outage, or network issues — the source system’s retry behaviour determines whether events are lost. Different systems implement different retry strategies: some retry a fixed number of times with exponential backoff, some queue events for later delivery, and some consider the event dropped after the first failed delivery. The automation design must account for the source system’s retry behaviour and implement a fallback reconciliation process for any events that may have been lost during endpoint unavailability periods.
What Breaks in Production
The specific failure that most reliably produces duplicate transaction processing in webhook-triggered automation is missing idempotency handling on the automation endpoint. When a source system retries a webhook delivery — because the first delivery’s response was delayed and the source system treated it as a timeout — the automation processes the same event twice. In a payment posting automation, this produces a duplicate payment. In an invoice processing automation, it produces a duplicate invoice entry. Idempotency handling requires the automation to record a unique event identifier from the webhook payload and check that identifier against a processed event log before execution — rejecting re-delivered events that have already been processed. This check must be implemented explicitly; no automation platform handles it automatically.
How Loop Wise Solutions Designs for This
In webhook-triggered automation design, we implement idempotency handling as a standard requirement — recording the event ID and processing status in a durable store before processing begins, and checking for prior processing before any action is taken. We also design endpoint monitoring: the webhook endpoint availability is monitored, and any unavailability period triggers a reconciliation job that queries the source system for events that may have been missed during the downtime window.
