APIs are not the same as Webhooks. APIs follow a request-based model, where results are returned only when a request is explicitly made. In contrast, webhooks are event-based and deliver real-time updates as soon as the event changes state, without requiring a manual request.
Webhooks provide a mechanism for real-time communication, leveraging resource availability. Imagine a retail scenario where timely updates are critical for inventory management. Instead of constantly checking stock status, a more efficient setup involves registering interest with the inventory provider. Once the resource becomes available, a real-time notification is sent automatically, mirroring webhook functionality.
In this setup, the webhook provider configures a webhook to notify third-party app providers, such as ourselves, about changes in resource status. When the stock is replenished, the webhook provider immediately triggers an HTTP POST request to the configured URL, reaching the designated contact points (listeners). Then, third-party app providers can use the available resources as needed. The real-time webhook process works as follows:
- Resources become available (Event).
- The inventory provider notifies us (via listeners) instantly when stock is updated.
- We retrieve the resources (HTTP POST request fires as a callback).
- We use the resources as needed (third-party provider).
In contrast, using APIs for a similar process would not involve any automatic updates from the inventory provider. APIs work on a pull basis. A request must be made to receive a response. As a result, maintaining up-to-date information depends on regularly querying the API endpoint to check for changes.
For example, consider building an API for location-based services. To retrieve information about a specific location, your system would send a GET request to the servers each time the data is needed.
So, when we need information from a third-party provider, we initiate a GET request to their servers, such as requesting location data via a map API.
Simply put, webhooks are ideal when you need real-time updates triggered by specific events, while APIs are best suited for situations where you need on-demand access to the most recent data.
Understanding this distinction helps ensure you choose the right integration model based on your system's timing, responsiveness, and data freshness needs.