Most people would have encountered the term “webhook” in application settings. Webhooks come into the picture when an action is triggered in an application, anad if it has to be conveyed to another application. They are called webhooks because they are sequences of software hooks that operate on the web.
Webhooks send automatic messages or transfer information from one app to another. Their functions are similar to the SMTP relay service, which transfers email messages from one server to another and reaches the recipient’s inbox.
An SMTP relay service requires a domain name and DNS to reach out to the recipient’s email, while webhooks require the URL of the receiving app. Email marketing apps and webhooks are becoming popular and effective tools for maintaining high business efficiency and customer satisfaction.
Application and working of Webhooks
A few real-time examples of webhooks can be an online food delivery app (A). Once the order is placed, you get redirected to an online payment app (B). Here the message is passed from app A to app B. Meanwhile, when the payment is made, app B will send a confirmation message to app A. The amount debited will be communicated from customer app B to the bank’s mobile application, say app C. Hence any automatic data transfer involves webhooks.
There’s no external trigger required in webhooks, unlike polling, where there is a request-and-send kind of information transfer. Polling and webhooks are two major ways for any two applications to communicate. Polling involves a lot of human intervention and works, while webhooks don’t. Webhooks are also faster than polling while commuting from one app to another.
While APIs are generally associated with webhooks, they differ because of the pulling and pushing concepts like polling and webhooks. Though webhooks are called reverse APIs, it is not entirely true.
Data is pulled continuously from the server periodically in an API to make sure that an event has occurred. In a webhook, the sender’s server will notify once the event has occurred. Webhooks are more productive and cost-effective.
Technically speaking, webhooks are “user-defined HTTP callbacks.” An HTTP request is made to the required URL, and events are triggered. A digital signature can be added to maintain the integrity of the data.
The receiving application generally sends a call back in the form of HTTP codes to acknowledge the success of the communication or a sensor 404 error message. The messages that the webhooks carry are called payloads.
Setting up Webhooks
Step 1: Obtain the URL from the application to which the information has to be sent.
Step 2: In the receiver side application, place the obtained URL from step 1 in the webhook’s URL section and go to the settings menu.
Step 3: In the settings, we can choose the type of communication that has to be automatically triggered when hit and notification settings are also made. It can be an alert message, a transaction notification, or a notification of unsubscription.
Despite webhooks being popular, some apps don’t have the connectivity to integrate them. Here, middleware that supports webhooks through API polling can be used. As webhooks are becoming more popular, it will be easy to understand them while working hands-on.