A webhook and a message queue are both ways of transmitting data from one application to another, but they work in different ways and are best suited for different use cases.
A webhook is a mechanism that allows one application to send a message to another application in real-time. When something happens in the first application, it can trigger the webhook to send a message to the second application. This allows the two applications to communicate and share data in near real-time.
For example, imagine that you have a web-based shopping cart application and a payment processing application. When a customer places an order on your website, the shopping cart application can use a webhook to send a message to the payment processing application with the details of the order. The payment processing application can then use this information to process the payment and complete the transaction.
Webhooks are an effective method for sending a variable number of messages to one or more customers, regardless of the size of the customer base. They are resource-efficient because they only require resources when actively sending messages to a specific customer, and do not require maintaining active connections when there is no activity. Webhooks are based on the HTTP protocol, which makes them easy to use and integrate with other systems in the stack. However, they may not be as efficient as other methods when sending a high number of requests per second to a specific customer.
In contrast, a message queue is great if you're consistently sending a very high volume of messages to a few customers.
The advantage of using a message queue is that it decouples the two applications. This means that they don't have to be connected at the same time in order to communicate. The first application can add a message to the queue, and the second application can retrieve it at a later time when it is available.
Message queues are a great way to increase scalability and performance. Since the messages are stored in a queue, the sending and receiving applications can process them at their own pace. This means that the applications can handle a high volume of messages without performance degradation.
Webhook services that reach a certain scale will generally implement a message queue to help them handle high message volumes, retry failed deliveries, and increase reliability of the system.
In summary, if your service requires sending a very high volume of messages continuously to a small number of consumers, a message queue may be a good fit. However, if you are sending variable amounts of messages to a larger number of customers and prioritize self-service and low operational burden, webhooks may be a better choice.