A webhook and a message queue are both ways of transferring data from one to another application.
Webhooks
A webhook allows that one application sends a message to another application in real-time. When something happens on 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.
As an example, imagine that you have a web-based shopping cart application and a payment processing application. When a customer places an order on the website, the shopping cart app can use a webhook to send a message to the payment app with the details of the order. The payment app can then use this information to process the payment and complete the transaction.
Webhooks are an effective way 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. However, they may not be as efficient as other methods when sending a high number of requests per second to a specific customer.
Message Queue
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.