Communication is critical in programming, just like it is for humans. Both software and hardware applications communicate with other entities to perform correctly and efficiently. From a browser communicating with the server to return a correct response to the user to home security systems getting the user's preference settings from the cloud to perform the necessary task after detecting a break-in.

In this article, you will learn about webhooks, how they differ from other web communication technologies, how to use them to create effective event-driven applications, and so much more. You will also explore how popular services are using webhooks services to help both small and large businesses grow and thrive.

Let's look at what webhooks are in the next section.

Webhooks

Webhooks are a powerful concept in modern web development that allows applications to communicate with each other in a real-time, event-driven manner. In simple terms, a webhook sends automated HTTP requests from one application to another when a specific event occurs. It enables real-time data transmission and facilitates seamless integration between different systems.

Webhooks are revolutionizing the way applications communicate with each other. They automate workflows, enhance overall system performance, and provide a convenient way for systems to send notifications and trigger actions between different applications or services.

Webhooks can be used to build complex distributed systems ranging from platforms handling payments and shipping automation on your e-commerce website to deploying your applications with GitHub. For example, many deployment platforms leverage webhooks to enable developers automatically deploy their applications after pushing code to GitHub. We'll see more use cases of webhooks later in this article.

The World Before Webhooks

In today's interconnected world, where data flows seamlessly between different platforms and systems, it's hard to imagine a time when such integrations were not the norm. However, there was indeed a time when transferring data between applications was a complex and time-consuming process. This was the world before webhooks.

In the past, before the advent of webhooks, developers relied on a variety of methods to transfer data between systems. Let's explore some of the notable techniques and the challenges they pose.

Polling

One standard method was polling, where an application repeatedly queries another application for new data. For example, an application might periodically check an email server for new messages. This approach had significant drawbacks, including the waste of resources as applications had to continually send requests, even when no new data was available. It also resulted in delays between data updates, as the system had to wait for the next polling interval.

Messaging Queues

Some systems use messaging queues to enable communication between applications. In this approach, applications would send messages to a central queue, and other applications would read these messages and process them accordingly. While messaging queues improved data transfer efficiency compared to polling and can be used for event-driven architecture among microservices, they're unsuitable for event-driven architectures over the internet. For example, integrating Stripe events with message queues would be too complex.

Remote Procedure Calls (RPC)

RPC is a synchronous communication mechanism, but it can also be used to achieve asynchronous communication by implementing callback functions or using futures and promises. With callbacks, the client initiates a request and provides a callback function that the server invokes when the result is ready. Futures and Promises allow the client to request a result and receive a future object immediately. The client can then periodically check the future object for completion or attach callbacks to handle the result when it becomes available. However, RPC is designed to handle synchronous communication, and forcing it to handle asynchronous scenarios might feel unnatural and can lead to scalability and flexibility issues.

Scheduled Jobs

Scheduled jobs were another way to transfer data between applications. These jobs would run at predefined intervals and perform specific tasks, such as fetching data from one application and pushing it to another. However, scheduled jobs suffered the same drawbacks as polling, such as delays in data updates and wasted resources when no new data was available.

Polling Optimization

To reduce the impact of frequent polling, developers implemented techniques like long-polling. These methods involved keeping the connection open until new data was available, minimizing the number of requests made to the server. While this improved real-time updates to some extent, it still had drawbacks, such as increased server load and higher latency.

Comet Servers

Developers also experimented with the concept of Comet servers, designed to handle many long-lived server-to-server connections. These servers employed event-driven architectures, allowing them to efficiently manage real-time data updates and notifications. However, the reliance on specialized infrastructure and implementation complexity limited widespread adoption.

These methods, while functional to some extent, were far from ideal. They often led to inefficient use of resources, delays in data updates, and increased complexity for developers. Then came the advent of webhooks, which revolutionized how applications communicated and shared data.

How Webhooks Work

To understand how webhooks work, it is essential first to grasp the basics of the client-server communication model. In this model, clients send requests to servers, and servers respond with the requested data.

Webhooks offer an alternative approach to the techniques listed above. Instead of clients continuously querying servers for updates, webhooks allow servers to push data to clients in real time. This is particularly useful in event-driven architectures, where applications must react to specific events or triggers.

When a specific event occurs, the server initiates an HTTP POST request to the webhook URL provided by the client. The client, in turn, listens for these incoming requests and performs the necessary actions based on the received data. This asynchronous communication model eliminates the need for clients to make frequent requests, reducing unnecessary network traffic and improving system efficiency.

Pro-Tip

Note: An HTTP POST request is a standard request type for webhooks, but some companies expose a GET request.

Comparison with Traditional Polling Mechanisms

Let’s explore how webhooks differ from other techniques that try to solve the same problem:

The table above highlights the advantages of webhooks over alternative solutions in terms of real-time updates, server load, latency, standardization, implementation requirements, event-driven architecture, data transmission, and system performance.

Let's look at how webhooks differ from APIs in the next section.

Webhooks as Reverse APIs

In the world of web development, APIs have long been the standard method for applications to interact with each other. APIs enable the exchange of data and functionality between different software systems, facilitating integration and enabling developers to build robust and interconnected applications. However, as technology advances and real-time communication becomes increasingly important, a new approach has emerged: Webhooks.

Webhooks are considered to be reverse APIs because they flip the traditional client-server communication model. With APIs, the client initiates requests and pulls data from the server as needed. In contrast, webhooks allow the server to push data to the client in near real-time and as soon as the data is ready. This reverse approach enables event-driven communication and eliminates the need for constant polling from the client side.

By reversing the API model, webhooks provide numerous advantages. They enable applications to respond instantly to events, reducing delays and improving system responsiveness. This is especially crucial in scenarios where real-time updates are essential, such as live chat applications, collaborative tools, or stock market monitoring systems.

Webhooks, as event-driven systems, enable real-time updates, streamlined workflows, and enhanced user experiences. By harnessing the power of events, webhooks provide instant notifications and data payloads, allowing the applications to respond to real-time changes. This event-driven approach enhances responsiveness, scalability, and integration capabilities, empowering developers to create dynamic and interactive applications.

Conclusion

Thank you so much for reading! I hope this article achieved its aim of giving you a proper and detailed introduction to the world of webhooks. You learned how webhooks work, and how they compare to other web communication techniques.

If you got this far into this article, check out how Convoy can help you securely send, receive, and manage webhooks by providing you with features like rate limiting, static IPs, circuit breaking, rolling secrets, and much more.