It’s common for services and applications to be required to communicate with one another and share information, whether on a server-to-server or server-to-client basis. Webhooks and WebSockets are two popular methods of end-to-end communication. With two different approaches, each method has its ideal use case.

WebSockets are primarily used for two-way communication between a server and a client, such as a web server and a browser. WebSockets keep a connection open between the server and the client so information can be sent back and forth between the two. The WebSocket protocol, which most browsers support, defines a standardized way for this communication to take place, usually by opening a connection over the Transmission Control Protocol (TCP).

Webhooks work slightly differently. Commonly used for one-way server-to-server communication, webhooks use regular HTTP to send requests from one server to another. A source service can send requests containing data to a destination service using a webhook URL provided by the destination service. The destination service then must then implement logic to accept the HTTP request and process it accordingly.

Now that you understand how webhooks and WebSockets work, let’s delve into their key differences and use cases so you know when to use webhooks versus WebSockets.

Webhooks Versus WebSockets

The primary difference between Webhooks and WebSockets is the method of communication each uses. Because webhooks are primarily used for one-way communication, while WebSockets are primarily used for two-way communication between a client and server, each communication method is best suited to a particular kind of task.

Webhooks are useful when you want to be notified about an event occurring in a particular system, like a status change or an update to a specific entity. You can provide the system with a webhook URL and choose which events you’re interested in. This event in the source system can then trigger an HTTP request to be sent to the given webhook URL. The consumer builds a service with HTTP endpoints that can accept the incoming requests made by the webhook service, parse the request, and process any data. The communication flows one way — from source to destination — and the socket is closed after each request.

WebSockets are useful when two-way communication is required, usually between a client and server, but also for server-to-server communication. The WebSocket is set up on the server and the client then connects to it. The initial request from the client is an HTTP handshake request, which is upgraded to a WebSocket connection if it’s valid. Both client and server can send messages via the WebSocket and each must implement message listeners, called when a message is received. This allows the message to be processed and, if necessary, a response to be made. The connection remains open for as long as required and is closed upon completion. 

The main advantage of webhooks is that the client can send messages back to the server. However, because WebSockets open a connection between a specific client and server, they make the server stateful (as it now contains the active connection), and therefore more difficult to scale.

Let’s look at some use cases for each to understand when and why you would use one over the other.

Webhooks Use Case

Webhooks are great for keeping track of changes in an external service, like tracking added or modified transactions in an account. They’re also helpful to both the service providing the webhook and the downstream consumer. Additionally, webhooks are inherently stateless as they don’t need to keep an open connection, so scaling them is far easier. Webhook providers can cater to much larger volumes of subscribers and scale in either direction to meet demand. 

Webhooks are also simpler for the consumer, with no need to manage connections and state information. This makes them especially useful for services that regularly publish updates to many different consumers. And if you’re tracking sales on an online marketplace store, or donations to a charity page with millions of donors, webhooks let you process these updates in real-time.

You may think that WebSockets are the best choice for a chatbot, as communication goes both ways. However, to be able to meet scaling demands, larger businesses should consider webhooks — especially if they handle large numbers of users in simultaneous chat sessions.

WebSockets Use Case

There are instances where two-way communication is required between a client and a server so that data can be shared in real-time. 

For example, consider building a web document editing service that allows multiple people to edit and update a document in real-time via their browsers. This would be a great use case for WebSockets. If two users have the same document open in their browser, both will be connected to the server via a WebSocket. When User A makes a change, it’s sent from the client to the server before being relayed back to User B, updating their browser and showing the edit. This exchange can continue, with both users submitting changes, the server processing them, and the changes being relayed back in real-time. 

Though it’s possible to achieve this real-time communication with webhooks, there would likely be latency issues with such a large number of API calls to send and receive updates. Using a WebSocket helps to eliminate latency and delays.

Conclusion

Webhooks and WebSockets are both great tools for real-time conversation analytics and real-time communication over the Internet. However, their different methods of communication make webhooks and WebSockets best suited to different uses. If you require one-way communication between two servers and scaling is important, you should use webhooks. If you need two-way communication between a client and server that are constantly exchanging data in real-time, you’ll find that WebSockets will better meet your needs.

If webhooks suit your needs best, just remember to take care when implementing them. A webhook is effectively a reverse API, so you should carefully consider what information is being exposed. Signing and encrypting payloads ensures that data can’t be intercepted and viewed by anyone other than the expected party. With your webhooks secured, you’ll be able to safely scale as needed, experiencing their benefits with the knowledge that your data is safe.

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Joshua Molina
Director of Content, Symbl.ai

Joshua is a former journalist and veteran tech writer. He currently leads content strategy at Symbl.ai.