The rapid growth of the internet has led to an increase in demand for real-time technology, enhancing communication between clients and servers. WebSockets have grown in popularity and are now one of the most popular methods for enabling real-time communication. However, WebSockets may not always be the best option, as the choice of technology depends on the specific use case. There are many alternative options available that might be better suited for particular situations.
A WebSocket is a protocol that provides full-duplex communication and bi-directional communication channels between clients and servers over the web. It allows real-time data transmission between the client side and the client server without reconnecting to the server. Unlike a traditional HTTP protocol, WebSockets enable the client and server to initiate communication and send data anytime, making them ideal for real-time data transmission.
Almost every time developers think about real-time communication, we use WebSockets. Why is this the case? Are they the only/best choice to achieve real-time transmission, no matter the use case?
To put it simply, WebSockets provide advanced functionalities but, depending on the use case, can have many drawbacks that can quickly increase a project's complexity. To solve this, let's consider why developers would pick a WebSocket alternative.
Performance: WebSockets are most known for their advanced functionality but sometimes can pose an overkill solution and lead to poor performance. It is essential to consider the use case when deciding to use WebSockets. For example, there are better solutions than WebSockets if you need a high concurrency of connections. WebSocket connections have to remain alive between the client and the server leading to increased load on the server and underlying infrastructure as you scale.
Interoperability: WebSockets are supported by all modern web browsers/networks. By chance, if the software is being used in a legacy browser or network, it is essential to consider if WebSockets has support in that legacy system. Additionally, networks and proxies sometimes block WebSocket connections altogether, so where you use the software is another factor to consider.
Security: WebSockets are not secure as some alternatives and have vulnerabilities that malicious actors can exploit. Some reasons WebSockets are considered less secure than other protocols include cross-site WebSocket hijacking and origin spoofing.
Long polling is an approach where the client sends an HTTP/HTTPS request to the server, but instead of receiving an instant response from the server, it entails maintaining the HTTP connection. Maintaining the HTTP connection enables the server to reply later when data becomes available, or the timeout threshold has been reached. After receiving the response, the client will immediately send the subsequent request.
Long polling achieves real-time communication without the bi-directional communication channels that WebSockets provide. The core difference is instead of maintaining a persistent connection as with WebSockets, the client will send multiple requests to re-establish the connection with the server.
MQTT is a lightweight, publish-subscribe, machine-to-machine network protocol designed for remote locations with devices that have limited network bandwidth. Smart sensors, wearables, and other IoT devices typically need to use such a protocol due to their resource constraints. While WebSockets can be used for various applications, MQTT is explicitly designed for machine-to-machine communication, which is why it’s considered an alternative under these use cases. MQTT provides features like low overhead, efficient message delivery, and support for offline operation.
WebTransport is a new web communication protocol that provides a low-latency and high-throughput connection between a client and a server. It was created to address some of the limitations of traditional protocols, such as WebSockets, and provide a modern alternative that can better handle the demands of today’s web applications.
While WebSockets typically start as an HTTP/1.1 Upgrade request, WebTransport supports multiple protocols, including HTTP/2, HTTP/3, and QUIC, and is a UDP-based transport. Additionally, WebTransport supports sending data reliably via its streams API and unreliably via its datagrams API. With this new technology, how does it compare to WebSockets and what are the advantages of switching to WebTransport protocol?
Advanced Functionality: A challenge with WebSockets is that it can be difficult to send different types of data, such as an image and text, over a single connection. The issue arises because the data is divided into smaller units, known as packets, for transmission over a TCP connection. When dividing the data into packets, there is no way to distinguish between the plain text and the encoded image contained within the data. To resolve this, WebSockets often need to make two separate connections between the server and client, one for pictures and one for text. However, WebTransport provides a solution by supporting multiple streams, known as multiplexing. By supporting multiple streams, developers can send different types of data over one connection, reducing the overhead of establishing and maintaining numerous connections. This becomes essential when the server needs to support many clients. Multiple connections per client, as in WebSockets, can lead to complexities when the server starts to scale.
Improved Performance: WebTransport is a UDP-based transport protocol more performant than TCP-based protocols like WebSockets. Due to it being UDP based, there is no error correction or retransmission. Error correction refers to detecting and correcting an error that may occur in the transmitted data. Retransmission refers to the processing of resending lost or corrupted data packets over the network. Due to not having the overhead of correction and retransmission, this lowers the latency of WebTransport. WebTransport also offers a WebTransportCongestionControl configuration which can optimize the throughput and latency of requests. Secondly, Establishing a new connection with WebTransport over QUIC handshake is typically faster than TCP over TLS.
Reliability: The lack of error correction and retransmission might make a developer think WebTransport is less reliable than WebSockets. That is not the case; WebTransport, by design, provides more reliability than WebSockets, especially in scenarios with high-bandwidth communication and challenging network conditions. WebTransport provides a streams API for reliable unidirectional (WebTransportReceiveStreams) or bidirectional two-way (WebTransportBidirectionalStream) data transfer. This API endpoint offers configurations such as WebTransportReliabilityMode, which can allow the connection to have a TCP fallback in scenarios where reliable data transfer is essential.
Security: WebTransport offers a more secure protocol than WebSockets. It provides end-to-end encryption by default, which ensures that the data between the client and server cannot be intercepted or modified in transit. One of these security features is the use of an “Origin” header, which provides a way for the server to verify that the requests are coming from a trusted source. This helps prevent cross-site request forgery (CSRF) attacks.
Server-Sent Events (SSE) is a server push technology that allows a server to push data to a client over a single HTTP connection. SSE is a simple, efficient protocol for sending real-time updates to a web page or application, making it well-suited for specific use cases. Unlike traditional HTTP requests, which close the connection after a single response, SSE opens a long-lived connection between the server and the client, allowing the server to send multiple updates over the same connection. Compared to WebSockets’s bidirectional connections, Server-Sent Events are only unidirectional. The client only has to initiate the connection and close it. However, the limited feature set of Server-Sent Events makes it easier to implement and debug. Server-Sent Events was the start of the EventSource API, which makes it easy to implement in web browsers.
WebSocket protocol and its alternatives, such as WebTransport, are all valuable solutions to handling real-time communications. However, no matter what solution is selected, time will be wasted in implementing the underlying infrastructure and complexities when scaling. For example, when using particular technologies such as Socket.io to create a WebSocket server, developers will still have to take care of dynamically spawning servers around the world behind a load balancer to manage the utilization of each web server.
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