Ably vs WebSockets

WebSockets are a communication protocol and browser API that enables two-way realtime communication between apps (normally web apps).

To accomplish this, they establish a persistent connection between client and server, allowing them to exchange data in both directions without requiring explicit requests and responses.

Once the browser establishes a connection, apps can send messages at any time, and the other party receives them immediately, making them ideal for situations where two-way communication is required, such as chat or multiplayer collaboration. Additionally, WebSockets are well-suited to apps needing realtime updates like live sports scores, location tracking, charts, or stock tickers.

The WebSocket API the browser provides is remarkably small and simple to use. That said, there is usually more work to implement essential features like authentication, connection state recovery, and a heartbeat.

Ably is a realtime experience platform that enables two-way communication between apps.

The core idea is that apps publish messages to named logical channels (topics) that other devices can subscribe to. 

var ably = new Ably.Realtime('secret-key');
var channel = ably.channels.get('bitcoin-price');

//Publish a message to the bitcoin-price channel
channel.publish('update', '10000');

// Subscribe to a message (imagine this is running in a separate app)
channel.subscribe('update', function(message) {
  alert(message.data);
});

These messages traverse through the Ably platform in realtime before popping out on the client at the other end.

Ably's platform in a digram showing use cases, features, and integrations.

Under the hood, Ably supports client connections over multiple transports, however Ably’s preferred transport is the WebSocket protocol due to its portability and performance. 

Because Ably uses WebSockets under the hood, anything you can accomplish with WebSockets, you can achieve with Ably -  except, because Ably is a complete solution, you get additional features and capabilities out of the box like pub/sub, message history, connection state recovery, presence, and notifications. In other words, everything you need for production from day one.

WebSockets are a protocol that enables two-way realtime communication between web apps. By comparison, Ably is a service that provides an abstraction layer on top of WebSockets, with features like presence and authentication provided by default to make it easier to add realtime capabilities to your application.

The WebSocket browser API is fairly low-level, meaning it’s flexible if you want to implement your own custom communication protocol. At the same time, it leaves a fair amount of work for the developer compared to an Ably SDK. For example, detecting disconnections, recovering from disconnections on spotty networks, and resuming missed messages.

The decision to use Ably or roll your own WebSocket implementation depends on a couple of factors - first, the specifics of your situation. 

If you require fine-grain control over the WebSocket implementation, using WebSockets directly allows you to design your own architecture and protocol.  By comparison, Ably comes with a ready-made architecture based on the pub/sub pattern. Although this is an inherently flexible pattern, it might not be exactly what you want. 

Another aspect to consider is the work required to host and dynamically scale WebSockets in production. The fact that WebSockets uses a continuous connection introduces unique challenges around reliability, scale, and data integrity. What’s more, when users start connecting from around the globe expecting realtime updates, you must make provisions to ensure the lowest possible latency. If you don’t, your app could become slow and difficult to use, causing users to become dissatisfied with the overall experience. 

With Ably, developers can build realtime capabilities without needing to manage things like scaling, latency, data integrity, and network outages because the infrastructure part is all managed for you.

To help you decide which is best for your situation, we put together this comparison table: 

In summary, WebSockets are a lower-level protocol that is flexible but requires additional work on top.  Ably builds on WebSockets to provide a robust infrastructure, improved developer experience, and value-added features. 

WebSockets has two parts - the protocol and the WebSocket browser API. Although it might not take much time to implement a simple WebSocket app, building a solution you can depend on in production requires a solid understanding of how the WebSocket protocol works, the limitations of the browser API (and how to overcome them) - plus how to scale WebSockets. There are many tutorials out there, and we ourselves have one on getting started with JavaScript.

If you don’t feel the advantages of using WebSockets directly outweigh the benefits provided by a platform like Ably, a good place to start is by creating a free Ably account. You’ll be prompted to enter a bit of information about your technology stack and then guided to quick start guides and example apps tailored to you. Alternatively, feel free to peruse the documentation or read more about how the Ably platform guarantees the highest percentile of uptime and lowest latency.