Comparing Diffusion With Socket.IO
December 12, 2025 | DiffusionData
Introduction
Socket.IO is an event-driven library for real-time web applications, allowing bi-directional communication between web clients and servers. It supports multiple communication protocols, including WebSockets.
Diffusion specializes in real-time data management and distribution across a network. Diffusion delivers data under all network conditions with its reliable session reconnection. Diffusion’s delta streaming provides efficient transmission of data thus enabling it to scale well to handle many subscribers.
Socket.IO and Diffusion are both used for applications that require high-frequency updates, like chat applications, gaming, or live data feeds. As you will see Diffusion offers many more features than Socket.IO.
Server-Client Communication
Socket.IO
The Socket.IO server communicates directly with its clients as shown below.
Socket.IO Server – Client Communication
The main server implementation is for Node.js though there are other implementations.
The code below shows how a Socket.IO server (run using Node.js) sends messages to connected clients in a browser.
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The Node.js web framework Express is used to initialize the application before creating the HTTP server ‘server’ with the server listening on port 3000. A new instance of socket.io is initialized (by passing the server object) and then listens on the ‘connection’ event. When it receives this from a client it will send a welcome message to the client.
const app = express(); const server = createServer(app); const io = new Server(server); server.listen(3000, () => { console.log('server running at http://localhost:3000'); }); io.on('connection', (socket) => { socket.emit('session connection', { message: 'Welcome!', id: socket.id }); });
2. The code below simulates sending the current traded price of Apple stock to all connected clients every second.
function sendPrice() { var stock_price = apple_base_price + Math.random(); io.emit('price', { price: stock_price.toFixed(2) }); } setInterval(sendPrice, 1000);
3. The client browser application creates a socket.io connection then watches for events to be emitted by the server as shown below. The callbacks that run when an event is received add a message to a list in the DOM. When the client first connects to the server it will receive a ‘Welcome’ message which it displays. Subsequent ‘price’ events received will display the stock price in the list.
<head> <script src='/socket.io/socket.io.js'></script> <script> var socket = io(); socket.on('session connection', function(data) { addMessage(data.message); addMessage('Apple is currently trading at:'); }); socket.on('price', function(data) { addMessage(data.price); }); function addMessage(message) { // add message here } </script> </head> <body> <ul id='messages'></ul> </body>
Diffusion
The Diffusion control client (publisher) communicates with its clients (subscribers) as shown below.
Diffusion Server – Client Communication
The code below shows how the publisher sends messages to subscribers.
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The publisher establishes a session with the Diffusion server.
const session = await connect({ host: 'localhost', port: 8080, principal: 'admin', credentials: 'password' }); console.log(`Connected to Diffusion via session ${session.sessionId}`);
2. The publisher creates a topic, in this case a JSON topic, on a topic path e.g. ‘Stock’ then sets it with data.
session.topics.add(topicPath, topics.TopicType.JSON); session.topicUpdate.set(topicPath, datatypes.json(), jsonValue);
3. The subscriber establishes a session with the Diffusion server as above.
4. The subscriber creates a value stream to receive data and subscribes to the same topic path.
5. The value stream receives data from the server as shown below.
const valueStream = { value: (topic, spec, value) => { console.log(`Update for topic ${topic}: ${JSON.stringify(value.get())}`); }, } const subscription = session.addStream(topicPath, datatypes.json()); subscription.on(valueStream); session.select(topicPath);
Point of Comparison
| Socket.IO | Diffusion | |
|---|---|---|
| Solution Type | Open source real-time library | On-prem and cloud-based solution |
| Scalability | Scale with the Cluster adapter and other adapters | Use Diffusion Servers in an edge-layer |
| Guaranteed message ordering | Yes | Yes |
| Reconnections with continuity | Provides automatic reconnections, but some messages may never get delivered upon reconnection. | Provides automatic reconnections, but some messages may never get delivered upon reconnection. However the Diffusion client will be updated with the most recent value for each topic that it is subscribed to. |
| Protocols |
WebSockets HTTP Long polling WebTransport |
WebSockets HTTP Long polling MQTT |
| Multiplexing | Yes | Yes |
| Integrations | Socket.IO provides adapters for Redis, MongoDB, Postgres, and Cloud providers. Socket.IO can integrate with RabbitMQ and other AMQP services using its AMQP adapter. |
Diffusion is able to integrate with Kafka, Redis and Excel as well as message brokers that support AMQP 1.0. Diffusion offers REST API and can also connect to IoT devices through the MQTT protocol. |
| Message history/persistence | No | Yes |
| Broadcast (1:many messaging) | Yes | Yes |
| Streaming | Yes | Yes |
| SDKs | .NET, Java, JavaScript, Python, Rust, Golang, C++, Swift | .NET, Java, JavaScript, TypeScript, Python, C, iOS |
| Delta Compression | No | Yes |
| Data Types | Primitive types, JSON, binary | Primitive types, JSON, binary, Time Series |
Benefits of Diffusion
1. Topic Views – Low-code Topic Views can easily transform and map incoming data.
- Topic Views can aggregate multiple incoming values into one topic, expand a single incoming data point and generate subtopics, as well as tailor data for delivery.
- Copy all or part of the topic tree on one server to another with Remote Topic Views. Ideal for distributing data across a geographically dispersed user base.
- Topic Views can be used to create a delayed feed and are ideal for creating lower-value versions of time-sensitive data.
- Socket.IO does not offer Topic View functionality.
2. Diffusion updates for any given topic are guaranteed to be in order (but updates for different topics can be received in any order).
3. Diffusion is designed to efficiently distribute data by sending only the data that is required to subscribers, rather than sending everything. It categorizes and splits data into a hierarchical topic tree. Comparatively Socket.IO would need additional logic to control where data was sent.
4. Diffusion provides message history through its Time Series Topics feature – This allows you to store and access a historical sequence of events, which is useful for applications that require tracking changes over time. It stores a time-stamped event within a single topic and streams events as they happen or queries to retrieve part of a series. Socket.IO has no mechanism to provide message history.
5. Diffusion supports delta compression – The platform includes a delta-streaming protocol that intelligently distinguishes between old, updated and new data, only sending recent, relevant, information to clients instead of the entire topic content. This enables up to 90% reduction in server and bandwidth requirements by avoiding the need to send data that isn’t changing from one update to the next. Socket.IO does not support deltas.
6. Diffusion provides pre-built adapters such as Kafka, REST, Redis and CDC (Change Data Capture) and gives you the ability to create your own.
7. Diffusion can integrate with RabbitMQ, Solace and ActiveMQ that support the AMQP 1.0 protocol.
8. Diffusion includes the MQTT protocol that enables direct connection to IoT devices using MQTT 5.0. Socket.IO does not directly support MQTT.
Summary
Diffusion offers many more features than Socket.IO:
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Diffusion has support for message history and delta compression.
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Diffusion offers REST API along with the MQTT protocol to connect to IoT devices.
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Diffusion’s Topic Views allow for easy transformation and mapping of incoming data.
For more information see our site.
Disclaimer: This comparison was created based on documentation and resources freely available online about Socket.IO. The content was last updated on 27 Nov 2025. Be sure to double-check everything before you make any decisions. If you do find anything incorrect or out of date, then please let us know.
