Communication Models in IoT

There are 4 types of communication model in IoT.-

1. Request-Response Model

In this model, a client sends a request to a server. The server receives it, processes it, fetches the required data, and sends back a response. It is a stateless model — each request-response pair is independent.

Real-life example: When you open Google.com in a browser, your browser (client) sends a request to Google's server. The server fetches the search page and sends it back. Every new search is a fresh, independent request.

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2. Publish-Subscribe Model

Here, there are three roles: publishers, brokers, and consumers (subscribers). The publisher sends data to topics managed by the broker. Subscribers register their interest in specific topics. The broker then forwards data to all matching subscribers. Importantly, the publisher does not know who the subscribers are.

Real-life example: Think of a YouTube channel. The channel owner (publisher) uploads a video. YouTube's platform (broker) manages subscriptions. Everyone who subscribed (subscribers) gets notified automatically — the creator doesn't personally notify each subscriber.

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3. Push-Pull Model

Data producers push data into queues. Consumers then pull data from those queues whenever they are ready. Queues act as a buffer, so if the producer is faster than the consumer, data is held in the queue without being lost.

Real-life example: Think of an e-commerce warehouse. Orders (data) keep coming in and go into a processing queue. Workers (consumers) pick up orders from the queue one by one at their own pace. If 1,000 orders arrive suddenly, they wait in the queue instead of crashing the system.

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4. Exclusive Pair Model

This is a bidirectional, fully duplex model where a persistent connection is maintained between client and server. Both sides can send messages simultaneously. The connection stays open until the client explicitly closes it. This is a stateful model — the server knows all active connections.

Real-life example: A WhatsApp or phone call is a perfect example. Once the call connects, both people can speak and listen at the same time. The connection persists throughout the call, and it only ends when one person hangs up.