Data protocol models used with IoT
- Request/Response model
- Often used in distributed system where the communication flow between servers and clients consists fo requests and responses for data. Examples include HTTP and CoAP (described in the “IoT data protocols at the application layer” section below)
- Publish/Subscribe model: A framework for message exchanges between publishers (hosts) and subscribers (clients) that are routed through a broker. Subscribers can sign up to a channel to receive notices through the broker when the publisher releases new messages. Examples: MQTT and AMQP (described in the “IoT data protocols at the application layer” section below).
IoT data protocols at the application layer
- HyperText Transfer Protocol / secure (HTTP/ HTTPs): HTTP and HTTPs are the most widely used information transfer protocols across the World Wide Web (WWW). The protocols define how information is formatted and transmitted.
- Machine-to-Machine (M2M) Communication Protocols
- A set of direct communications method for low power devices, machines and systems. There are three primary architectural and protocol groups in M2M electronic communications.
- Representational State Transfer (REST)
- communications amongst web accessible systems
- Service-oriented Architectures (SOA)
- data exchanges in industrial automation systems.
- Message Oriented Protocols
- asynchronous data transfers for distributed system
- Message Queue Telemetry Transport (MQTT)
- An IoT data-centric interaction protocol for M2M that uses a simple publish-subscribe model. MQTT supports Quality of Service (QoS), uses TCP for sending information, and utilizes Secure Socket Layer (SSL) and Transport Layer Security (TLS) for security. MQTT using binary format and 2-byte header sizes for efficient messaging. MQTT is supported by Google Cloud IoT Core for device to cloud communication
- Constrained Application Protocol (CoAP)
- A web transfer protocol for IoT constrained nodes and networks designed for M2M applications. CoAP is used for IoT applications like building automation and smart energy management. CoAP is very similar to HTTP: both are based on the REST model and both place resources on a server that is accessible to clients via a URL
- Advanced Message Queueing Protocol (AMQP)
- An open standard for messaging amongst applications in different organizations and/or platforms. Its purpose is to remove vendor lock-in for app communication. In addition to interoperability, AMQP also offers reliability and security.
- Extensible Messaging and Presence Protocol (XMPP)
- A decentralized, open stand for chat, messaging, video and voice calls, collaboration tools, and more. Built upon Jabber, XMPP offers a proven communication technology that is extensible, flexible, and diverse.
- Data Distribution Service (DDS)
- An API standard and middleware protocol from the Object Management group. Middleware exists in the OSI applications layer, between software and the operating system. DDS uses the publish-subscribe communications model. DDS is also data-centric, provides, low-latency data connectivity, and helps the device in an IoT ecosystem share data more efficiently. DDS is reliable, scalable, and provides control of QoS parameters, including bandwidth and resource limits.