IoT Communication APIs

Generally we used Two APIs For IoT Communication. These IoT Communication APIs are:

• REST-based Communication APIs
• WebSocket-based Communication APIs

REST-based Communication APIs

Representational state transfer (REST) is a set of architectural principles by which you can design Web services and Web APIs that focus on systems’ resources and how resource states are addressed and transferred. REST APIs follow the request-response communication model. The REST architectural constraints apply to the components, connectors, and data elements within a distributed hypermedia system. The REST architectural constraints are as follows:

• Client-server: The principle behind the client-server constraint is the separation of concerns. For example, clients should not be concerned with the storage of data, which is a concern of the server. Similarly, the server should not be concerned about the user interface, which is a concern of the client. Separation allows clients and servers to be independently developed and updated.
• Stateless: Each request from the client to the server must contain all the information necessary to understand the request and cannot take advantage of any stored context on the server. The session state is kept entirely on the client.
• Cache-able: Cache constraints require that the data within a response to a request be implicitly or explicitly labeled as cacheable or non-cacheable. If a response is cacheable, then a client cache is given the right to reuse that response data for later, equivalent requests. Caching can partially or completely eliminate some instructions and improve efficiency and scalability.
• Layered system: Layered system constraints constrain the behavior of components such that each component cannot see beyond the immediate layer with which they are interacting. For example, the client cannot tell whether it is connected directly to the end server or to an intermediary along the way. System scalability can be improved by allowing intermediaries to respond to requests instead of the end server, without the client having to do anything different.
• Uniform interface: Uniform interface constraints require that the method of communication between client and server must be uniform. Resources are identified in the requests (by URIs in web-based systems) and are themselves separate from the representations of the resource’s data returned to the client. When a client holds a representation of resources, it has all the information required to update or delete the resource (provided the client has required permissions). Each message includes enough information to describe how to process the message.
• Code on demand (optional): Servers can provide executable code or scripts for clients to execute in their context. This constraint is the only one that is optional.

A RESTful web service is a “Web API” implemented using HTTP and REST principles. REST is the most popular IoT Communication API.

HTTP Methods

WebSocket-based Communication API

WebSocket APIs allow bi-directional, full-duplex communication between clients and servers. WebSocket APIs follow the exclusive pair communication model. Unlike the request-response model such as REST, the WebSocket APIs allow full-duplex communication and do not require a new connection to be set up for each message to be sent.

WebSocket communication begins with a connection setup request sent by the client to the server. The request (called WebSocket handshake) is sent over HTTP, and the server interprets it as an upgrade request. If the server supports the WebSocket protocol, the server responds with a WebSocket handshake response. After the connection setup, the client and server can send data/messages to each other in full-duplex mode.

WebSocket APIs reduce network traffic and latency as there is no overhead for connection setup and termination requests for each message. WebSocket is suitable for IoT applications that have low latency or high throughput requirements.

In addition to low latency, WebSocket APIs are ideal for real-time IoT systems that require frequent data exchange, such as:

• Remote Monitoring Systems that constantly stream sensor data
• Smart Home Automation for instant device control
• IoT-based Chat Applications that require seamless message flow

So WebSocket is the most suitable IoT Communication API for IoT systems that demand real-time data exchange, low latency, and improved efficiency.