How do you set semantics for a message transfer model?

To define the semantics of message passing models in Node.js, it is common to use a clear definition of message structures and their types. This can be done using schemas in JSON Schema format, TypeScript interfaces, or validation libraries such as Joi or Yup.

For example, if you have a messaging system, you can describe message types (e.g., request, response, event) and required fields to ensure all communication participants understand the data format.

An example using Joi:

const Joi = require('joi');

const messageSchema = Joi.object({
  type: Joi.string().valid('request', 'response', 'event').required(),
  payload: Joi.object().required(),
  timestamp: Joi.date().required()
});

function validateMessage(message) {
  const { error } = messageSchema.validate(message);
  if (error) {
    throw new Error(`Invalid message format: ${error.message}`);
  }
}

This approach helps define clear semantics and structure of messages, facilitating their processing and integration between services.