All files / src/payload-stack/payload index.js

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/**
 * Represent a package of data to send over the network
 */
class Payload
{
  /**
   * @callback Payload~from
   * @param {string} event
   * @param {*} data
   */
  static from(event, data)
  {
    return new Payload(event, data)
  }
 
  /**
   * @param {string} event
   * @param {*} data
   */
  constructor(event, data)
  {
    this.event  = event
    this.data   = data
 
    Object.freeze(this)
  }
 
  /**
   * @returns {string} Stringified JSON
   */
  toStringifiedJson()
  {
    const
    event = this.event,
    data  = this.data
 
    return JSON.stringify({ event, data })
  }
 
  /**
   * Composes a binary package with a header and body
   * @returns {Buffer}
   */
  toBuffer()
  {
    const
    dto     = this.toStringifiedJson(),
    body    = Buffer.from(dto),
    header  = Buffer.alloc(Payload.HEADER_SIZE)
 
    header.writeInt32BE(body.length, 0)
 
    return Buffer.concat([header, body])
  }
}
 
/**
 * The byte size of the header
 * @const
 */
Payload.HEADER_SIZE = 4
 
module.exports = Object.freeze(Payload)