R/mqtt_topic_publish.R

In boralprophecy/rmqtt: MQTT Client for R

#' @title Publishes to mqtt topics
#'
#' @description The function \code{mqtt_topic_publish} publishes messages to mqtt topics
#'
#' @param topic character string, mqtt topic to publish to.
#'
#' @param message_to_send character string, message to send. Defaults to NULL.
#'
#' @param intern logical (not NA), indicates whether to capture the output as an R character vector. Defaults to FALSE.
#'
#' @param host  character string,  mqtt host to connect to. Defaults to localhost.
#'
#' @param port  integer, connect to the specified port. Default NULL denotes 1883 for plain MQTT or 8883 for MQTT
#'              over TLS.
#'
#' @param qos integer : 0 or 1 or 2, quality of service level to use for the message. Defaults to 0.
#'
#' @param enable.debugging logical (not NA), whether debug messages should be enabled. Default is FALSE.
#'
#' @param retain_message logical (not NA), whether whether message should be retained. Default is FALSE.
#'
#' @param send_null_message logical (not NA), whether to send a null (zero length) message. Default is FALSE.
#'
#' @param username  character string, Provide a username to be used for authenticating with the broker. Defaults
#'
#'                  to NA which denotes username not provided.
#'
#' @param password  character string, Provide a password to be used for authenticating with the broker. Using this
#'
#'                  argument without also specifying a username is invalid. Defaults to NA which denotes password not provided.
#'
#' @param clientid character string, id to use for this client. Defaults to NULL, means mosquitto_pub_ appended with
#'                 the process id of the client.
#'
#' @examples
#'
#' #...... publishes message to localhost ......
#'
#'\donttest{
#' mqtt_topic_publish( topic = 'magic/demo/note5', message_to_send = "Life is beautiful."  )
#' }
#'
#' #.... Stores output as R character vector. Turning it off, just prints the output to console
#' # when debugging is enabled ....
#'
#'\donttest{
#' mqtt_topic_publish( topic = 'magic/demo/note5', message_to_send = "Life is beautiful.", intern = T,
#' enable.debugging = T )
#' }
#'
#' #.... Sending message with username and password ....
#'
#'\donttest{
#' mqtt_topic_publish( topic = 'magic/demo/note5', message_to_send = "Life is beautiful.",
#' username = 'Soumya', password = 'Boral' )
#' }
#'
#' @export


mqtt_topic_publish = function( topic, message_to_send = NULL, intern = F, host = 'localhost', port = NULL, qos = 0,

                               enable.debugging = F, retain_message = F, send_null_message = F, username = NA,

                               password = NA, clientid = NULL ){

  #..... Arguments check ......

  if( !is.character( topic ) ){ stop( 'topic must be character string.' ) }

  if( ! send_null_message && !is.character( message_to_send ) ){ stop( 'message must be character string.' ) }

  if( send_null_message && is.character( message_to_send ) ){ stop( 'Either null message or a message string can be sent at once.' ) }

  if( is.na( intern ) || !is.logical( intern ) ){ stop( 'intern must be logical (not NA).' ) }

  if( !is.character( host ) ){ stop( 'host must be character string.' ) }

  if( !is.null( port ) && round( port ) != port ){ stop( 'port must be either NULL or integer.' ) }

  if( round( qos ) != qos || !( qos %in% c( 0, 1, 2 ) ) ){ stop( 'qos must be an integer among 0, 1 or 2.' ) }

  if( is.na( enable.debugging ) || !is.logical( enable.debugging ) ){ stop( 'enable.debugging must be logical (not NA).' ) }

  if( is.na( retain_message ) || !is.logical( retain_message ) ){ stop( 'retain_message must be logical (not NA).' ) }

  if( is.na( send_null_message ) || !is.logical( send_null_message ) ){ stop( 'send_null_message must be logical (not NA).' ) }

  if( !is.na( username ) && !is.character( username ) ){ stop( 'username must be character string or NA which means username not provided.' ) }

  if( !is.na( password ) && !is.character( password ) ){ stop( 'password must be character string or NA which means password not provided.' ) }

  if( is.character( username ) && grepl( ' ', username ) ){ stop( 'username cannot contain spaces.' ) }

  if( is.character( password ) && grepl( ' ', password ) ){ stop( 'password cannot contain spaces.' ) }

  if( is.na( username ) && is.character( password ) ){ warning( 'Not using password since username not set.' ) }

  if( !is.null( clientid ) && !is.character( clientid ) ){ stop( 'clientid must be character string.' ) }



  mqtt_pub_base = ifelse( host == 'localhost', "mosquitto_pub", paste0( "mosquitto_pub -h ", host ) )    #.... adding host

  if( !is.null( port ) ){ mqtt_pub_base = paste0( mqtt_pub_base, ' -p ', port ) }    #.... adding port

  if( enable.debugging ){ mqtt_pub_base = paste0( mqtt_pub_base, ' -d ' ) }    #...... enabling debug messages

  if( retain_message ){ mqtt_pub_base = paste0( mqtt_pub_base, ' -r ' ) }    #...... enabling debug messages

  if( !is.na( username ) ){    #..... adding username

    mqtt_pub_base = paste0( mqtt_pub_base, ' -u ', username )

    if( !is.na( password ) ){ mqtt_pub_base = paste0( mqtt_pub_base, ' -P ', password ) }    #...... adding password

  }

  if( send_null_message ){

    mqtt_pub_base = paste0( mqtt_pub_base, ' -n ' )    #..... sending null message

  } else{

    mqtt_pub_base = paste0( mqtt_pub_base, ' -m "', message_to_send, '"' )    #..... adding message ... quotes are necessary in case message contains space

  }

  if( !is.null( clientid ) ){ mqtt_pub_base = paste0( mqtt_pub_base, ' -i "', clientid, '"' ) }    #.... adding clientid

  mqtt_pub_base = paste0( mqtt_pub_base, ' -q ', qos )     #..... adding qos

  mqtt_pub_command = paste0( mqtt_pub_base, ' -t "', topic, '"' )     #..... adding topic ... quotes are necessary in case topic contains space

  system( mqtt_pub_command, intern = intern )

}