Command Handler


The Sming CommandHandler implementation adds the possibility to handle system and application commands over a variety of input media.

The CLI provides a framework in which basic system commands can be extended and application specific commands created.

Currently implemented are: - Serial - Telnet Server - Websocket Server


The implementation makes use of a global object CommandHandler, which at the start is just a skeleton without any command active.

System commands can be activated using: - Serial.commandProcessing(true) - telnetServer.enableCommand(true) - websockerServer.commandProcessing(true, "command")

The additional parameter for websocket is used to allow multiple connections on one websocket server instance, both with or without command proceesing.

When the websocket open request has query parameter "command=true" command processing is enabled.


The usage of CommandProcessor is the same for all implementations, except for specific requirements. CommandProcesor options implemented are: - Verbose -> sets display of welcome message - Prompt -> set prompt string - EOL -> set end of line character - welcome message -> set the welcome message

System Commands

The base CommandHandler has the following sysytem commands implemented: - help, Displays all available commands - status, Displays System Information - echo, Displays command entered - debugon, Set Serial debug on - debugoff, Set Serial debug off - command, Usage verbose/silent/prompt for command options

Application options

Applications (and Sming Core functionality) can add commands to the CommandProcesor using a construct like

    "Displays System Information",
    commandFunctionDelegate(&CommandHandler::procesStatusCommand, this)

The added command will then be available over every opened command channel.

Example usage

The capabilities of CommandHandler are shown in the example CommandProcessing_Debug.

The example will create an application which shows CommandProcessing for Telnet, Websocket and Serial.

  • to test Telnet, open telnet client and connect on port 23 to the ESP ip
  • to test the Websocket, open a web browser with the ESP
  • to test Serial use your “Serial program” and make sure “local echo” is activated

For all implementations type “help” to show the available Commands

The possibilities of extending commands with the application are shown in: - the class ExampleCommand - the functions startExampleApplicationCommand() and processApplicationCommands()