Parameters:

• topic (required): Address for the message, e.g. myAddonRootVar/function1/myTopic/. The same topic must be used when retrieving the message.
• payload (required): The message to send, e.g. "test message".
• token (optional): Key string. If provided, the exact same string must be supplied when retrieving the message.
• lifetime (optional): How long the message is available, in seconds. Default 8 hours, maximum 7 days (adjustable for dedicated installations).