STOMP
Like stated in https://stomp.github.io/ STOMP is the Simple (or Streaming) Text Orientated Messaging Protocol. It provides an interoperable wire format so that STOMP clients can communicate with any STOMP message broker to provide easy and widespread messaging interoperability among many languages, platforms and brokers.
Telnet can be used to login and interact to any STOMP broker.
STOMP providers: