I have read something about "messaging system" using the MQTT protocol. But i was always reading about the constellation:
using Android as a MQTT-Client and a MQTT-Server which is not installed on a Android smartphone oder tablet (but as a standalone server).
Is it possible to use one Android-Tablet as a MQTT-Server and some other Android-Tablets (for example 5 Tablets) as MQTT-Clients??
And if this is possible, is it possible to use the one Android-Tablet which is a MQTT-Server, also as a MQTT-Client?
The communication between the Android-MQTT-Server-Tablet and the other tablets as MQTT-Client, should work over an WIFI-Router / WIFI-Access-Point.
Thank you in advance for helping.
It is possible to use tablets as mqtt brokers (server) and mqtt clients. You'll have to use a client library on all tablets and a broker on one of them.
Here is pure java broker I have adapted to work on Android: https://github.com/interaktionsbyran/moquette Feel free to try it out!
It's perfectly possible.
The hard bit would be working out which tablet would become the broker. One approach would be to use avahi (mDNS) to try and discover a broker, if none are found then set one up and advertise it via avahi.
As for actually finding a broker that will run on Android that would be anther challenge. I'm not aware of a public pure Java broker available, but you may be able to get mosquitto to compile as a native (arm) Android app, but you would need to write a service wrapper for it.
