redesign MQTT functionality

[bertt]

drawbacks current MQTT solution:

• need non-standard GOST prefix when publishing data using MQTT

• supports publish/subscribe only on Observations

Need to have a new design fixing those drawbacks (so remove prefix and support publish/subscribe on all entities) .

[bertt]

maybe usefull? https://github.com/tmc/pqstream

[tebben]

Tried VolantMQ a few months back which looks promising but missing some functionality for us to be useful, I created an issue back then: VolantMQ/volantmq#60

Also found this in the issue list with almost the same question: VolantMQ/volantmq#85 which is from 8 days ago

Other VolantMQ remarks:

• Currently errors when running on Windows
• SSL support soon

Options:

1. fork VolantMQ and create simple workaround
2. help with VolantMQ API system
3. wait for updates and focus on other issues/features/dashboard

@bertt An other question is how do we want to implement MQTT, should GOST server be able to act as MQTT broker or do we want a different application/server for it? Will we run into problems such as load balancing/stateless server when running the MQTT broker from GOST server?

[bertt]

q1: lets wait for some more updates VolantMQ
q2: lets frst try to combine GOST with MQTT, maybe later separate

[bertt]

it would be nice for demo purpose to have current location of things as mqtt stream as a start

[farshidtz]

It would be very nice if at least the GOST prefix is configurable, otherwise you can't have two servers using the same broker.

[bertt]

@farshidtz I've created a new issue for this see #150

[bertt]

NB: MQTT subscribe Location updates is added in 04d19be

[bertt]

another Go MQTT broker https://github.com/fhmq/hmq

offers 'Kafka Bridge Support - Action Deliver - Regexp Deliver' might be interesting option KPN DSH.