mqtt_client_simple connection issues

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There is an issue when user try to use mqtt_client_simple:

When user wants to connect to the remove mqtt brocker, he will start mqtt_client_simple.
NOTE: mqtt server is running on a remove machine.

    Props=[{host,"hostName"},{port,1883},{client_id,<<"test_id1">>}].
    mqtt_client_simple:connect(Props).

Ant then he will receive an error message:

** exception exit: {noproc,
                    {gen_server,call,
                     [mqtt_client_sup,
                      {start_child,
                       {<<"test_id1">>,
                        {mqtt_client,start_link,
                         [[{handler,mqtt_client_simple},
                           {handler_state,
                            {mqtt_client_simple,<<"test_id1">>,undefined}},
                           {host,"hostName"},
                           {port,1883},
                           {client_id,<<"test_id1">>}]]},
                        transient,brutal_kill,worker,dynamic}},
                      infinity]}}
     in function  gen_server:call/3 (gen_server.erl, line 188)
     in call from mqtt_client_sup:connect/2 (src/mqtt_client_sup.erl, line 45)`

The reason is that mqtt_client:connect method expected that mqtt_client_sup is started.

There are few options how this could be fixed.

• Explain this in documentation - simplest and less convenient for the user
• Automatically start mqtt_clinet_sup when required - downside that it would not be part of the user's supervision tree
• Implement matt_client_simple as a separate application - probably the best option.

[considerate]

I have thought about this for a while now.

I agree that it would be best to extract mqtt_client_simple as a separate project. Maybe we should call it fubar_client. This project would then include fubar as a dependency with rebar.

I haven't looked at the code for a while now but I think it'd be possible to do that without starting fubar as a server.

The modules to extract would be:

• mqtt_client_sup
• mqtt_client_simple

When starting the fubar_client we would also then spin up a supervisor (client_sup).

What are your thoughts?