cpp_example_template: Unique client_id for each agent

[vincentraymond-ua]

Currently, the example C++ agent template uses a hard-coded value for the mqtt::async_client client_id:

tomcat/exe/cpp_agent_template/Agent.cpp

Line 20 in a1ef93c

this->mqtt_client = make_shared<mqtt::async_client>(address, "agent");

The MQTT standard requires that client_ids be unique, otherwise it will disconnect the old client for the new one.

Perhaps we could introduce an agent_name variable and base the client_id off of that?

[adarshp]

@vincentraymond-ua - Thanks for catching that!

Eventually we should make this (and the heartbeat period) settable using a config file. I don't have the bandwidth to implement this myself in the near future, but will keep this in mind as an issue to be addressed before we deploy an agent based on this template to Study 4.

[adarshp]

@ualiangzhang - eventually when you get around to creating a C++ component that plugs into the message bus, please base it off of this template.

As a corollary, please also implement JSON config file parsing for things like client_id, heartbeat interval, etc. using Boost.JSON.

We can also discuss this at our 1-on-1 meetings.

[ualiangzhang]

@adarshp Thanks for letting me know! We can discuss this at our meeting next week.