Feature request - Add some form of identification to dynamic security responses

[kozeljko]

We are integrating mosquitto as our MQTT broker and are currently working on using using the dynamic security control topic ($CONTROL/dynamic-security/v1) for configuring users/groups/roles/acls.

The idea is to send a message and subscribe to the response topic ($CONTROL/dynamic-security/v1) for the result. What worries me is that there are no guarantees that I will receive the exact response for my request. For example: If client1 sends request1("createClient") and client2 sends request2("createClient") they might both receive response1 as the answer, while response2 is ignored. We are currently mitigating this issue by having a single client for the configuration, but there's always a chance that a new client connects.

I'm not sure if this is a good approach, but would it be possible to add some kinda of id field to the request payloads sent to the dynamic security topic? These ids would then be matched to an id field in the response payload.

[ralight]

You can add a correlationData field like shown below - I see that isn't explained in the documentation though.

I'm also considering restricting replies to the client that sent the request, what do you think?

{
    "commands":[
        {
            "command": "setDefaultACLAccess",
            "acls":[
                { "acltype": "publishClientSend", "allow": false },
                { "acltype": "publishClientReceive", "allow": true },
                { "acltype": "subscribe", "allow": false },
                { "acltype": "unsubscribe", "allow": true }
            ],
            "correlationData": "6143ce34-a184-43cb-8d5e-a4aa39e7a185"
        }
    ]
}