Reference a group of gateways through which a device can send messages

Since https://github.com/eclipse/hono/issues/926 it is possible to configure multiple gateways for a specific device. However, in some cases a group of devices are located on the same spot and can communicate through the same group of gateways. Therefore it would be useful to reference the groupid (of gateways) instead of specifying the same list over and over for each device. By doing this, a change in the group is automatically persisted to all devices. Ultimately we could have group of groups. When certain devices are allowed to roam between different groups of gateways. Currently we have some kind of this:

{
    "device-id": 4711,
    "via" : 
        [
            "gw-1",
            "gw-2",
            "gw-3"
        ]
}
{
    "device-id": 4712,
    "via" : 
        [
            "gw-1",
            "gw-2",
            "gw-3"
        ]
}

This might become:

{
    "device-id": 4711,
    "via" : 
        [
            "gw-group1"
        ]
}


{
    "device-id": 4712,
    "via" : 
        [
            "gw-group1"
        ]
}

{
    "gateway-group-id": "gw-group1",
    "gateways": [
        "gw-1"
    ]
    "gateway-groups": [
        "gw-group2"
    ]
}

{
    "gateway-group-id": "gw-group2",
    "gateways": [
        "gw-2",
        "gw-3"
    ]
    "gateway-groups": [
    ]
}

[BobClaerhout]

@sophokles73 of course it is already an improvement when we can define a gateway group and refer to it instead of the current list. It might be better to split this up and reconsider the group of groups later on. We have a future use case which might need this functionality. However, it has a lot of other challenges as well since the devices might be roaming over tenants as well…

[BobClaerhout]

@BobClaerhout

Just had one remark about the documentation.

Which is? where can I find it? Does it prevent this issue from being closed? If not, can you close it?

On the PR. I think we close this. It’s just a details.