Groups

Description

Each measurement is part of a group. This allows measurements to be grouped together later on. For example, having the measurements cpu and position belonging to the same group, data will be published together on /dc/group/my_group

{
    "cpu": ...,
    "position": ...,
}

Currently, this node is written in python. The main reason for it is that we don't know how to allocate and pass different amount of variables to the TimeSynchronizer. In python it is quite simple, but not so in C++.

Node parameters

Parameter	Description	Type	Default
groups	Groups to enable	list[str]	N/A

Group parameters

Parameter	Description	Type	Default
inputs	Name of the input topics to group	list[str]	N/A
output	Output topic to send the data to	str	"/dc/group/{group}"
sync_delay	Delay to wait during all subscriber data need to reach before being published again	float	5.0
group_key	Dictionary key under which data is grouped	str	{group_name}
exclude_keys	List of keys to exclude from the published data. Data depth is separated by a dot	list[str]	N/A
tags	Destination names, used to know where data will be forwarded to	list[str]	N/A
nested_data	Whether measurements are nested dictionaries or flat	bool	false
include_group_name	Include group name in the JSON as key="name" and value=<group_key>	bool	true

Example

group_server:
  ros__parameters:
    groups: ["map", "memory_uptime"]
    memory_cpu:
      inputs: ["/dc/measurement/memory", "/dc/measurement/cpu"]
      output: "/dc/group/memory_cpu"
      sync_delay: 5.0
      group_key: "memory_cpu"
      tags: ["flb_pgsql"]
    memory_uptime:
      inputs: ["/dc/measurement/memory", "/dc/measurement/uptime"]
      output: "/dc/group/memory_uptime"
      sync_delay: 5.0
      group_key: "memory_uptime"
      tags: ["flb_stdout"]
    cameras:
      inputs: ["/dc/measurement/camera"]
      output: "/dc/group/cameras"
      sync_delay: 5.0
      group_key: "cameras"
      tags: ["flb_minio", "flb_stdout"]
    map:
      inputs: ["/dc/measurement/map"]
      output: "/dc/group/map"
      sync_delay: 5.0
      group_key: "map"
      tags: ["flb_minio", "flb_stdout"]