Given the types of data you mention, I would suggest to use the ROS parameter server for this.
The roslaunch rosparam tag in combination with .yaml files makes for a very convenient way to store and load settings of a ROS application. Example:
camera:
device: /dev/video0
robot:
ip_address: 1.2.3.4
workspace:
area: [0.1, 0.3, 0.2, 0.4]
bins:
- id: 1
area: [0.1, 0.3, 0.2, 0.4]
- id: 4
...
etc.
Whether you load those parameters in the private namespace of nodes, or put them in a separate namespace and then have nodes load "their section" from that namespace would be a design decision only you can make (the former would reduce coupling though, so might perhaps be a better approach).
One thing I'm still wondering about: if you have to edit multiple files "when things change", this may be an indication of a violation of separation of concerns (ie: too many nodes/classes/functions need to be aware of various details to be able to do their work). It may be good to investigate whether all those entities actually need all that information, or whether they could get it from somewhere else (as part of a service request coming in, fi).
are you not using TF?
Edit: reason I ask this and don't directly address your question is I'm wondering whether this is an xy-problem. If you could give a few more examples of the sort of data you're looking to share, perhaps we can give better answers.
Yes I am using TF. I realize I wasn't clear in my original question. For each variable I want to change, there is only ONE corresponding file I need to edit. When my physical set up changes, say I set up the robot in a new area, I need to edit quite variables, and therefore quite a few files. In addition to camera location, there are multiple bins that the arm sorts items in to, whose position and size may change. Workspace area may change size. Most of the edits take place in my main urdf, but a couple are in other places. Perhaps I should edit my urdfs so all the configurable information is my main urdf?
The reason I was hoping to make some sort of global configuration file is because other people will be setting up my project and I want to make configuration as easy ...(more)
Edit: IP address for robotic arm is another variable, one that is not urdf related. Another is camera path location (eg. /dev/video0, /dev/video1)