Real-time oriented language?
What is real-time
First we have to define what real-time mean.
Of course depending on how your tool will work against the physical environment pure real-time couldn't be effectively done, mostly because there will be a lot of third party dependencies.
If you are building embed stuff by using microcontrollers like arduino, the language to use will be limited by the hardware, but with more complex stuff like Raspberry Pi, the language choice is very wide.
Granularity
This is depending on what you are measuring, if you're working with:
- weather temperatures, one read each 10 minute could be enough
- people height or weight, one or maybe four read by day
- server status, between 1 second for fine debugging to approx 1 hour for quiet unimportant secondary server.
- atomic collision count: something finer...
Event based reading
The right (better) way for collecting data is based on value change event... whenever the device do permit it.
Your tool have to not poll values from device, but the device have to send values to your tool, when they change.
This could be done by using an hardware interrupt trigger or by using port protocole like RS-232 staying listening on some serial port, for sample.
Monitoring environment
The last thing to be warned is how legitimate user will interact with.
If you're building embed standalone device, like robot, you may use graphic libraries to interact with touch screen.
If you're building web based monitor, you may have to keep in mind that the client could be an old 800x600 monochrome screen, using poor internet connection and small processor... But depending on final goal if you may interact with clients, you could ensure strong hardware and strong internet connections. Anyway you have to watch for connexion loosing and event for communication delay between server and client. There is mostly third party dependencies.
Which programming language?
From there, the language choice is wide and clearly depend on
- your knowledge.
- granularity requested (by using event-based too, of course)
- the amount of time you have to build the tool (money;)
- delay, co-workers...
- kind of device
- kind of monitoring
- some other political reasons
You could build real-time monitoring engine by using bash and sql only, I've seen sophisticated engines that was built under postgresql only... I've personally built a web based, solar energy monitor by using perl, mysql and javascript.