so the full app means the app, db, public, config and vendor folders if there are plugins?
Pretty much, yes.
If you want to know more about app deployment specifically and RoR in general then you really need to check out railscasts (http://railscasts.com/episodes/133-capistrano-tasks) and grab hold of AWDWR and Programming ruby books from pragprog.comhttp://www.pragprog.com/titles/rails4/agile-web-development-with-rails
they'll tell you pretty much everythuing you need to know and are most ruby and Rails programmers bibles
i'm still finding a tutorial on how to make an web server which monitors temperature
you won't find one
but i do not know how to connect data from the sensor to being displayed in the graph. do i have to learn php for this problem?
Now you are scaring me.
writing code to interface with external devices is extremely advanced stuff, I know how advanced it is because I've written code that interfaces with satellite systems, foetal heart monitoring systems, door entry systems and telephony systems.
The very fact that you are asking about php indicates that you are new to programming not just new to RoR and writing an application that has to deal with external devices is way above some experienced programmers never mind new ones.
You have to understand polling techniques used for the device concerned, system resources, error codes and handling and a whole bunch more.
I'm sure given time you'll get it right but don't expect to be able to do this in a couple of months and get it right!
But no. You don't need php.
Anything php can do, Ruby can do and will mostly do it a lot better.
You need to understand the software used in the device you are hooking up to and you need to know how to interact with the ports that the device is using, you'll need to know how to detect which port the device is connected to and whether or not the device is malfunctioning and this is seriously advanced stuff.
What you want and what you need are too often not the same thing!
When your head is hurting from trying to solve a problem, stop standing on it. When you are the right way up you will see the problem differently and you just might find the solution.
(Quote by me 15th July 2009)