Question: I would like to model an application architecture and the time-outs between all the application (e.g. between application A and B there is a time-out of 10 seconds and that between all applications). Which modelling language should I best use for this that it is clear? I don't think UML diagrams will do the trick...

Thanks.

Answer: 
As the documentation states, it is not.

> 
> Time is an abstraction of dates and times. Time is stored internally
>  as the number of seconds with fraction since the Epoch, January 1,
>  1970 00:00 UTC.
> 
> 
> 

There are several things you can do:

* Store it as a string and do regex validation.
* If you are using Postgres and don't mind depending on it, you can use `time` type. This would allow you do things like: `YourModel.where("stime > '13:00:00'")`.
* Store the time of the day in seconds since midnight. This will require you to add some helper methods for creating and scopes for querying data. You might find ActiveSupport's [extension on numeric values](http://edgeguides.rubyonrails.org/active_support_core_extensions.html#time) helpful.
One way of handling this issue, to exemplify Uzbekjon's third point, is storing the time as seconds since midnight in an integer column:

```
stime = Time.now
# => 2016-04-13 10:58:13 -0700
seconds = stime.seconds_since_midnight.to_i
# => 39493

```

You can then retrieve this value and parse it into the time of day when needed:

```
time = Time.at(seconds).utc
# => 1970-01-01 10:58:13 UTC
result = time.strftime("%I:%M")
# => "10:58"

```

Hope it helps!