clock_gettime and rmw_uros functions

[Anandhu-Sudha]

Is this clock_gettime() strictly required for the microros to work? How can i implemet that? there is no elaborated document related to the implementation of this, i have given the values in seconds and nano seconds to the sec and nsec variables, but still the executor_spin_some() is not working, how can i debug this issue? if it's issue with my timer program, can i use the rmw_uros functions to provide the time to implement the clock_gettime() .
Thank you.