Thank you for the reply.
Sir could you please tell me if my approach is correct ?
This is the simple picture I have in mind after reading about Moodle a bit.
I have a cron() method inside my block.
Inside that cron() method of my block,
I write the code to check the moodle database for new assignment deadlines, new quizzes, new resource updates, new forums posts
the code to send SMS via my gateway(I'm going to use Kannel WAP/SMS gateway for this project).
I didn't quite understand your reply since I'm still trying to understand how moodle works and where I should start. Im not familiar with php either but hopefully I'll catch up soon.