First, I would really like to thank you Jitendra for helping me out as I was stuck with this thing for a long time now.
I started afresh for the Push Notification procedure right from creating my own webservice by following Marvin Hoffmann`s blog series using JDBC and Integration Gateway. I then followed your link SMP 3.0 : REST API Application Development.
This finally led me to create a successful notification message as below (referring http://scn.sap.com/servlet/JiveServlet/showImage/102-49529-4-440047/image3.PNG posted by you) :
But I was not able to view the logs in my server :
Is this because I would be missing something. I would also like to state that I was not able to access the web-service url directly from integration gateway but after registering it in SMP, everything worked smoothly.