phd - When to publish a book?

I am presently doing MSc (Information Technology) in India. I really like teaching and have a passion for it. Based on my Masters degree I will get a designation of Assistant professor (hope so I get it!), but to be a Professor we need a PhD degree, so I was thinking of doing a Phd (Computer Science) not right after the Masters but after some years of teaching experience. At present I don't have much knowledge about PhD (nearly zero).

I know we need to publish the thesis in PhD,but my question is do we have to publish books (about courses like Java, Operating System etc, since I am talking about IT/CS i gave these subjects) in PhD? This is because right now in my Masters I was thinking of publishing a book for a local course of Bachelors (BSc IT) in my region.

So if we need to publish certain number books in PhD, then I should wait for writing and publishing that local book till I join a PhD or should I start writing and publish it right in my Masters and this published book will be considered in my PhD?

Answer

A PhD should be based on an original contribution to knowledge. This is generally published at research conferences and in journals.

Material, such as a book, treating topics that already are well-known generally do not contribute to the PhD dissertation. The only exception is if you were to write an excellent synthesis of a field, then that could be included as a part of your PhD dissertation, as such a thing would be an original contribution to knowledge.

Writing a book may actually hinder your progress to obtaining a PhD, because it too will take a lot of time. That said, I do not wish to encourage you on this issue. But there are already plenty of books about Java and Operating Systems, and I questions the value of writing more.