If your book is being published by a commercial publisher, they will assign an ISBN to it.
An International Standard Serial Number (ISSN) is an eight-digit number that uniquely identifies a serial publication, such as a journal or periodical. They are used by publishers, booksellers and libraries for ordering and stock control purposes. We strongly recommend that the publisher/editor of a journal apply for an ISSN. This can be done retrospectively, even if it has been some time since the journal was first published.