Vernon's book Implementing DDD and modeling of underlying concepts

hi




Following questions all refer to examples presented in Implementing DDD
<http://www.amazon.com/Implementing-Domain-Driven-Design-Vaughn-Vernon/d\
p/0321834577/ref=sr_1_1?s=books&ie=UTF8&qid=1372171039&sr=1-1&keywords=i\
mplementing+domain-driven+design>




In article we can see from Figure 6 that both BankingAccount and
PayeeAccount represent the same underlying concept of Banking Account BA





1. On page 64 author gives an example of a publishing organization,
where the life-cycle of a book goes through several stages ( proposing a
book, editorial process, translation of the book ... ) and at each of
those stages this book has a different definition.




Each stage of the book is defined in a different Bounded Context, but do
all these different definitions still represent the same underlying
concept of a Book, just like both BankingAccount and PayeeAccount
represent the same underlying concept of a BA?




2.

a) I understand why User shouldn't exist in Collaboration Context ( CC
), but instead should be defined within Identity and Access Context IAC
( page 65 ). But still, do User ( IAC ), Moderator ( CC ), Author ( CC
), Owner ( CC ) and Participant ( CC ) all represent different aspects
of the same underlying concept?



b) If yes, then this means that CC contains several model elements (
Moderator, Author, Owner and Participant ), each representing different
aspect of the same underlying concept ( just like both BankingAccount
and PayeeAccount represent the same underlying concept of a BA ). But
isn't this considered ( according to Evans ) a Duplication of concepts,
since several model elements in CC represent the same underlying
concept?




c - If Moderator, Author ... don't represent the same underlying
concept, then what underlying concept does each represent?




3. In an e-commerce system, the term Customer has multiple meanings (
page 49 ): When user is browsing the Catalog, Customer has different
meaning than when user is placing an Order.




But do these two different definitions of a Customer represent the same
underlying concept, just like both BankingAccount and PayeeAccount
represent the same underlying concept of a BA?




thanks