This chapter covers Service Identification and Design - essentially identifying what services you already have and which new ones do you need.
The authors introduced the concept of 3 hierarchical architecture layers in Chapter 1 -
Business / Information and Technical. So essentially you end up with services on all 3 levels, which need to be identified and designed.
The section on Service Design succinctly covers all you need to know in respect of interface, contract and implementation design. It deals with concepts such as granularity, reusability, idempotency, isolation etc. - really a great checklist for you to follow.
Again the link -
SOA made simple