With the IT landscape outlined, the goals wanted in broad terms is that it would be normal to drill into identifying the value propositions of APIs on the different areas, qualifying success criteria, and so on. With this, the domain partitions would be further analyzed to ensure that they're well understood.
For a fuller understanding of Domain Driven Design, the best source of information is Eric J. Evans' book or this website
http://www.methodsandtools.com/archive/archive.php?id=97.
http://www.methodsandtools.com/archive/archive.php?id=97.
However, this book isn't aiming to be a benchmark on analysis and design, but it aims to draw out the issues relating to APIs and the adoption of a suitable platform.
To meet these identified goals several APIs have been identified. The next section works through what these APIs are.