Here is a collection of resources I have found during my research into Service Oriented Architecture.

Building Microservices: Designing Fine-Grained Systems

Of all the introductory resources I have seen, this book is probably the best. The book is concise, high-level, and focuses on concepts instead of specific technologies or implementations concerning the concepts presented. You will learn how team structure directly affects service structure. You will dive into the full application life-cycle, from building to deployment to monitoring. The book does a great job of presenting various migration (from monolith and from other service) strategies while being just prescriptive enough that you get a sense of what the best options are.

Microsoft Azure - Cloud Design Patterns

Don’t let the name fool you, this is a comprehensive overview of SOA design patterns, and is not specific to Azure Cloud. I actually discovered this resource as I was putting together a blog page to give an overview of SOA design patterns, but I think this serves that purpose much better than I could!