APIs enable breakthrough innovation and digital transformation in organizations and ecosystems of all kinds. To create user-friendly, reliable and well-performing APIs, architects, designers, and developers need expert design guidance. This practical guide cuts through the complexity of API conversations and their message contents, introducing comprehensive guidelines and heuristics for designing APIs sustainably and specifying them clearly, for whatever technologies or platforms you use.

In Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges, five expert architects and developers cover the entire API lifecycle, from launching projects and establishing goals through defining requirements, elaborating designs, planning evolution, and creating useful documentation. They crystallize the collective knowledge of many practitioners into 44 API design patterns, consistently explained with context, pros and cons, conceptual solutions, and concrete examples. To make their pattern language accessible, they present a domain model, a running case study, decision narratives with pattern selection options and criteria, and walkthroughs of real-world projects applying the patterns in two different industries.

• Identify and overcome API design challenges with patterns
• Size your endpoint types and operations adequately
• Design request and response messages and their representations
• Refine your message design for quality
• Plan to evolve your APIs
• Document and communicate your API contracts
• Combine patterns to solve real-world problems and make the right tradeoffs

"This book provides a healthy mix of theory and practice, containing numerous nuggets of deep advice but never losing the big picture . . . grounded in real-world experience and documented with academic rigor applied and practitioner community feedback incorporated. I am confident that [it] will serve the community well, today and tomorrow."

--Prof. Dr. Dr. h. c. Frank Leymann, Managing Director, Institute of Architecture of Application Systems, University of Stuttgart