Learning API Styles

Application programming interfaces are a key part of software development, enabling communication between applications and services. This book provides a practical understanding of API concepts, covering API design, API styles, API tools, microservices, security, and practical implementation approaches.

The book introduces transmission model approaches, including pull model, push model, and streaming, along with legacy system issues. It also covers endpoint design, URI, URL, HTTP methods, and status codes. Readers will explore SOAP-based API, REST API, GraphQL, RPC, WebSocket, Webhooks, and API tools such as Swagger, SDKs, stubs, Postman, and Karate Labs. The book further explores microservices architecture, covering service communication, data modelling, resilience, governance, management, and platform concepts. It introduces advanced patterns including CQRS, SAGA pattern, BFF, and service mesh, along with API performance and security concepts such as Basic Auth, OAuth 2.0, JWT, API keys, and Transport Layer Security.

By the end of this book, the readers will be able to evaluate API technologies confidently, design and evolve APIs with empathy for consumers, and create API ecosystems that scale with product needs and team maturity.

WHAT YOU WILL LEARN
● Overview of API styles like REST, GraphQL, gRPC, WebSockets, and Webhooks.
● Learn how different styles handle CRUD, filtering, error handling, and pagination.
● Apply OpenAPI, GraphQL SDL, Protocol Buffers, and AsyncAPI for contract design.
● Learn advanced patterns including CQRS, SAGA pattern, BFF, and service mesh.
● Understand API performance through OAuth 2.0, JWT, and TLS implementation.
● Build practical solutions using Java 21, Spring Boot 3, and practical use cases.

WHO THIS BOOK IS FOR
This book is for software developers, backend engineers, API and solution architects, technical product managers, DevOps and platform engineers, and advanced students with basic computer engineering knowledge who want to understand API technologies, design approaches, integrations, and application development.

1. Fundamentals of APIs
2. API Design Fundamentals
3. Types of API Style
4. Building APIs with Tools
5. Microservices With APIs
6. Advanced Architectural Patterns and Implementation
7. API Security
8. Practical Use Cases
9. Future of API

Siddharth Gelda is a software professional with 14+ years’ experience in the software industry, with deep specialization in the API, microservices, Java, and spring technologies. He has focused exclusively on designing, developing, and managing enterprise-grade microservices and APIs, contributing to large-scale, mission-critical projects across diverse industries.

His expertise lies in building complex API ecosystems with multi-layered security architectures, ensuring seamless, secure, and scalable integrations between systems. He has played pivotal roles in enabling digital transformation initiatives by architecting robust API solutions that adhere to best practices in security (OAuth 2.0, JWT, mutual TLS, API gateways, and rate limiting), performance optimization, and governance.