WAGI for WebAssembly Applications: Building Gateway Interfaces and Server-Side Workflows

**WAGI for WebAssembly Applications: Building Gateway Interfaces and Server-Side Workflows** is a practical and forward-looking guide to designing modern gateway interfaces and server-side workflows with WebAssembly. It introduces WAGI from first principles, explaining how WebAssembly's execution model, compact binary format, and sandboxed runtime make it a strong foundation for portable, secure, and high-performance server-side applications. The book also traces the evolution from CGI to WAGI and shows how the WebAssembly System Interface (WASI) extends WebAssembly beyond the browser, enabling HTTP-driven services that are lightweight, consistent, and easy to deploy across environments.

From there, the book moves into the architecture and day-to-day operation of WAGI, offering clear explanations of request handling, environment management, configuration, and process isolation. Readers will learn how to build WAGI modules in languages such as Rust, TinyGo, and AssemblyScript, with practical guidance for writing, testing, and debugging code that targets WASI. The book emphasizes real-world development patterns and provides a solid foundation for creating modules that are efficient, maintainable, and production-ready.

Security, observability, and deployment are treated as first-class concerns throughout, with detailed coverage of permissions, policy enforcement, module verification, and supply-chain protection. The book also explores advanced deployment strategies, integration with existing systems, and emerging patterns for cloud, edge, and multi-tenant environments. Whether you are building composable microservices, serverless workflows, or portable gateway layers, this book equips you with the knowledge and techniques to use WAGI effectively in modern WebAssembly applications.