Architecture

Uzumibi separates the Ruby application from the platform-specific host.

HTTP request or platform event
            |
            v
Platform adapter (JavaScript or Rust)
            |
     compact byte buffer
            |
            v
Wasm module
  + mruby/edge VM
  + uzumibi-gem
  + embedded Ruby bytecode
            |
            v
Ruby Router or Queue Consumer

Build time

The generated Rust build script compiles the Ruby source into mruby bytecode and embeds it in the Wasm module or native application. Changing Ruby code therefore requires a rebuild.

Runtime

For HTTP applications, the platform adapter serializes the request method, path, query string, selected headers, and body into a buffer. uzumibi-gem constructs an Uzumibi::Request, dispatches the matching route, and serializes the returned Uzumibi::Response.

The transport is implemented separately for each template:

• Cloudflare Workers uses a JavaScript Worker around a wasm32-unknown-unknown module.
• Fastly and Spin run WASI-oriented Rust adapters.
• Cloud Run runs a native Rust HTTP server.
• Service Worker and Web Worker templates use browser JavaScript hosts.

Optional host calls

Some operations require calling back from Wasm into the host. On Cloudflare, the enable-external and queue features build the Wasm module with Asyncify so Ruby code can wait for asynchronous Workers APIs such as fetch, KV, and Queues.

These APIs are platform adapter features, not universal uzumibi-gem APIs.