2.23. Using the 3scale WebAssembly module

The threescale-wasm-auth module is a WebAssembly module that uses a set of interfaces, known as an application binary interfaces (ABI). This is defined by the Proxy-WASM specification to drive any piece of software that implements the ABI so it can authorize HTTP requests against 3scale.

As an ABI specification, Proxy-WASM defines the interaction between a piece of software named host and another named module, program, or extension. The host exposes a set of services used by the module to perform a task, and in this case, to process proxy requests.

The host environment is composed of a WebAssembly virtual machine interacting with a piece of software, in this case, an HTTP proxy.

The module itself runs in isolation to the outside world except for the instructions it runs on the virtual machine and the ABI specified by Proxy-WASM. This is a safe way to provide extension points to software: the extension can only interact in well-defined ways with the virtual machine and the host. The interaction provides a computing model and a connection to the outside world the proxy is meant to have.