WASI 0.2: WebAssembly gets a stable system interface

2024-01-25 · Publisher : Bytecode Alliance · Domain : Cloud & DevOps

On 25 January 2024 the WASI Subgroup votes to launch WASI 0.2 (Preview 2): the APIs are declared stable and built on the component model, with two worlds, wasi-cli and wasi-http.

### Background On 25 January 2024, the Bytecode Alliance's WASI Subgroup votes to launch **WASI 0.2**, also called Preview 2 or WASIp2, and declares its APIs stable. WASI, WebAssembly's system interface, is now officially based on the **component model**: modules written in different languages can be assembled and virtualized. ### Key facts - Two "worlds" are defined: `wasi-cli`, a command-line interface close to POSIX (files, sockets, clocks, random numbers), and `wasi-http`, an HTTP proxy world organized around requests and responses. - The component model lets you compose parts without hidden complexity creeping in, in the announcement's wording. - Each component is isolated: there is no global runtime namespace and interfaces can be virtualized. - Cross-language interoperability is a core goal: a component written in one language can be called from another. - The WASI 0.2 APIs are declared stable by the WASI Subgroup. ### Why it matters For platform teams, server-side and edge WebAssembly finally had a stable specification target for runtimes and toolchains. The topic is still young: WASI 0.2 relies on polling mechanisms (pollables) that WASI 0.3 replaces with native async in 2026. For a CIO, it is a maturity signal to watch, not yet a replacement for containers. The announcement stresses composition: putting parts together without complexity creeping in, and virtualizing interfaces. ### Takeaway WASI 0.2 lays WebAssembly's first stable foundation outside the browser; native async follows with WASI 0.3.

Tags : WebAssembly, Cloud natif, Edge, Open Source