WASI
A modular set of standardized APIs enabling WebAssembly programs to securely interact with system resources like files and networks.
What is WASI?
WASI (WebAssembly System Interface) is a standardized set of APIs that allows WebAssembly programs to securely interact with system resources such as files, networks, and other operating system features. It solves the problem of WebAssembly being limited to browser environments by providing a portable, secure interface for running WebAssembly anywhere from cloud servers to edge devices. The project is evolving through multiple preview versions, with Preview 2 offering improved modularity, language support, and virtualizability.
WebAssembly runtime developers, cloud infrastructure engineers, and developers building portable applications that need to run WebAssembly outside browser environments.
Developers choose WASI because it provides a standardized, secure way to run WebAssembly anywhere while maintaining strong security guarantees through capability-based access control and offering better language interoperability than previous approaches.
Overview
WebAssembly System Interface
Use Cases
Best For
- Running WebAssembly applications securely on cloud servers
- Building portable applications that run consistently across different platforms
- Creating edge computing solutions with WebAssembly
- Developing secure serverless functions with WebAssembly
- Implementing plugin systems with isolated WebAssembly components
- Running untrusted code in sandboxed environments with controlled resource access
Not Ideal For
- Applications requiring ultra-low latency where abstraction layers add unacceptable overhead
- Projects deeply integrated with a specific OS's native APIs without need for cross-platform portability
- Teams needing a fully standardized, production-ready system interface without handling preview version migrations
Pros & Cons
Pros
WASI employs a capability-based security model that restricts resource access to explicitly granted permissions, ensuring safe execution of untrusted code in sandboxed environments.
APIs are developed in separate repositories, allowing for independent evolution and specialization, as outlined in the proposals list for flexible integration.
Enables WebAssembly programs to run consistently from cloud servers to edge devices, based on the philosophy of a portable system interface for diverse environments.
Preview 2 uses the Wit IDL to support a wider range of source languages, enhancing interoperability over Preview 1's limitations.
Cons
With Preview 1 and Preview 2 coexisting, developers face fragmentation and must navigate migration challenges until full standardization is achieved, leading to potential instability.
Proposing new APIs requires using the Wit IDL and following a specific template, which can be a barrier for contributors unfamiliar with the system's modular structure.
The secure and portable interface introduces abstraction layers that can add latency compared to direct native system calls, impacting performance-critical applications.
Frequently Asked Questions
Related Projects
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