What is WASI?

Integration is a significant challenge for business owners looking to streamline operations across various environments. When tools are isolated, employees face inefficiencies and frustrations, which can lead to missed opportunities.

The WebAssembly System Interface (WASI) offers a solution by providing common standards for running WebAssembly modules outside of web browsers, allowing for smoother integration with other systems and software used by your company.

Read on to learn more about WASI and discover how adopting it can help optimize processes, boost developer productivity, and take your business to new heights.

What is WASI?

WebAssembly System Interface (WASI) is an initiative designed to expand what WebAssembly (Wasm) can do outside the browser. It provides a standardized system interface (API) for Wasm modules, enabling them to interact with system resources securely and efficiently across various platforms while maintaining consistent behavior.

Wasm vs WASI

While Wasm and WASI may appear similar, they have distinct goals that contribute to optimizing operations. Understanding their differences is crucial for leveraging their combined strengths. Let’s have a closer look:

Wasm

Wasm enables code to run quickly and efficiently on any CPU, allowing the development of applications that perform well everywhere. Its primary focus is executing binary instructions across diverse hardware. 

Key features include:

• Universal use: Write once and run anywhere that supports WebAssembly.

• Speed: Achieves near-native performance due to its compact format and direct compilation.

• Security: Isolates code in a protected space to reduce vulnerabilities.

• Modularity: Divides work into reusable components.

In essence, WebAssembly provides an abstraction over the wide variety of CPUs in use across the industry, allowing code to be portable across these CPUs

How does WASI enhance Wasm?

WASI extends WebAssembly’s capabilities by allowing code to interact with underlying systems. While Wasm focuses on swift execution across platforms, WASI provides additional functionalities. 

Its main strengths include:

• System access: Allows reading and writing files, networking, and more.

• Standardization: Consistent APIs ensure uniform behavior across platforms.

• Security: Minimizes risks by granting only necessary permissions.

• Flexibility: Uses a modular approach to implement only required system interactions.

Despite their differences, Wasm and WASI are designed to work together. Wasm handles efficient universal execution, while WASI provides system-level capabilities, enhancing functionality wherever your code performs critical tasks. Their combined use enables the creation of powerful, cross-platform applications tailored to your requirements.

What is the goal of WASI?

WASI was developed to address specific challenges that arose as WebAssembly (Wasm) gained popularity among businesses. While Wasm excels at running code efficiently across platforms, its limitations hinder broader adoption. 

Let's examine Wasm’s restrictions:

• Restricted access: Wasm operates in a secure environment, which is crucial for security, particularly in browsers. However, this means Wasm cannot directly access system resources such as files or networks. 

• Limited native interactions: Designed primarily for the web, Wasm has minimal interaction with system functions. Without direct access to system APIs, Wasm modules cannot perform tasks like filesystem access or network communication outside browsers. 

• Fragmented tools: The lack of a standardized way for Wasm to interact with resources led developers to rely on environment-specific extensions or custom solutions. These diverse approaches resulted in fragmented tools, causing Wasm module behavior to vary by environment and complicating cross-platform development.

As Wasm extended beyond browsers, the demand for a uniform system interface became critical. This demand led to the development of WASI, which is essential for the following purposes:

• Addressing fragmentation: WASI provides a single set of APIs usable across platforms, ensuring Wasm modules act the same anywhere they run. This simplifies development and reduces compatibility issues, enabling you to build applications for servers, edge devices, and more.

• Enhancing security and portability: It also boosts security by defining a standard interface for system interactions. It follows a capability-based security model, granting Wasm modules only the necessary permissions and lowering risk. 

The APIs of WASI

WASI consists of several essential parts working together to provide a powerful environment for running your WebAssembly applications. These components enhance WebAssembly's functionality, security, and flexibility, making it suitable for many uses beyond browsers. Below are its main components:

APIs

The WASI interface provides APIs that enable your WebAssembly modules to interact with underlying systems. These APIs serve as the interface through which modules perform various tasks, ensuring they have the tools to operate effectively in their environment. The main APIs include:

• File I/O: WASI allows modules to read from and write to files on the host system. This capability enables your modules to manage data storage, configuration files, and user-created content, which is essential for applications that rely on persistent data.

• Networking: The interface includes networking APIs, enabling modules to establish and manage network connections. This capability is crucial for applications that need to communicate over the internet or local networks, supporting tasks ranging from simple HTTP requests to more complex networking operations.

• Time: This interface provides WebAssembly modules with the ability to interact with system clocks to retrieve the current time or measure time intervals. This API is crucial for tasks such as logging events, scheduling tasks, or measuring how long operations take. 

• Randomness: This interface is great for tasks that require high-quality randomness, such as generating encryption keys, creating unique identifiers, or implementing secure protocols.

• Terminal input/output: These APIs deal with standard input, output, and error streams, enabling interaction with the console or other I/O streams.

Looking into the future of WASI

WASI 0.2 continues to evolve, with ongoing efforts to introduce new features and capabilities like sockets, HTTP, key value and blob storage, configuration, messaging, and crypto and a component model. Many industries and organizations are adopting WASI to simplify cross-platform development and enhance the security and performance of business applications.

In the future, the core principles of compatibility and combinability will guide WASI's transition between versions. These principles ensure that your existing WebAssembly applications requiring system access remain functional as WASI advances. Building applications now with current WASI APIs will also keep options open for incorporating upcoming capabilities.

Fastly and WASI

Fastly has been a significant contributor to the development and adoption of Wasm and WASI and continues to contribute to the standards and open-source implementations in the World Wide Consortium (W3C) and the Bytecode Alliance. 

Learn more about how Fastly supports open source and how Fastly Compute enables developers to easily build the best experiences for end users. Start a free trial today.