Overview

The wasmedge-sdk crate defines a group of high-level Rust APIs, which are used to build up business applications.

Notice that wasmedge-sdk requires Rust v1.63 or above in the stable channel.

Versioning Table

The following table provides the versioning information about each crate of WasmEdge Rust bindings.

Build

To use or build the wasmedge-sdk crate, the WasmEdge library is required.

• If you choose to use install.sh to install WasmEdge Runtime on your local system. Please use WASMEDGE_INCLUDE_DIR and WASMEDGE_LIB_DIR to specify the paths to the include and lib directories, respectively. For example, use the following commands to specify the paths after using bash install.sh --path=$HOME/wasmedge-install to install WasmEdge Runtime on Ubuntu 20.04:

  export WASMEDGE_INCLUDE_DIR=$HOME/wasmedge-install/include 
  export WASMEDGE_LIB_DIR=$HOME/wasmedge-install/lib
  

• If you choose to manually download WasmEdge Runtime binary from WasmEdge Releases Page, it is strongly recommended to place it in $HOME/.wasmedge directory. It looks like below on Ubuntu 20.04. wasmedge-sdk will search the directory automatically, you do not have to set any environment variables for it.

  // $HOME/.wasmedge/
  .
  |-- bin
  |   |-- wasmedge
  |   `-- wasmedgec
  |-- include
  |   `-- wasmedge
  |       |-- enum.inc
  |       |-- enum_configure.h
  |       |-- enum_errcode.h
  |       |-- enum_types.h
  |       |-- int128.h
  |       |-- version.h
  |       `-- wasmedge.h
  `-- lib64
      |-- libwasmedge_c.so
      `-- wasmedge
          `-- libwasmedgePluginWasmEdgeProcess.so
  
  5 directories, 11 files
  

Enable WasmEdge Plugins

If you'd like to enable WasmEdge Plugins (currently, only available on Linux platform), please use WASMEDGE_PLUGIN_PATH environment variable to specify the path to the directory containing the plugins. For example, use the following commands to specify the path on Ubuntu 20.04:

export WASMEDGE_PLUGIN_PATH=$HOME/.wasmedge/lib/wasmedge

Example

A quick-start example below is using wasmedge-sdk to run a WebAssembly module written with its WAT format (textual format):

// If the version of rust used is less than v1.63, please uncomment the follow attribute.
// #![feature(explicit_generic_args_with_impl_trait)]

use wasmedge_sdk::{Executor, FuncTypeBuilder, ImportObjectBuilder, Module, Store};
use wasmedge_sys::WasmValue;
use wasmedge_types::wat2wasm;

#[cfg_attr(test, test)]
fn main() -> anyhow::Result<()> {
    let wasm_bytes = wat2wasm(
        br#"
(module
  ;; First we define a type with no parameters and no results.
  (type $no_args_no_rets_t (func (param) (result)))

  ;; Then we declare that we want to import a function named "env" "say_hello" with
  ;; that type signature.
  (import "env" "say_hello" (func $say_hello (type $no_args_no_rets_t)))

  ;; Finally we create an entrypoint that calls our imported function.
  (func $run (type $no_args_no_rets_t)
    (call $say_hello))
  ;; And mark it as an exported function named "run".
  (export "run" (func $run)))
"#,
    )?;

    // We define a function to act as our "env" "say_hello" function imported in the
    // Wasm program above.
    fn say_hello_world(_: CallingFrame, _: Vec<WasmValue>) -> Result<Vec<WasmValue>, u8> {
        println!("Hello, world!");

        Ok(vec![])
    }

    // create an import module
    let import = ImportObjectBuilder::new()
        .with_func::<(), ()>("say_hello", Box::new(say_hello_world))?
        .build("env")?;

    // loads a wasm module from the given in-memory bytes
    let module = Module::from_bytes(None, &wasm_bytes)?;

    // create an executor
    let mut executor = Executor::new(None, None)?;

    // create a store
    let mut store = Store::new()?;

    // register the module into the store
    store.register_import_module(&mut executor, &import)?;
    let extern_instance = store.register_named_module(&mut executor, "extern", &module)?;

    // get the exported function "run"
    let run = extern_instance.func("run").ok_or(anyhow::Error::msg(
        "Not found exported function named 'run'.",
    ))?;

    // run host function
    run.call(&mut executor, [])?;

    Ok(())
}

[Click for more examples]

See also

• WasmEdge Runtime
• WasmEdge C API Documentation