Crate wasm_plugin_host

A low-ish level tool for easily hosting WASM based plugins.

The goal of wasm_plugin is to make communicating across the host-plugin boundary as simple and idiomatic as possible while being unopinionated about how you actually use the plugin.

Plugins should be written using wasm_plugin_guest

Loading a plugin is as simple as reading the .wasm file off disk.

let mut plugin = WasmPluginBuilder::from_file("path/to/plugin.wasm")?.finish()?;

Calling functions exported by the plugin takes one of two forms. Either the function takes no arguments and returns a single serde deserializable value:

let response: ResultType = plugin.call_function("function_name")?;

Or it takes a single serializable argument and returns a single result:

let message = Message::default();
let response: ResultType = plugin.call_function_with_argument("function_name", &message)?;

If the inject_getrandom feature is selected then the host’s getrandom will be injected into the plugin which allows rand to be used in the plugin. inject_getrandom is selected by default.

Currently serialization uses either bincode or json, selected by feature: serialize_bincode: Uses serde and bincode. It is selected by default. serialize_json: Uses serde and serde_json. `serialize_nanoserde_json’: Uses nanoserde.

Bincode is likely the best choice if all plugins the system uses will be written in Rust. Json is useful if a mix of languages will be used.

Limitations

There is no reflection so you must know up front which functions a plugin exports and their signatures.

Modules

errors
serialization

Structs

WasmPlugin	A loaded plugin
WasmPluginBuilder	Constructs a WasmPlugin

Enums

Extern

An Extern is the runtime representation of an entity that can be imported or exported.

Traits

HostFunction	The HostFunction trait represents the set of functions that can be used as host function. To uphold this statement, it is necessary for a function to be transformed into a pointer to VMFunctionBody.
ImportableFn	A marker trait for Fn types who’s arguments and return type can be serialized and are thus safe to import into a plugin;
ImportableFnWithContext	A marker trait for Fn types who’s arguments and return type can be serialized and are thus safe to import into a plugin;