# waPC
This is the Rust implementation of the **waPC** standard for WebAssembly host runtimes. It allows any WebAssembly module to be loaded as a guest and receive requests for invocation as well as to make its own function requests of the host.
## Example
The following is a simple example of synchronous, bi-directional procedure calls between a WebAssembly host runtime and the guest module.
```rust
extern crate wapc;
use wapc::prelude::*;
pub fn main() -> Result<(), Box<dyn std::error::Error>> {
let module = load_file();
let mut host = WapcHost::new(&module)?;
wapc::set_host_callback(host_callback);
let res = host.call("wapc:sample!Hello", b"this is a test")?;
assert_eq!(res, b"hello world!");
Ok(())
}
fn host_callback(op: &str, payload: &[u8]) -> Result<Vec<u8>, Box<dyn std::error::Error>> {
println!("Guest invoked '{}' with payload of {} bytes", op, payload.len());
Ok(vec![])
}
```