This is a demo showing WASI Preview2 sockets support. This is an early demo using the APIs directly; in time we'll add standard library support so that this isn't necessary.

Clone the preview2-prototyping repository, which contains both the wit IDL interfaces we'll use and the host implementation, and build the host implementation:

$ git clone https://github.com/bytecodealliance/preview2-prototyping
[...]
$ cd preview2-prototyping
$ git checkout 408f0bf
[...]
$ cd host
$ cargo build
[...]
$ cd ../..
$ PATH="$PWD/preview2-prototyping/target/debug:$PATH"

This creates a command called host which includes Wasmtime and the Preview2 host implementation.

Then build and start the server (adjusting the path to your local directory):

$ cd echo-server
$ cargo component build
[...]
    Creating component /home/demo/world-of-wasi-demo/echo-server/target/wasm32-wasi/debug/echo_server.wasm
$ host /home/demo/world-of-wasi-demo/echo-server/target/wasm32-wasi/debug/echo_server.wasm
Listening on IpSocketAddress::Ipv4(Ipv4SocketAddress { port: 42803, address: (127, 0, 0, 1) })

Note the port number that it prints out; we'll need to provide that to the client.

In another windows, build and run the client, passing it the port number:

$ cd echo-client
$ cargo component build
[...]
    Creating component /home/demo/world-of-wasi-demo/echo-client/target/wasm32-wasi/debug/echo_client.wasm
$ host /home/demo/world-of-wasi-demo/echo-client/target/wasm32-wasi/debug/echo_client.wasm 42803
Sending our message!
Receving the response!
Success!

If everything worked, the server will print this:

Accepted a connection!
Received input!
Sent output!
Received input!
Sent output!
The client closed the connection!

Install Rust and protoc, and then install cargo component, and then create new projects for the echo-server and echo-client.

$ cargo-component new --lib echo-server
     Created component `echo-server` package
$ cargo-component new --lib echo-client
     Created component `echo-client` package

The use of --lib is a temporary workaround, though these will use the command world and be runnable commands.

Delete the wit/world.wit file, and change the package.metadata.component in echo-server/Cargo.toml to point to the wit in the preview2-prototyping repo we checked out above:

[package.metadata.component]
target = { path = "../preview2-prototyping/wit", world = "command" }

Then put the code for the echo server and echo clients in echo-server/src/lib.rs and echo-client/src/lib.rs.