Server

For WasmEdge to become a cloud-native runtime for microservices, it needs to support HTTP servers. By its very nature, the HTTP server is always asynchronous. In this chapter, we will cover simple HTTP servers based on the wrap API, as well as the low-level hyper API. For HTTP clients in WasmEdge, please see the previous chapter.

备注

Before we start, ensure you have Rust and WasmEdge installed.

The warp API

Use the warp API to create an asynchronous HTTP server. Build and run the example in WasmEdge as follows.

git clone https://github.com/WasmEdge/wasmedge_hyper_demo
cd wasmedge_hyper_demo/server-warp

# Build the Rust code
cargo build --target wasm32-wasi --release
# Use the AoT compiler for better performance
wasmedgec target/wasm32-wasi/release/wasmedge_warp_server.wasm wasmedge_warp_server.wasm

# Run the example
wasmedge wasmedge_warp_server.wasm

Then from another terminal, you can request the server. The HTTP server echoes the request data and sends back the response.

$ curl http://localhost:8080/echo -X POST -d "WasmEdge"
WasmEdge

In your Rust application, import the WasmEdge-adapted warp crate, which uses a special version of single-threaded Tokio adapted for WebAssembly. Just add the following lines to your Cargo.toml.

[dependencies]
tokio_wasi = { version = "1", features = ["rt", "macros", "net", "time", "io-util"]}
warp_wasi = "0.3"

The Rust example code below shows an HTTP server that echoes back any incoming request.

#[tokio::main(flavor = "current_thread")]
async fn main() {
    // GET /
    let help = warp::get()
        .and(warp::path::end())
        .map(|| "Try POSTing data to /echo such as: `curl localhost:8080/echo -XPOST -d 'hello world'`\n");

    // POST /echo
    let echo = warp::post()
        .and(warp::path("echo"))
        .and(warp::body::bytes())
        .map(|body_bytes: bytes::Bytes| {
            format!("{}\n", std::str::from_utf8(body_bytes.as_ref()).unwrap())
        });

    let routes = help.or(echo);
    warp::serve(routes).run(([0, 0, 0, 0], 8080)).await
}

The hyper API

The warp crate is convenient to use. But oftentimes, developers need access to lower level APIs. The hyper crate is an excellent HTTP library for that. Build and run the example in WasmEdge as follows.

git clone https://github.com/WasmEdge/wasmedge_hyper_demo
cd wasmedge_hyper_demo/server

# Build the Rust code
cargo build --target wasm32-wasi --release
# Use the AoT compiler to get better performance
wasmedgec target/wasm32-wasi/release/wasmedge_hyper_server.wasm wasmedge_hyper_server.wasm

# Run the example
wasmedge wasmedge_hyper_server.wasm

Then from another terminal, you can request the server. The HTTP server echoes the request data and sends back the response.

$ curl http://localhost:8080/echo -X POST -d "WasmEdge"
WasmEdge

In your Rust application, import the WasmEdge adapted hyper crate, which uses a special version of single threaded Tokio that is adapted for WebAssembly. Just add the following line to your Cargo.toml.

[dependencies]
tokio_wasi = { version = "1", features = ["rt", "macros", "net", "time", "io-util"]}
hyper_wasi = "0.15.0"

The Rust example code below shows an HTTP server that echoes back any incoming request.

async fn echo(req: Request<Body>) -> Result<Response<Body>, hyper::Error> {
    match (req.method(), req.uri().path()) {
        // Serve some instructions at /
        (&Method::GET, "/") => Ok(Response::new(Body::from(
            "Try POSTing data to /echo such as: `curl localhost:8080/echo -XPOST -d 'hello world'`",
        ))),

        // Simply echo the body back to the client.
        (&Method::POST, "/echo") => Ok(Response::new(req.into_body())),

        (&Method::POST, "/echo/reversed") => {
            let whole_body = hyper::body::to_bytes(req.into_body()).await?;

            let reversed_body = whole_body.iter().rev().cloned().collect::<Vec<u8>>();
            Ok(Response::new(Body::from(reversed_body)))
        }

        // Return the 404 Not Found for other routes.
        _ => {
            let mut not_found = Response::default();
            *not_found.status_mut() = StatusCode::NOT_FOUND;
            Ok(not_found)
        }
    }
}

Server

The warp API​

The hyper API​

The warp API

The hyper API