# webmachine-rust
Port of Webmachine-Ruby (https://github.com/webmachine/webmachine-ruby) to Rust.
[](https://travis-ci.org/uglyog/webmachine-rust)
webmachine-rust is a port of the Ruby version of webmachine. It implements a finite state machine for the HTTP protocol
that provides semantic HTTP handling (based on the [diagram from the webmachine project](https://webmachine.github.io/images/http-headers-status-v3.png)).
It is basically a HTTP toolkit for building HTTP-friendly applications using the [Hyper](https://crates.io/crates/hyper) rust crate.
Webmachine-rust works with Hyper and sits between the Hyper Handler and your application code. It provides a resource struct
with callbacks to handle the decisions required as the state machine is executed against the request with the following sequence.
REQUEST -> Hyper Handler -> WebmachineDispatcher -> WebmachineResource -> Your application code -> WebmachineResponse -> Hyper -> RESPONSE
## Features
- Handles the hard parts of content negotiation, conditional requests, and response codes for you.
- Provides a resource struct with points of extension to let you describe what is relevant about your particular resource.
## Missing Features
Currently, the following features from webmachine-ruby have not been implemented:
- Visual debugger
- Streaming response bodies
## Implementation Deficiencies:
This implementation has the following deficiencies:
- Automatically decoding request bodies and encoding response bodies.
- No easy mechanism to generate bodies with different content types (e.g. JSON vs. XML).
- No easy mechanism for handling sub-paths in a resource.
- Dynamically determining the methods allowed on the resource.
## Getting started with Hyper
Follow the getting started documentation from the Hyper crate to setup a Hyper service for your server.
You need to define a WebmachineDispatcher that maps resource paths to your webmachine resources (WebmachineResource).
Each WebmachineResource defines all the callbacks (via Closures) and values required to implement a resource.
Note: This example uses the maplit crate to provide the `btreemap` macro and the log crate for the logging macros.
```rust
use webmachine_rust::*;
use webmachine_rust::context::*;
use webmachine_rust::headers::*;
use serde_json::{Value, json};
use std::io::Read;
use std::net::SocketAddr;
use std::convert::Infallible;
use std::sync::Arc;
use maplit::btreemap;
use tracing::error;
use hyper_util::rt::TokioIo;
use tokio::net::TcpListener;
use hyper::server::conn::http1;
use hyper::service::service_fn;
use hyper::{body, Request};
async fn start_server() -> anyhow::Result<()> {
// setup the dispatcher, which maps paths to resources. We wrap it in an Arc so we can
// use it in the loop below.
let dispatcher = Arc::new(WebmachineDispatcher {
routes: btreemap!{
"/myresource" => WebmachineResource {
// Methods allowed on this resource
allowed_methods: vec!["OPTIONS", "GET", "HEAD", "POST"],
// if the resource exists callback
resource_exists: callback(&|_, _| true),
// callback to render the response for the resource
render_response: callback(&|_, _| {
let json_response = json!({
"data": [1, 2, 3, 4]
});
Some(json_response.to_string())
}),
// callback to process the post for the resource
process_post: callback(&|_, _| /* Handle the post here */ Ok(true) ),
// default everything else
.. WebmachineResource::default()
}
}
});
// Create a Hyper server that delegates to the dispatcher. See https://hyper.rs/guides/1/server/hello-world/
let addr: SocketAddr = "0.0.0.0:8080".parse()?;
let listener = TcpListener::bind(addr).await?;
loop {
let dispatcher = dispatcher.clone();
let (stream, _) = listener.accept().await?;
let io = TokioIo::new(stream);
tokio::task::spawn(async move {
if let Err(err) = http1::Builder::new()
.serve_connection(io, service_fn(|req: Request<body::Incoming>| dispatcher.dispatch(req)))
.await
{
error!("Error serving connection: {:?}", err);
}
});
}
Ok(())
}
```
## Example implementations
For an example of a project using this crate, have a look at the [Pact Mock Server](https://github.com/pact-foundation/pact-core-mock-server/tree/main/pact_mock_server_cli) from the Pact reference implementation.