HttpServer trait?

[zhangzqs]

I found http client in embedded-svc it's a Connection wrapper

embedded-svc/src/http/client.rs

Lines 7 to 11 in ad0016b

	pub struct Client<C>(C);
	impl<C> Client<C>
	where
	C: Connection,

But is there any http server trait?

reference to esp-idf-svc:
https://github.com/esp-rs/esp-idf-svc/blob/2191e60cb8b85fba5e64bd09a55028955d38792d/src/http/server.rs#L405-L412
https://github.com/esp-rs/esp-idf-svc/blob/2191e60cb8b85fba5e64bd09a55028955d38792d/src/http/server.rs#L438-L440

Maybe we can use trait code as follows?

pub trait Server<'a> {
    type Conn<'r>: Connection;
    type HttpServerError: std::error::Error;

    fn handler<H>(
        &mut self,
        uri: &str,
        method: Method,
        handler: H,
    ) -> Result<&mut Self, Self::HttpServerError>
    where
        H: for<'r> Handler<Self::Conn<'r>> + Send + 'a;

    fn fn_handler<F>(
        &mut self,
        uri: &str,
        method: Method,
        f: F,
    ) -> Result<&mut Self, Self::HttpServerError>
    where
        F: for<'r> Fn(Request<&mut Self::Conn<'r>>) -> HandlerResult + Send + 'a,
    {
        self.handler(uri, method, FnHandler::new(f))
    }
}

[ivmarkov]

Such a trait used to be there long time ago.

I have removed it, because this trait is impossible to implement without using alloc. And you need alloc to turn the generic H: Handler handler into a dyn Handler instance, by potentially using boxing, as in Box<dyn Handler>.

Since embedded-svc strives to have all its traits implementable in no_std and without heap allocations, I therefore removed it in later versions.

While this trait might be useful, its usage is very limited - as in it can only abstract the code that registers your handlers. Abstracting the handlers themselves is way more useful, as that way you can re-use them across many HTTP servers.