Update readme to latest template syntax

sdk/rust/README.md

@@ -2,80 +2,107 @@
 
 The Spin Rust SDK makes it easy to build Spin components in Rust.
 
-### Writing Spin HTTP components in Rust
+### Writing Spin HTTP Components in Rust
 
 This library simplifies writing Spin HTTP components. Below is an example of
 such a component:
 
 ```rust
 // lib.rs
-use anyhow::Result;
-use spin_sdk::{
-    http::{Request, Response},
-    http_component,
-};
+use spin_sdk::http::{IntoResponse, Request, Response};
+use spin_sdk::http_component;
 
 /// A simple Spin HTTP component.
 #[http_component]
-fn hello_world(req: Request) -> Result<Response> {
-    println!("{:?}", req.headers);
-    Ok(Response::new_with_headers(200, &[] "Hello, Fermyon!"))
+fn handle_hello_world(req: Request) -> anyhow::Result<impl IntoResponse> {
+    println!("Handling request to {:?}", req.header("spin-full-url"));
+    Ok(Response::builder()
+        .status(200)
+        .header("content-type", "text/plain")
+        .body("Hello, Fermyon")
+        .build())
 }
 ```
 
-The important things to note in the function above:
+The important things to note about the function above are:
 
-- the `spin_sdk::http_component` macro — this marks the function as the
-  entrypoint for the Spin component
-- the function signature — `fn hello_world(req: Request) -> Result<Response>` —
-`req` can be any number of types including the built in `Request` type or 
-the `http::Request` from the popular `http` crate. Likewise, the response type
-can be many things including the built in `Response` type or the `http::Response` type
-from the `http` crate.
+- the `spin_sdk::http_component` macro marks the function as the entry point for the Spin component,
+- in the function signature (`fn handle_hello_world(req: Request) -> anyhow::Result<impl IntoResponse>`), `req` can be any number of types, including the built-in `Request` type or the `http::Request` from the popular `http` crate
+- in the function signature, the response type can be many things, including `anyhow::Result<impl IntoResponse>` (as shown above) or the `http::Response` type from the `http` crate (e.g. `Result<Response>`). Note - Using the `http` crate will require you to add it, e.g. `cargo install http`.
 
-### Making outbound HTTP requests
+### Making Outbound HTTP Requests
 
-Let's see an example where the component makes an outbound HTTP request to a
-server, modifies the result, then returns it:
+Let's see an example where the component makes an outbound HTTP request to a server, modifies the result, and then returns it:
 
 ```rust
+use anyhow::Result;
+use spin_sdk::{
+    http::{IntoResponse, Request, Method, Response},
+    http_component,
+};
+
 #[http_component]
-async fn hello_world(_req: Request) -> Result<Response> {
-    let mut res: http::Response<String> = spin_sdk::http::send(
-        http::Request::builder()
-            .method("GET")
-            .uri("https://fermyon.com")
-            .body(())?,
-    ).await?;
+async fn handle_hello_world(_req: Request) -> Result<impl IntoResponse> {
+    // Create the outbound request object
+    let req = Request::builder()
+        .method(Method::Get)
+        .uri("https://random-data-api.fermyon.app/animals/json")
+        .build();
 
-    res.headers_mut()
-        .insert(http::header::SERVER, "spin/0.1.0".try_into()?);
+    // Send the request and await the response
+    let res: Response = spin_sdk::http::send(req).await?;
 
+    println!("{:?}", res);  // log the response
     Ok(res)
 }
-
 ```
 
-In order for the component above to be allowed to make the outbound HTTP
-request, the destination host must be declared in the Spin application
-configuration:
+For the component above to be allowed to make the outbound HTTP request, the destination host must be declared, using the `allowed_outbound_hosts` configuration, in the Spin application's manifest (the `spin.toml` file):
 
 ```toml
-[[component]]
-id = "hello"
-source = "target/wasm32-wasi/release/spinhelloworld.wasm"
-allowed_outbound_hosts = [ "https://fermyon.com" ]
-[component.trigger]
-route = "/hello"
+spin_manifest_version = 2
+
+[application]
+name = "hello_world"
+version = "0.1.0"
+authors = ["Your Name <your-name@example.com>"]
+description = "An example application"
+
+[[trigger.http]]
+route = "/..."
+component = "hello-world"
+
+[component.hello-world]
+source = "target/wasm32-wasi/release/hello_world.wasm"
+allowed_outbound_hosts = ["https://random-data-api.fermyon.app"]
+[component.hello-world.build]
+command = "cargo build --target wasm32-wasi --release"
+watch = ["src/**/*.rs", "Cargo.toml"]
 ```
 
-Making a request to this component, we can see the appended header, and that the
-response contains the expected body:
+## Building and Running the Spin Application
+
+Spin build can be used to build all components defined in the Spin manifest file at the same time, and also has a flag that starts the application after finishing the compilation, `spin build --up`:
+
+```bash
+$ spin build --up
+Building component hello-world with `cargo build --target wasm32-wasi --release`
+    Finished release [optimized] target(s) in 0.12s
+Finished building all Spin components
+Logging component stdio to ".spin/logs/"
 
+Serving http://127.0.0.1:3000
+Available Routes:
+  hello-world: http://127.0.0.1:3000 (wildcard)
 ```
-$ curl -I localhost:3000/hello
+
+Once our application is running, we can make a request (by visiting `http://localhost:3000/` in a web browser) or using `curl` as shown below:
+
+```bash
+$ curl -i localhost:3000
 HTTP/1.1 200 OK
-content-length: 29350
-content-type: text/html; charset=utf-8
-server: spin/0.1.0
+content-length: 77
+content-type: application/json
+
+{"timestamp":1702599575198,"fact":"Sharks lay the biggest eggs in the world"}
 ```