Learn WASMCLOUD with Real Code Examples

Updated Nov 25, 2025

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Code Sample Descriptions

Simple wasmCloud Actor (Rust)

# wasmcloud/demo/src/lib.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().body("Hello, wasmCloud!"))
}

A basic wasmCloud actor written in Rust that responds with 'Hello, wasmCloud!' when invoked.

Let’s Try →

wasmCloud Actor Returning JSON

# wasmcloud/demo/json.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;
use serde_json::json;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let body = json!({"message": "Hello JSON!"}).to_string();
    Ok(Response::ok().body(&body).with_header("Content-Type", "application/json"))
}

Responds with JSON data from a wasmCloud actor.

Let’s Try →

wasmCloud Actor Reading Query Params

# wasmcloud/demo/query.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    let query = req.query_params.get("name").unwrap_or(&"Guest".to_string());
    Ok(Response::ok().body(format!("Hello, {}!", query)))
}

Reads query parameters from the request.

Let’s Try →

wasmCloud Actor Handling POST

# wasmcloud/demo/post.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    if req.method == "POST" {
        Ok(Response::ok().body(req.body))
    } else {
        Ok(Response::ok().status(405).body("Method Not Allowed"))
    }
}

Handles POST requests and echoes JSON body.

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wasmCloud Actor with Custom Header

# wasmcloud/demo/header.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().body("Custom Header Added").with_header("X-Custom", "wasmCloud"))
}

Adds a custom header to the response.

Let’s Try →

wasmCloud Actor Redirect

# wasmcloud/demo/redirect.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().status(302).with_header("Location", "https://example.com"))
}

Redirects request to another URL.

Let’s Try →

wasmCloud Actor Calling External API

# wasmcloud/demo/fetch.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;
use reqwest;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let res = reqwest::blocking::get("https://api.github.com")?.text()?;
    Ok(Response::ok().body(res))
}

Fetches data from an external API and returns it.

Let’s Try →

wasmCloud Actor Conditional Response

# wasmcloud/demo/conditional.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    if req.query_params.get("action") == Some(&"ping".to_string()) {
        Ok(Response::ok().body("pong"))
    } else {
        Ok(Response::ok().body("unknown action"))
    }
}

Responds differently based on query parameter.

Let’s Try →

wasmCloud Actor Using Environment Variable

# wasmcloud/demo/env.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let key = std::env::var("MY_API_KEY").unwrap_or("NotSet".to_string());
    Ok(Response::ok().body(format!("API Key length: {}", key.len())))
}

Uses an environment variable to customize response.

Let’s Try →

wasmCloud Actor Returning HTML

# wasmcloud/demo/html.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let html = "<!DOCTYPE html><html><body><h1>Hello, wasmCloud!</h1></body></html>";
    Ok(Response::ok().body(html).with_header("Content-Type", "text/html"))
}

Returns a simple HTML page from an actor.

Let’s Try →

Code Sample Descriptions

Simple wasmCloud Actor (Rust)

# wasmcloud/demo/src/lib.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().body("Hello, wasmCloud!"))
}

A basic wasmCloud actor written in Rust that responds with 'Hello, wasmCloud!' when invoked.

Let’s Try →

wasmCloud Actor Returning JSON

# wasmcloud/demo/json.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;
use serde_json::json;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let body = json!({"message": "Hello JSON!"}).to_string();
    Ok(Response::ok().body(&body).with_header("Content-Type", "application/json"))
}

Responds with JSON data from a wasmCloud actor.

Let’s Try →

wasmCloud Actor Reading Query Params

# wasmcloud/demo/query.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    let query = req.query_params.get("name").unwrap_or(&"Guest".to_string());
    Ok(Response::ok().body(format!("Hello, {}!", query)))
}

Reads query parameters from the request.

Let’s Try →

wasmCloud Actor Handling POST

# wasmcloud/demo/post.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    if req.method == "POST" {
        Ok(Response::ok().body(req.body))
    } else {
        Ok(Response::ok().status(405).body("Method Not Allowed"))
    }
}

Handles POST requests and echoes JSON body.

Let’s Try →

wasmCloud Actor with Custom Header

# wasmcloud/demo/header.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().body("Custom Header Added").with_header("X-Custom", "wasmCloud"))
}

Adds a custom header to the response.

Let’s Try →

wasmCloud Actor Redirect

# wasmcloud/demo/redirect.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    Ok(Response::ok().status(302).with_header("Location", "https://example.com"))
}

Redirects request to another URL.

Let’s Try →

wasmCloud Actor Calling External API

# wasmcloud/demo/fetch.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;
use reqwest;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let res = reqwest::blocking::get("https://api.github.com")?.text()?;
    Ok(Response::ok().body(res))
}

Fetches data from an external API and returns it.

Let’s Try →

wasmCloud Actor Conditional Response

# wasmcloud/demo/conditional.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(req: Request) -> HandlerResult<Response> {
    if req.query_params.get("action") == Some(&"ping".to_string()) {
        Ok(Response::ok().body("pong"))
    } else {
        Ok(Response::ok().body("unknown action"))
    }
}

Responds differently based on query parameter.

Let’s Try →

wasmCloud Actor Using Environment Variable

# wasmcloud/demo/env.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let key = std::env::var("MY_API_KEY").unwrap_or("NotSet".to_string());
    Ok(Response::ok().body(format!("API Key length: {}", key.len())))
}

Uses an environment variable to customize response.

Let’s Try →

wasmCloud Actor Returning HTML

# wasmcloud/demo/html.rs
use wasmcloud_actor_core::prelude::*;
use wasmcloud_actor_http_server::prelude::*;

#[actor::init]
pub fn init() {}

#[actor::handler]
pub fn handle(_req: Request) -> HandlerResult<Response> {
    let html = "<!DOCTYPE html><html><body><h1>Hello, wasmCloud!</h1></body></html>";
    Ok(Response::ok().body(html).with_header("Content-Type", "text/html"))
}

Returns a simple HTML page from an actor.

Let’s Try →