capnweb-server

Production-ready server for Cap'n Web RPC protocol with capability management.

Overview

capnweb-server provides a high-performance, production-ready server implementation of the Cap'n Web RPC protocol. It supports multiple transport layers and includes built-in capability management, rate limiting, and observability.

Features

• Multiple transports: HTTP batch, WebSocket, and WebTransport support
• Capability management: Register and manage RPC capabilities
• Rate limiting: Built-in rate limiting and DOS protection
• Session management: Automatic session tracking and cleanup
• Observability: Structured logging and metrics
• Type-safe handlers: Async trait-based RPC target implementation

Quick Start

Add to your Cargo.toml:

[dependencies]
capnweb-server = "0.1.0"

Create a simple server:

use capnweb_server::{Server, ServerConfig, RpcTarget};
use capnweb_core::{CapId, RpcError};
use async_trait::async_trait;
use serde_json::{json, Value};
use std::sync::Arc;
use anyhow::Result;

#[derive(Debug)]
struct MyService;

#[async_trait]
impl RpcTarget for MyService {
    async fn call(&self, method: &str, args: Vec<Value>) -> Result<Value, RpcError> {
        match method {
            "echo" => Ok(json!({ "echoed": args })),
            _ => Err(RpcError::not_found("Method not found")),
        }
    }
}

#[tokio::main]
async fn main() -> Result<()> {
    let config = ServerConfig {
        port: 8080,
        host: "127.0.0.1".to_string(),
        max_batch_size: 100,
    };

    let server = Server::new(config);
    server.register_capability(CapId::new(0), Arc::new(MyService));

    server.run().await?;
    Ok(())
}

Binary

The crate includes a capnweb-server binary for quick testing:

cargo install capnweb-server
capnweb-server

Configuration

The server can be configured via ServerConfig:

• port: Server port (default: 8080)
• host: Bind address (default: "127.0.0.1")
• max_batch_size: Maximum batch request size
• rate_limit: Requests per second limit
• session_timeout: Session inactivity timeout

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.