Chapter 10.2: HTTP Transport (Client)

PMCP’s HTTP transport is a client-side implementation that sends JSON-RPC requests over HTTP and can optionally subscribe to Server-Sent Events (SSE) for notifications. For server deployments, see Streamable HTTP in Chapter 10.3.

When to Use HTTP Transport

• Simple request/response interactions against an HTTP MCP endpoint
• Optional SSE notifications via a separate endpoint
• Firewall-friendly and proxy-compatible

If you control the server, prefer Streamable HTTP (single endpoint with JSON and SSE, plus session support).

Features and Types

• HttpTransport, HttpConfig (feature: http)
• Optional connection pooling and configurable timeouts
• Optional sse_endpoint for notifications

Basic Client Example

use pmcp::{Client, ClientCapabilities, HttpTransport, HttpConfig};
use url::Url;

#[tokio::main]
async fn main() -> pmcp::Result<()> {
    // Create HTTP transport
    let transport = HttpTransport::with_url(Url::parse("http://localhost:8080")?)?;

    // Optionally connect to SSE notifications if your server exposes one
    // transport.connect_sse().await?;

    // Build client and initialize
    let mut client = Client::new(transport);
    let _info = client.initialize(ClientCapabilities::minimal()).await?;

    // Use the client as usual (list tools, call tools, etc.)
    Ok(())
}

Configuration

#![allow(unused)]
fn main() {
use pmcp::HttpConfig;
use url::Url;
use std::time::Duration;

let cfg = HttpConfig {
    base_url: Url::parse("https://api.example.com/mcp")?,
    sse_endpoint: Some("/events".into()), // or None if not using SSE
    timeout: Duration::from_secs(30),
    headers: vec![("Authorization".into(), "Bearer <token>".into())],
    enable_pooling: true,
    max_idle_per_host: 10,
};
}

Feature Flags

[dependencies]
pmcp = { version = "1.7", features = ["http"] }

Notes

• This client can target generic HTTP-style MCP servers.
• For PMCP’s recommended server implementation, see Streamable HTTP (Axum-based) in Chapter 10.3.