civetwebR

An embedded, high-performance HTTP server for R based on the CivetWeb C library.

Key Features

• Thread Safety: Uses a "Pull" model where multi-threaded C (50 worker threads) handles socket I/O and a single R thread processes logic, ensuring the R interpreter never crashes or deadlocks.
• WebSockets: Full support for bi-directional, stateful communication (Open, Message, and Close events).
• Routing: Support for method-based routing and path grouping.
• Static Content: Built-in static file serving with directory listing, breadcrumbs, and security guards.

WebSockets

civetwebR makes it easy to build stateful, reactive applications:

on_ws("open", function(req) {
  message(sprintf("Client %s connected", req$id))
})

on_ws("message", function(req) {
  msg <- rawToChar(req$body)
  ws_send(req$id, paste("Echo:", msg))
})

on_ws("close", function(req) {
  message(sprintf("Client %s disconnected", req$id))
})

• Flexible I/O: Support for custom headers, query parameter parsing, and binary (raw) request/response bodies.
• Interrupt Friendly: Fully supports Ctrl+C to stop the server gracefully from the R console.

Installation

# Install from GitHub
# devtools::install_github("vedoa/civetwebR")

Usage

library(civetwebR)

# Start a server on port 8080
serve(port = 8080, host = "127.0.0.1")

Handlers

handle("GET", "/path", function(req) "ok")

Static Files

Serve files directly from disk:

serve(
  port = 8080,
  static = list(
    list(dir = "public", prefix = "/")
  )
)

Routing Groups

Group routes under a common prefix:

group("/api", {
  handle("GET", "/hello", function(req) "hi")
})

Request

req <- list(
  method = "...",
  path   = "..."
)

Response

Character:

"ok"

→ 200 text/plain

List:

list(
  status = 200L,
  headers = list(),
  body = "data"
)

Notes

• All handlers run in the R thread
• No concurrency in user code

License

MIT