Asynchronous Programming

Ambiorix supports asynchronous programming so requests do not block R's single thread, allowing the server to serve other requests in the meantime. This is done by having the handler return a promise: this promise should output a valid response.

Example

The application below demonstrates asynchronous programming and its benefit. One can visit /async then /sync and get a response on the latter, despite the fact that /async is still processing (Sys.sleep(10) = 10 seconds). Were /async not returning a promise, /sync would have to wait until /async had stopped processing (10 seconds) before the server could return a response.

library(future)
library(ambiorix)

plan(multisession)

app <- Ambiorix$new()

app$get("/async", \(req, res){
  future({
    Sys.sleep(10)
    res$send(Sys.time())
  })
})

app$get("/sync", \(req, res){
  res$send(Sys.time())
})

app$start()