RESTful R Services

Introduction#

OpenCPU uses standard R packaging to develop, ship and deploy web applications.

opencpu Apps

The official website contain good exemple of apps: https://www.opencpu.org/apps.html

The following code is used to serve a R session:

library(opencpu)
opencpu$start(port = 5936)

After this code is executed, you can use URLs to access the functions of the R session. The result could be XML, html, JSON or some other defined formats.

For exemple, the previous R session can be accessed by a cURL call:

#curl uses http post method for -X POST or -d "arg=value"
curl https://localhost:5936/ocpu/library/MASS/scripts/ch01.R -X POST
curl https://localhost:5936/ocpu/library/stats/R/rnorm -d "n=10&mean=5"

The call is asynchronous, meaning that the R session is not blocked while waiting for the call to finish (contrary to shiny).

The call result is kept in a temporary session stored in /ocpu/tmp/

An exemple of how to retrieve the temporary session:

curl https://public.opencpu.org/ocpu/library/stats/R/rnorm -d n=5
/ocpu/tmp/x009f9e7630/R/.val
/ocpu/tmp/x009f9e7630/stdout
/ocpu/tmp/x009f9e7630/source
/ocpu/tmp/x009f9e7630/console
/ocpu/tmp/x009f9e7630/info

x009f9e7630 is the name of the session.

Pointing to /ocpu/tmp/x009f9e7630/R/.val will return the value resulting of rnorm(5), /ocpu/tmp/x009f9e7630/R/console will return the content of the console of rnorm(5), etc..