How to run an application on another port from within MODX?

A question about ports and users on linux..

I use a statistical language called R to run analyses and create plots and charts. R runs on port 8787. For the purposes of this test I have installed R under root.

I want to use MODX to run R scripts and output the results in my MODX-served web pages. MODX is installed in the usual way, with the manager on port 8443.

I want to be able to write and save R scripts as resources in MODX, possibly using the template to direct the script to R for processing, with the output returned to MODX for display.

Can anyone advise me on whether this sounds feasible and, if so, what I need to know/do in order to do it?

Centos 7
MODX Revolution 2.5.7-pl
R version 3.4.1 (2017-06-30). Platform: x86_64-redhat-linux-gnu (64-bit)

OK, maybe I should generalise this question a bit.

MODX accesses MySQL, which runs on port 3306.

Are there any standard methods available in MODX to access other services which run on different ports on the same server?

Hmmm, how do I find info on ports in the docs?...

MODX Documentation
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I wonder if it is correct to think in terms of accessing R via a port number?

Should you instead be using php to run R scripts using local paths, having defined where your R binary lives on the server?

This conversation on StackExchange might help (or be completely off topic)!

https://stats.stackexchange.com/questions/4279/how-can-i-integrate-r-with-php