[R] opening URL for writing

[Bierman, Stijn]

Dear List,
 
Sharepoint sites are used more and more often by researchers as a
platform to share all the information in a joint research project.
Typically, they can be accessed only by a Hypertext Transfer Protocol
Secure (HTTPS) URL. 
We are investigating whether it is possible to read and write data to
Microsoft Sharepoint sites using R.
 
We have managed to open a read-only connection to read data from
sharepoint sites using the 'url' function (connections{base}), for
example:
 
conn <- url(description="https://path_to_sharepointsite/data.csv", open
="r);

dat <- read.table(file=conn, sep=",");

However, it appears that URLs can only be opened for reading; from the
connections{base} help file:
"Not all modes are applicable to all connections: for example URLs can
only be opened for reading."
 
Does anyone know how to open a write connection to a microsoft
sharepoint site, or how to open a URL connection for writing?
 
many thanks,
Stijn Bierman