Re: [Rd] [R] HTTP User-Agent header

From: Henrik Bengtsson <>
Date: Fri 28 Jul 2006 - 19:40:25 GMT

On 7/28/06, Robert Gentleman <> wrote:
> I wonder if it would not be better to make the user agent string
> something that is configurable (at the time R is built) rather than at
> run time. This would make Seth's patch about 1% as long. Or this could
> be handled as an option. The patches are pretty extensive and allow for
> setting the agent header by setting parameters in function calls (eg
> download.files). I am not sure there is a good use case for that level
> of flexibility and the additional code is substantial.
> The issue that I think arises is that there are potentially other
> systems that will be unhappy with R's identification of itself and so
> some users may also need to turn it off.
> Any strong opinions?

Actually two:

  1. If you wish to pull down (read extract from HTML or similar) live data from the web, you might want to be able to "immitate" a certain browser. For instance, if you tell some webserver you're a simple "mobile phone" or "lynx", you might be able get back very clean data. Some servers might also block unknown web browsers.
  2. If the webserver of a package reprocitory decided to make use of the user-agent string to decide what version of the reprocitory it should deliver, I would like to be able to trick the server. Why? Many times I found myself working on a system where I do not have the rights to update to the latest or the developers version of R. However, although I have not the very latest version of R you can do work. For instance, in Bioconductor the biocLite() & co gives you either the stable or the developers of Bioconductor depending on your R version, but looking into the biocLite() code and beyond, you find that you actually can install a Bioconductor v1.9 package in R v2.3.1. It can be risky business, but if you know what you're doing, it can save your day (or week).



> James P. Howard, II wrote:
> > On 7/28/06, Seth Falcon <> wrote:
> >
> >> I have a rough draft patch, see below, that adds a User-Agent header
> >> to HTTP requests made in R via download.file. If there is interest, I
> >> will polish it.
> >
> > It looks right, but I am running under Windows without a compiler.
> >
> --
> Robert Gentleman, PhD
> Program in Computational Biology
> Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N, M2-B876
> PO Box 19024
> Seattle, Washington 98109-1024
> 206-667-7700
> ______________________________________________
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> mailing list Received on Sat Jul 29 05:44:24 2006

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