Re: [Rd] Utilizing the internet module

From: Prof Brian Ripley <>
Date: Fri 24 Feb 2006 - 07:13:33 GMT

On Thu, 23 Feb 2006, Jeffrey Horner wrote:

> Prof Brian Ripley wrote:
>> On Thu, 23 Feb 2006, Jeffrey Horner wrote:
>>> Hello all,
>>> I'd like to utilize the R_Sock* functions from R_ext/R-ftp-http.h in my
>>> R package. The intent is to use these in conjunction with R_serialize()
>>> to store R objects in a remote data store. I'm aware that version
>>> 2.2.1 of "Writing R extensions" explains that these may be undocumented
>>> and unstable, but I have a couple of questions:
>>> 1) are they platform independent? I presume they are...
>> Only in sense that they have a common interface.
>>> 2) What's the appropriate way to link against them? On Linux x86, I can
>>> do this with the Makevars:
>> You can, but that is a module and not a library and so it does not work on
>> MacOS X and may well not work on Windows (you would be lucky prior to R
>> 2.3.0).
>> I wonder why you need a C interface at all. There is serialize() and
>> socket connections are available at R level. Below that, Rsockopen etc are
>> exported from R itself and underly make.socket etc.
> I may not need it (or get to use it portably), but as far as using Rsockopen,
> etc. am I right in assuming that a package writer would have to copy the
> declarations from src/main/basedecl.h into his/her own code in order to
> utilize them? This seems odd when there's already an exposed (although
> undocumented) interface with R_Sock*, so what's the point of having
> R_ext/R-ftp-http.h? Is it just for some xml package?

Yes. It was written as an internal header. As you have discovered, the interface is not actually exposed.

> On a related note, how do I serialize() an R object to a database table
> column of type BLOB? I've tried using RODBC but was unsuccessfully (see
> R-sig-DB in Feb archive). I've also looked into RMySQL/DBI but I don't think
> it's supported yet.

Since BLOB is not a standard SQL type (AFAIK), ODBC seems not to support it.

Brian D. Ripley,        
Professor of Applied Statistics,
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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