The R/Apache Integration Project
Presented at the Directions in Statistical Computing Conference
DSC2005 paper and
presentation.
The Latest Release is 0.1.4
What is it?
R/Apache is a project dedicated to embedding the R interpreter inside the Apache 2.0 (and beyond) web server. It's composed of three parts:
mod_R: the Apache 2.0 module that implements the glue to load the
R interpreter.
RApache: the R package that provides the API for programming web
applications in R.
libapreq 2.0.4: an Apache sponsored project for parsing request input.
If you don't want to compile and install this version, then you can
specify which libapreq2 library to use during configuration.
Prerequisites
This release has been tested under Debian Linux with Apache 2.0.55,
R 2.3.1, and libapreq 2.0.4. Apache2
MUST be compiled with the
prefork MPM to compile mod_R. Also, R must have been compiled with
the --enable-R-shlib configure flag.
Installation
The following is the preferred way to compile and install mod_R:
$ ./configure --with-apache2-apxs=/path/to/apxs --with-R=/path/to/R
$ make
$ make install
Both --with-apache2-apxs and --with-R
MUST be specified. Otherwise,
trying to figure out the dependencies between the sources and headers
and library paths becomes quite complex.
If you don't want to compile and install the bundled libapreq2 version,
then add --with-apreq2-config=/path/to/apreq2-config. The version
MUST
be equal to or greater than 2.0.4.
Configuration
In order to use mod_R and RApache, you must configure apache to find
it. Type help("directives",package="RApache") once mod_R is installed
for a little more detail. Add something similar to this to the apache
config file:
LoadModule R_module /path/to/mod_R.so
<Location /URL>
SetHandler r-handler
Rsource /path/to/R/code.R
RreqHandler function-name
Rlibrary library-name
</Location>
Also, libR.so
MUST be found in the shared library path as it is
linked to by mod_R, RApache and the rest of the packages containing
shared libraries. You can either set LD_LIBRARY_PATH like this:
$ export LD_LIBRARY_PATH=`/path/to/R RHOME`/lib
or add that path to /etc/ld.so.conf and then run ldconfig.
NOTE: the latest apache2 debian packages cause the web server to run
in a very reduced environment, thus one is unable to set LD_LIBRARY_PATH
before calling /etc/init.d/apache2. One option is to actually edit that
file and add the LD_LIBRARY_PATH explicitly. Another is to use the apache2ctl
scripts which are also bundled with the debian packages. Or you can add it
to /etc/ld.so.conf.
Documentation
All of the documentation is currently in the RApache package. Once
you install mod_R, start R and load the RApache package. You'll get
a warning that you're currently not running the R interpreter within
Apache; just don't try to run any of the code. Sample session:
> library(RApache)
Warning message:
RApache is only useful within the Apache web server.
It is loaded now for informational purposes only
in: firstlib(which.lib.loc, package)
> help(package="RApache")
Information on package 'RApache'
Description:
Package: RApache
Version: 0.1-1
Date: 2005-08-02
Title: An R interface to the Apache 2.0 web server
Author: Jeffrey Horner
Maintainer: Jeffrey Horner <jeff.horner@vanderbilt.edu>
License: Apache License, Version 2.0
Description: RApache allows web applications to be written in R and
executed within the Apache 2.0 web server.
Built: R 2.1.0; i386-pc-linux-gnu; 2005-08-02 01:06:26; unix
Index:
IO IO in RApache
apache.add_cookie Adding Cookies to Outgoing Headers
apache.add_header Adding HTTP headers
apache.allow_methods RApache Methods
apache.log_error Logging Errors to the Apache error log
apache.set_content_type
Setting the Content Type header
apr_table Structure of the apr_table type in RApache
as.html Converting RApache objects to HTML
directives RApache directives used in Apace config file
intro Introduction to RApache
request_rec Structure of the RApache request record
return_codes RApache handler return codes
Licensing
The R/Apache source code is licensed under the Apache License Version
2.0. Please see the file called LICENSE in the source distribution.
Changes
Changes in 0.1.4
*) Added apache.encode() and apache.decode() for en(de)coding html
entities
*) R now uses Apache's tmp dir
Changes in 0.1.3
*) Now plays nicely with mod_cgi (thanks to Jeremy Stephens).
Apache runs cleanup code per-child after a fork and before
executing cgi scripts. This was not handled properly, and R/Apache
caused the child to segfault.
Changes in 0.1.2
*) Libraries and source files (specified with Rlibrary and Rsource
in the apache config) are now loaded only once (thanks to Jeremy
Stephens).
*) Added mod_R version component to Apache response headers
Changes in 0.1.1
*) Fixed spelling of R_module (thanks to Kevin E. Thorpe) in README
and RApache/man/directives.Rd.
*) Fixed compile error on Mac OS X (thanks to Jan de Leeuw).
*) Fixed bug in as.list.apr_table (thanks to Gregoire Thomas) and
subsequently in as.list.ra_request_rec
Miscellaneous Files
to top
