Exposing R-script as API

R is getting popular programming language in the area of Data Science. Integrating Rscript with web UI pages is a challenge which many application developers are facing. In this blog post I will explain how we can expose R script as an API, using rApache and Apache webserver.

rApache is a project supporting web application development using the R statistical language and environmentand the Apache web server.

Exposing Rscipt as API typically involves 3 steps:

1. Pre-requisites
2. Installing rApache
3. Configuring rApache

Step #1 - Pre_requisites :

• Linux environment - ubuntu
• latest version of R - R- 3.1.0

Step#2 - Install apache webserver as below:

apt-get install r-base-dev apache2-mpm-prefork apache2-prefork-dev
wget http://www.rapache.net/rapache-1.2.3.tar.gz
 tarxzvf rapache-1.2.3.tar.gz
cd rapache-1.2.3
 ./configure
 make
make install

Step#3: Configuring rApache.

• Once rApache is installed, start the rApache server as below:

service apache2 start


• Since we are installing for the first time let us test if the setup is installed properly. Do the below steps.

sudo vim /etc/apache2/apache2.conf #Added the following:




• Once you have done the above step, Now access the below pages:

IPAddress/html/index.html





IPAddress/RApacheInfo.html




• Before getting into expose R-script as API let us understand the rApache configuration.
  Once the rApache is installed the folder structure of rApache would be as below:



• In apache2.conf file, we need to configure all the sites/r-scripts that we need to expose as api.. Below we have set a directory at path “/var/www/RProject“ in directory tags in apache2.conf file.





• Now place the below R-script (test.r) generating a random normal distribution in the RProject folder specified above,in the code belowGET$p is input parameter we pass from URL.





• The api is ready for testing.We can access the api using IP.XXX.XXX.XXX/RProject/test.r?q=10 And the results would be as below:

• Detailed documentation of Installation is found here