R-integration-with-java

Using Rserve how to make TCP/IP connection to run r code located on remote machine

install Rserve package into Rstudio

install.packages('Rserve')

it will download some java jar in the package directory

directory structure will be soething like C:\Users\username\Documents\R\win-library\3.4\Rserve\java it will contain two jar

• Rengine.jar
• Rserver.jar

create a java Web project in the IDE of your choice ex-eclipse

create project in IDE

select dynamic project

give a project name

copy the R and Java integration jar to the project

copy the jar from the java directory of Rserver package

paste the jar to the Web-lib

the web lib looks like this

create a java class

give class name RIntegration

Methods to invoke

to connect to remote machine

it will take four parameters host machine name,port no default 6312,username,password to connect to the machine in which you want to run R code

public static RConnection connection = null; 
	public static RConnection open(RConnection connection,String hostname,int port,String username,String password) throws RserveException{
        connection = new RConnection(hostname,port);
        connection.login(username,password);
        return connection;
	}

if you want to connect to the same server

	public static RConnection open(RConnection connection) throws RserveException{
		connection = new RConnection();
		return connection;
	}

how to run scripts we need to assign a path like a central repo

to run code on windows it will take four \\ in the path

public static String scriptPAth="put the path which you want to pass";//in the src variable
public static void scriptloading(RConnection connection,String filename) throws RserveException{
		String path= "source('C:\\\\Users\\\\guptakas\\\\Rscripts\\\\"+filename+"')";
		 connection.eval(path);
	}

to run your code you have to define custom methods

here is a function to add

	public static REXP funcall(RConnection connection,String funcname,int num1,int num2) throws RserveException, REXPMismatchException{
		return connection.eval(funcname+"("+num1+","+num2+")");
	}

to close a conection

public static void close(RConnection connection) throws RserveException{
		if(connection !=null){
			connection.close();
		}
	}

to run a code remotely

• Rserve.exe should be running
• to run Rserve.exe library('Rserve') Rserve()
• it will acts as a listner

a method for synchronusly running the scripts

• connect

connection = open(connection,"Ip addres",6311,"username", "password");

• load the scripts it will take scriptname

scriptloading(connection,"add.R");

• contents of add.R similary defines your own mwthod

myAdd=function(x,y){
    sum=x+y
    return(sum)
}

• custom method to run code

int sum=funcall(connection,"myAdd",10,20).asInteger();

• print or return it or consume the way you want

System.out.println("The sum is=" + sum);

the method will look something like this

public static void test1() throws RserveException {
		System.out.println("entering");
	    try {
	        /* Create a connection to Rserve instance running
	         * on default port 6311
	         */
	    	
	        //connection = new RConnection("127.0.0.1",6311);
	        //connection.login("guptakas", "Microfocus@123");
	    	connection = open(connection,"Ip addres",6311,"username", "password");
	    	System.out.println("connection established");
	        /* Note four slashes (\\\\) in the path */
	        scriptloading(connection,"add.R");
	        int sum=funcall(connection,"myAdd",10,20).asInteger();
	        System.out.println("The sum is=" + sum);
	    } catch (RserveException e) {
	        e.printStackTrace();
	    } catch (REXPMismatchException e) {
	        e.printStackTrace();
	    }finally{
	        close(connection);
	        if(connection.isConnected())
	        {
	        	System.out.println("still connected");
	        }
	        System.out.println("connection close");
	    }
	    
	}

create a Rintegration Object and run methods

		RJavaIntegration rconnect = new RJavaIntegration();
		rconnect.test1();