ROS - Linear Actuators

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ROS seems to have a library for servos but how would I control a Linear Actuator?

From this tutorial
http://learn.robotgeek.com/demo-code/...

It looks like an arduino can control an actuator with the use of push buttons, but how would i get feedback and signals to and from ROS, replacing push buttons with commands?

/* Linear Actuator Control using preset position

This demo shows how to do basic control of a large linear
actuator using an Arduino and two buttons. Each button is hard
coded with a preset position. Pressing a button will move
the actuator to that position.

 The circuit:
 * RobotGeek Pushbutton - Digital Pin 1
 * RobotGeek Pushbutton - Digital Pin 2
 * RobotGeek Relay - Digital Pin 4 
 * RobotGeek Relay - Digital Pin 7 

Products Used in this demo:
 - http://www.robotgeek.com/linear-actuators
 - http://www.robotgeek.com/robotgeek-geekduino-sensor-kit
 - http://www.robotgeek.com/robotGeek-pushbutton
 - http://www.robotgeek.com/robotgeek-relay

 */

// constants won't change. They're used here to set pin numbers:
const int button1Pin = 2;     // the number of the pushbutton1 pin
const int button2Pin = 4;     // the number of the pushbutton2 pin
const int relay1Pin =  7;      // the number of the Realy1 pin
const int relay2Pin =  8;      // the number of the Relay2 pin
const int sensorPin = 0;    // select the input pin for the potentiometer

// variables will change:
int button1State = 0;         // variable for reading the pushbutton status
int button2State = 0;         // variable for reading the pushbutton status
int sensorValue = 0;  // variable to store the value coming from the sensor

int goalPosition = 350; 
int CurrentPosition = 0; 
boolean Extending = false;
boolean Retracting = false;

void setup() {


        //start serial connection
        Serial.begin(9600);

        // initialize the pushbutton pin as an input:
        pinMode(button1Pin, INPUT);     
        pinMode(button2Pin, INPUT);    
        // initialize the relay pin as an output:
        pinMode(relay1Pin, OUTPUT);    
        pinMode(relay2Pin, OUTPUT);    

        //preset the relays to LOW
        digitalWrite(relay1Pin, LOW); 
        digitalWrite(relay2Pin, LOW); 


}

void loop(){

        // read the value from the sensor:
        CurrentPosition = analogRead(sensorPin); 


        // print the results to the serial monitor:
        Serial.print("Current = " );                       
        Serial.print(CurrentPosition);      
        Serial.print("\t Goal = ");      
        Serial.println(goalPosition);  

        // read the state of the pushbutton values:
        button1State = digitalRead(button1Pin);
        button2State = digitalRead(button2Pin);

        if (button1State == HIGH) {     
                // set new goal position
                goalPosition = 300; 

                if (goalPosition > CurrentPosition) {
                                Retracting = false;
                                Extending = true;
                                digitalWrite(relay1Pin, HIGH);  
                                digitalWrite(relay2Pin, LOW);  
                                Serial.println("Extending");     
                }      
                else if (goalPosition < CurrentPosition) {
                                Retracting = true;
                                Extending = false;
                                digitalWrite(relay1Pin, LOW);  
                                digitalWrite(relay2Pin, HIGH); 
                                Serial.println("Retracting");         
                }  
        }

        if (button2State == HIGH) {     
                // set new goal position
                goalPosition = 500; 

                if (goalPosition > CurrentPosition) {
                                Retracting = false;
                                Extending = true;
                                digitalWrite(relay1Pin, HIGH);  
                                digitalWrite(relay2Pin, LOW);  
                                Serial.println("Extending");   
                }        
                else if (goalPosition < CurrentPosition) {
                                Retracting = true;
                                Extending = false;
                                digitalWrite(relay1Pin, LOW);  
                                digitalWrite(relay2Pin, HIGH); 
                                Serial.println("Retracting");         
                }  
        }



        if (Extending = true && CurrentPosition > goalPosition) {
                //we have reached our goal, shut the relay off
                digitalWrite(relay1Pin, LOW); 
                boolean Extending = false; 
                Serial.println("IDLE");  
        }

        if (Retracting = true && CurrentPosition < goalPosition){
                //we have reached our goal, shut the relay off
                digitalWrite(relay2Pin, LOW); 
                boolean Retracting = false; 
                Serial.println("IDLE");  
        }




}