/**A servlet demonstrating the Client Pull technique.
* Internet Programming 2 - Course
* @author Martin Carlsson
*/
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.*;
import java.awt.image.*;
import java.util.*;
import com.sun.image.codec.jpeg.JPEGCodec;
import java.text.*;


public class ClientPull extends HttpServlet {
    
    private int yPos = 40, xPos = 40, TEXT_SIZE = 24;
        
    
    public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException {

        System.setProperty("java.awt.headless", "true");
        BufferedImage buffImg = new BufferedImage(400,TEXT_SIZE*2,BufferedImage.TYPE_INT_RGB);  
        Graphics2D g = buffImg.createGraphics();
        g.setFont(new Font("Serif", Font.ITALIC,TEXT_SIZE)); 
        g.setColor(Color.RED);
        DateFormat f = DateFormat.getTimeInstance();
        g.drawString("Dynamic clock using client pull",xPos,yPos/2);
        g.setColor(Color.GREEN);        
        g.drawString(f.format(new Date()),xPos*3,yPos);
        // Encodes and sends the buffered image
        res.setHeader("Refresh","1");// The client/browser will pull/request the this servlet every second
        ServletOutputStream sOs = res.getOutputStream();
        res.setContentType("image/jpeg");
        JPEGCodec.createJPEGEncoder(sOs).encode(buffImg);
        sOs.flush();
        sOs.close();
    }
}// End class ClientPull