package de.mxro.webapiexample.internal.services;
   
   import java.io.IOException;
   
   import javax.servlet.ServletException;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
  
  /**
   * <p>This service can be used to check if the server can be reached.
   * <p>Upon a GET request, it will return a JSON document which reports the status of the server.
   * <p>Upon a HEAD request, it will return the status 200.
   * 
   * @author Max
   *
   */
  public class HealthServlet extends HttpServlet {
  
  	private static final long serialVersionUID = 1L;
  
  	/**
  	 * The time when this servlet was initialized.
  	 */
  	private long serverStartedAt;
  	
  	@Override
  	protected void doHead(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  		response.setStatus(HttpServletResponse.SC_OK);
  	}
  
  	@Override
  	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  		assert serverStartedAt != -1;
  		
  		response.setContentType("application/json");
  		response.setStatus(HttpServletResponse.SC_OK);
  		response.getWriter().println("{ \"running\": true}");
  		
  	}
  
  	
  	
  	@Override
  	public void init() throws ServletException {
  		serverStartedAt = System.currentTimeMillis();
  	}
  
  	public HealthServlet() {
  		super();
  		serverStartedAt = -1;
  	}
  	
  	
  	
  	
  	
  }