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Improve your REST Webservice response time using java.util.TimerTask

A while ago, I built an MAF application, which was consuming a few REST webservices from Oracle Java Cloud. But for each request from the app, the response JSON was getting created, and which made the app response very slow. 
So, I created the contents of the REST response as a scheduled job. My data wasn't getting changed that often, so I choose to build my REST responses every morning at 10am using java.util.TimerTask.

Used Software: JDeveloper 12.1.3

#1. REST response POJOs :
public class Feed {
   
    public String url;
    public String source;
   
    public Feed() {
        super();
    }
   
    public Feed(String source, String url) {
        setSource(source);
        setUrl(url);
    }
   
    public void setSource(String source) {
        this.source = source;
    }

    public String getSource() {
        return source;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUrl() {
        return url;
    }
}


================================

@XmlRootElement(name = "feeds")
public class FeedsArray {

    private List<Feed> feeds;

    public void setFeeds(List<Feed> feeds) {
        this.feeds = feeds;
    }

    public List<Feed> getFeeds() {
        return feeds;
    }
}


#2. TimerTask class :
You need to create a class which extends java.util.TimerTask and override run() to put your custom code.
I have used a Singleton object (Feeds) to create and store my response.

public class FeedRSSScheduler extends TimerTask {
    public FeedRSSScheduler() {
        super();
    }

    @Override
    public void run() {
        Feeds.getInstance().buildFeedsMap();
    }
}


============================

public class Feeds {
   
    private static Feeds instance = null;
   
    private FeedsArray feedsArray;
   
    protected Feeds() {
        super();
    }
   
    public static Feeds getInstance() {
      if(instance == null) {
         instance = new Feeds();
      }
      return instance;
    }


    public FeedsArray getFeedsArray() {
        if(feedsArray == null) {
            buildFeedsMap();
        }
        return feedsArray;
    }
   
    public void buildFeedsMap() {
        // PUT your custom code here to populate the FeedsArray object

    }
}


#3. Servlet container class :
 
public class JobSchedulerServlet extends ServletContainer {
   
    private final static long ONCE_PER_DAY = 1000*60*60*24;
    private final static int TEN_AM = 10;
    private final static int ZERO_MINUTES = 0;
   
    public JobSchedulerServlet(Application application) {
        super(application);
    }

    @Override
    public void init() throws ServletException {   
        startFeedRSSTask();
        super.init();
    }

    public JobSchedulerServlet(Class<? extends Application> class1) {
        super(class1);
    }

    public JobSchedulerServlet() {
        super();
    }
   
    private Date getTomorrowMorning10AM(){
        Date date2am = new Date();
        date2am.setHours(TEN_AM);
        date2am.setMinutes(ZERO_MINUTES);
        return date2am;
    }
   
    private void startFeedRSSTask(){
        FeedRSSScheduler feedRSSScheduler = new FeedRSSScheduler();
        Timer timer = new Timer(); 
        timer.schedule(feedRSSScheduler, getTomorrowMorning10AM(), ONCE_PER_DAY);
    }
}


#4. Register your Servlet container class in web.xml :
  <servlet>
    <servlet-name>jersey</servlet-name>
    <servlet-class>rest.scheduler.JobSchedulerServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>jersey</servlet-name>
    <url-pattern>/*</url-pattern>
  </servlet-mapping>


#5. Create REST service :

@Path("/feeds")
public class FeedMap {
   
    @GET
    @Path("/sources")
    @Produces(MediaType.APPLICATION_JSON)
    public FeedsArray getFeedsMap() {
        return Feeds.getInstance().getFeedsArray();
    }
}

/// URL to access this service : http://<server>:<port>/<context_root>/feeds/sources

That's it. When you create and deploy this WAR file, the job will start instantly and then every day morning at 10am.

Comments

  1. TimerTask is old approach, use ScheduledThreadPoolExecutor

    ReplyDelete

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