Non blocking worker servlet ?

Question

Hi friends,
I have an issue to implement. We implemented a web application and now I want to separate some parts of this application. I can express the action shorter and simple below.
if a user requests x-y ticket {
���try {
������check db if x-y is available
������if true send available
������else not
���}catch (NonExistentData) {
������addJob2Queue(x-y)
������send available
���}
class AvailabilityHelper extends Thread{
���run(){
������while(true){
���������checkQueue
���������if there is job, updateDBfor(org,dest)
������}
���}
* updateDBfor(org,dest) includes other ejb references to request data and insert it into db
This web aplication runs with JSP 1.2 EL support on WAS 5.1
the check for db and the thread implementation was in a seperate package and were used in actions of web application. Now they also want to use these checks for other (non web) applications. So i think there should be a session bean in ejb and should process these requests and I used JMS (Message-Driven Bean) with WebSphere MQ to undertake the thread and queue mechanism.
Now it works like this :
class exampleSessionBean{
���getAvalibability(org, dest){
������try {
���������check db if x-y is available
���������if true send available
���������else not
������}catch (NonExistentData) {
���������queueSender.sendMessage(update x-y)
���������send available;
������}
���}
class queueMDB{
���onMessage(){
������updateDBfor(org,dest)
���}
The purpose of this applications was, not to block the user for db update process, if there is data in db select and show to the user. the update process of db includes other ejb references and takes so much time. It is nonsense to make the user wait such time. And the info is not a big deal, because of this when i put a request for update, without blocking i send it as available...
So what is the problem ? :) Deployment team don't want to pay for websphere MQ and hire a admin for that. Also they don't want to use Embedded Messaging server client (JMS Server) of WAS. So I am asking you: is there a way to implement a non blocking servlet so that i will just make a request and don't wait for response, or a servlet will take the request and release the connection but will continue to process the request ?
thanks for all...

Answer 1

I tried to implement a web application and add a ServletContextListener as stevejluke suggests. But on contextInitialized function when creating new JobConsumer it gets following errors on server.
6/27/06 12:51:36:391 CEST] 33238138 WebContainer A SRVE0169I: Loading Web Module: non-blocking.
[6/27/06 12:51:36:438 CEST] 33238138 SystemOut O OlaListener initializing...
[6/27/06 12:51:36:516 CEST] 33238138 SystemOut O OlaListener - Queue added
[6/27/06 12:51:36:516 CEST] 33238138 SystemOut O OlaListener - keepWorking
[6/27/06 12:51:36:672 CEST] 33238138 WebApp E SRVE0015E: Failure to initialize Web application non-blocking
[6/27/06 12:51:36:844 CEST] 33238138 WebGroup E SRVE0054E: An error occurred while loading Web application
public class OlaListener implements ServletContextListener {
     * @see javax.servlet.ServletContextListener#void (javax.servlet.ServletContextEvent)
     public void contextDestroyed(ServletContextEvent event) {
             ServletContext context = event.getServletContext();
             context.setAttribute("keepWorking", Boolean.FALSE);
     * @see javax.servlet.ServletContextListener#void (javax.servlet.ServletContextEvent)
     public void contextInitialized(ServletContextEvent event) {
             System.out.println("OlaListener initializing...");
             ServletContext context = event.getServletContext();
             WorkQueue newJobs = new WorkQueue();
             context.setAttribute("newJobs", newJobs);
             System.out.println("OlaListener - Queue added");
             context.setAttribute("keepWorking", Boolean.TRUE);
             System.out.println("OlaListener - keepWorking");
             JobConsumer jc = new JobConsumer();
             System.out.println("OlaListener - Job Consumer created");
             jc.setContext(context);
             System.out.println("OlaListener - context set");
             Thread t = new Thread(jc);
             t.start();
public class JobConsumer implements Runnable{
     /*log4j*/     private static final Logger logger = Logger.getLogger(JobConsumer.class);     
     private ServletContext context = null;
     public void run(){
             System.out.println("JobConsumer - run Start");
             processQueue(context);
             System.out.println("JobConsumer - run End");
}