Question

Our page has a datatable which shows records from a web service. The web service queries a database, and the query can take from 10 secs to 100 secs.

I was initially loading the arraylist binded to the datatable in the backing bean constructor:

private ArrayList myList;
public MyBean
{
     myList = WebServices.getList();
}

In this scenario, the entire page starts to render only after the web service returns all data.

Where should I call the webservice (i.e., do myList = WebServices.getList(); ) in order to have the rest of the page load in parallel, and show a progress bar or something in the datatable while the webservice runs?

I guess my concepts about the JSF/IceFaces lifecycle are not clear…

Also, this is not about lazy loading, because for that we would have to implement pagination in our datatabase query, too.

Thanks!

Answer 1

I found a work around using Threads.

public class MyBean
{
    private ArrayList myList;
    private PersistentFacesState state;

    public MyBean
    {
        state = PersistentFacesState.getInstance();
        myList = new ArrayList();
        new Thread(new RunService()).start();
    }

    public class RunService implements Runnable
    {
        public void run()
        {
            try
            {
                list = WebServices.getList();
                state.executeAndRender(); //Need to do this to update view

            }
            catch(Exception e)
            {

            }
        }

    }
}

Initally I was not aware of the PersistentFacesState and executeAndRender(); , so even though the thread would update the array list, the view wasn’t being refreshed. This was because the JSF/IceFaces lifecycle had already ended.

Persisting the view and then re-rendering it solved this problem, too.

Hope this solution helps someone.