ADF how to display a processing page when executing large queries

Question

ADF how to display a processing page when executing large queries
The ADF application that I have written currently has the following structure:
DataPage (search.jsp) that contains a form that the user enters their search criteria --> forward action (doSearch) --> DataAction (validate) that validates the inputted values --> forward action (success) --> DataAction (performSearch) that has a refresh method dragged on it, and an action that manually sets the itterator for the collection to -1 --> forward action (success) --> DataPage (results.jsp) that displays the results of the then (hopefully) populated collection.
I am not using a database, I am using a java collection to hold the data and the refresh method executes a query against an Autonomy Server that retrieves results in XML format.
The problem that I am experiencing is that sometimes a user may submit a query that is very large and this creates problems because the browser times out whilst waiting for results to be displayed, and as a result a JBO-29000 null pointer error is displayed.
I have previously got round this using Java Servlets where by when a processing servlet is called, it automatically redirects the browser to a processing page with an animation on it so that the user knows something is being processed. The processing page then recalls the servlet every 3seconds to see if the processing has been completed and if it has the forward to the appropriate results page.
Unfortunately I can not stop users entering large queries as the system requires users to be able to search in excess of 5 million documents on a regular basis.
I'd appreciate any help/suggestions that you may have regarding this matter as soon as possible so I can make the necessary amendments to the application prior to its pilot in a few weeks time.

Answer 1

Hi Steve,
After a few attempts - yes I have a hit a few snags.
I'll send you a copy of the example application that I am working on but this is what I have done so far.
I've taken a standard application that populates a simple java collection (not database driven) with the following structure:
DataPage --> DataAction (refresh Collection) -->DataPage
I have then added this code to the (refreshCollectionAction) DataAction
protected void invokeCustomMethod(DataActionContext ctx)
super.invokeCustomMethod(ctx);
HttpSession session = ctx.getHttpServletRequest().getSession();
Thread nominalSearch = (Thread)session.getAttribute("nominalSearch") ;
if (nominalSearch == null)
synchronized(this)
//create new instance of the thread
nominalSearch = new ns(ctx);
} //end of sychronized wrapper
session.setAttribute("nominalSearch", nominalSearch);
session.setAttribute("action", "nominalSearch");
nominalSearch.start();
System.err.println("started thread calling loading page");
ctx.setActionForward("loading.jsp");
else
if (nominalSearch.isAlive())
System.err.println("trying to call loading page");
ctx.setActionForward("loading.jsp");
else
System.err.println("trying to call results page");
ctx.setActionForward("success");
Created another class called ns.java:
package view;
import oracle.adf.controller.struts.actions.DataActionContext;
import oracle.adf.model.binding.DCIteratorBinding;
import oracle.adf.model.generic.DCRowSetIteratorImpl;
public class ns extends Thread
private DataActionContext ctx;
public ns(DataActionContext ctx)
this.ctx = ctx;
public void run()
System.err.println("START");
DCIteratorBinding b = ctx.getBindingContainer().findIteratorBinding("currentNominalCollectionIterator");
((DCRowSetIteratorImpl)b.getRowSetIterator()).rebuildIteratorUpto(-1);
//b.executeQuery();
System.err.println("END");
and added a loading.jsp page that calls a new dataAction called processing every second. The processing dataAction has the following code within it:
package view;
import javax.servlet.http.HttpSession;
import oracle.adf.controller.struts.actions.DataForwardAction;
import oracle.adf.controller.struts.actions.DataActionContext;
public class ProcessingAction extends DataForwardAction
protected void invokeCustomMethod(DataActionContext actionContext)
// TODO: Override this oracle.adf.controller.struts.actions.DataAction method
super.invokeCustomMethod(actionContext);
HttpSession session = actionContext.getHttpServletRequest().getSession();
String action = (String)session.getAttribute("action");
if (action.equalsIgnoreCase("nominalSearch"))
actionContext.setActionForward("refreshCollection.do");
I'd appreciate any help or guidance that you may have on this as I really need to implement a generic loading page that can be called by a number of actions within my application as soon as possible.
Thanks in advance for your help
David.