XML File download through an iview

Question

Hi All,
I've written an iview that builds up the data for an xml file and tableview report. The should be able to click a link on the iview and a window pops up and they can save the XML data to a local file.
I have two problems, the first is I am unsure how to pass the large amount of data from the first iview to the second "Download" iview. It is too big to fit as a form parameter. I'm hoping to add it to the component session. Do you think this will work?
The second problem is the download itself. I've created a basic component with a doContent method. I've tried setting the content type to "Application/octet-stream" by using the following code :
public class ecDownloadComponent extends AbstractPortalComponent
    public void doContent(IPortalComponentRequest request, IPortalComponentResponse response)
          PortalComponentContentType pct = new PortalComponentContentType("APPLICATION/OCTET-STREAM");
          response.setContentType(pct);
          response.write("<xml>hello</xml>");
All I get is an HTML page with the data in.
Any ideas how I force the download?
Cheers
Richard

Answer 1

Hi Richard,
1.) If the complete data which should be downloadable is built in the first iView, it is no problem to add it to the component session. "Size doesn't matter"
What happens "physically" if you add something to a session? In fact, a <i>reference</i> to your (small or incredible fat) object is added into a hashtable or something similar.
(Excurs: That's why objects in sessions are called "live", because if you get a reference to an object of a session and manipulate this object with it's methods, the object in the session is manipulated, because it's the same object; that's the reason why you don't have to "update" such an object into the session).
So you don't have to worry about using the double amount of memory, because you are not.
2.) For iViews to be something different than HTML, put all the stuff into the overridden method <i>protected void doOnNodeReady(IPortalComponentRequest request, IEvent event)</i>, retrieve the original HttpServletResponse via <i>HttpServletResponse response= request.getServletResponse(true);</i> and set the ContentType on this.
The trick is to be "early enough" in the sense that the content type must not have been set before.
With this, just implement an empty <i>doContent</i> method and put the rest of your download logic in the method stated above.
Just one more info, not needed here, but maybe interesting in this context: If you want do produce PDF's in this way, you have to be sure to put the PDF data "fast enough" into the output stream, otherwise the PDF-Reader could get stuck. This means <i>first</i> setting all data into a memory buffer and then sending this into the outputstream (and not calculating the data "while sending").
Hope it helps
Detlev