What I have done:

1) created an xml stream and mapped with the source pagelist to create xml.

2) Property set xml is done in the activity

3) next step of activity, below java code:

ClipboardPage objHeadersPage = tools.findPage("pxRequestor").getProperty(".pyHTTPResponseHeaders").getPageValue();

objHeadersPage.putString("contentType" ,"application/vnd.ms-excel");

objHeadersPage.putString("ContentDisposition" ,"attachment;filename=ExportData.xml");

4) The wrapper xml with the below content type is called.

<?xml version="1.0" encoding="UTF-8"?>
<?mso-application progid="Excel.Sheet"?>

The ExportData.xml is creaed but directly doesn't open in excel. There is a confirm box to confirm to open xml data in excel then only it opens in excel.

***Edited by Moderator Marissa to update categories***