using com.apama.dataview.DataViewUpdateItemDelta;
...
string location;
integer temp;
integer humidity;
integer visibility;
...
DataViewUpdateItemDelta update := new DataViewUpdateItemDelta;
update.dvName := "Weather";
update.dvItemId := -1; // Set the ID to -1 when using keyFields.
update.fieldValues :=
   {0:location,1:temp.toString(),2:humidity.toString(),
      3:visibility.toString()};
route update;