First of all let me apologize for the late reply.
The DataSource do not have page or sort events. You may check if the sort object or page number has changed at the requestStart event.
The sort object may be retrieved using the sort method of the dataSource and the page - using the page method of the dataSouce.
//compare sort to old sort
//compare page to old page
You may save the current page and sort state at the change event handler of the DataSource which fires after sorting/paging is applied.
I hope this information will help.
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