DataProcessor sendData() function, number of Columns

I use a DataProcessor with a grid. When I call sendData(), I get the information of the changes in the server update proecssor. I extract all the data using request parameters like ‘gr_id’, ‘c0’, ‘c1’, ‘c2’, ‘c3’ etc. Is there a way of knowing the total number of columns in the row?

DataProcessor sends data for all columns in grid, but doesn’t provide exact number as separate parameter. ( because processing url must be related to the grid on client side, it was expected that info about expected count of data available on server side )