Ben bir mağaza kullanan bir ızgara var, mağaza gelen verileri alır

proxy: new Ext.data.HttpProxy({url: 'http:.../request.php'}),

On the same page I have a form. My goal is to refresh and populate the grid with new data composed by the query from DB via php.
I have heard there is a way to do so using php and saving the data in a json file on the server (so that the store would use the file), but doesn't it make impossible for two users work simultaniously?
Is there another way to do it?