Hello everybody! Quick question! I read about PHPExcel and still can not figure out one thing. I perfectly understand that you can grab data from html form, validate it do some calculations pass it to Excel to apply formulas and then recall value back and if you want even generate xls file. My project is based on a spreadsheet, right now it is using jquery plugin for calculations and have a perfect parser for formulas. However, i need to hide formulas and hence make it server-side. Question: phpexcel will allow me to parse complex formulas like vlookup+several if's and so on and how its gonna be done? I mean, there will reside an excel file on the server and script will just recall to it, pass data, excel will calculate it and return back? How it will handle a multiple user's sessions? if i have 30 ppl simultaneously working with a form will it still work?