xls to pdf conversion in unix

Hi gang, I did a little research to find out how can someone convert an xls file into pdf and I found that you can use openoffice to do that (already done that in perl). My problem is that I need to find a way for doing this without openoffice by using just PHP. I know that I could probably parse the xls using a reader and then write the data in a pdf with a module (like fpdf or pdflib) but I will get into complications I cannot resolve. So is there another way to do such a transformation. Give me your light... -- Thodoris