如何创建ruby脚本来解析用户上传的文件？

I want users to be able to upload files and then I want to be able to parse them, taking out pieces of information and then declaring them as global variables to be used by other parts of my web application. I know you can easily put in a file upload form but then where would I store the script for parsing the file? Would it be under models, views, controllers, or somewhere else? Also how can I tell my application to immediately run this script upon the file upload. Would I put it in the view before the form's <% end %> tag? When it does parse the file, how can I make sure the variables (probably array's) are declared globally so that I can call those variables in all other parts of my applicationI want users to be able to upload files and the