to implement online converting engine from browser to web server

Hello im looking for common way to build the right client server architecture when my goal is : the browser submit data to the web server -> the web server response with converted pdf file based on that data now my question is this : where to implement this convention engine ( that is static lib ) as web server plug in (apache, lighthttpd,nginx)? or as separate process in different server ?

From stackoverflow

• This sounds to me like you are wanting to dynamically generate PDFs based on the data captured from a web-based form? If so, there are many different ways to achieve this- and each person from each language discipline will promote their method as being simple.

  : i know , this is what i like to learn