XML
Nowadays, XML is the native format of many applications, Oracle APEX for example, partly bases its reporting systen on XML. Middleware as Oracle BPEL, SAP PI, IBM Websphere and of course many Web services are also XML based. XML is also being used as exchange format in business to business transactions, for example for e-Invoicing. In these and many other environments there is often the need to create PDF files from XML.
XSL-FO
In the past PDF files would be created using proprietary reporting tools that would use a database as data source. Additionally these tools are programming language specific. Later on the XSL-FO standard allowed for a better way to do it in many cases.
What is new about XSL-FO?
- it is programming language neutral.
- it is a standard so you are not tied to a vendor.
- it uses XML as data source.
Apache FOP
One implementation of the XSL-FO standard is Apache FOP. One important aspect about this implementation is that the Apache license model allows to use it in commercial environment.
Many free/open source products have a license model that puts strong restrictions on the way you may use the software. Not surprisingly there are software companies that do not allow the use in their code any open source software other than Apache Foundation one. So if you use Apache you know you are on the safe side.