Conversion RTF to PDF documents is being realized with the help of Apache FOP.
Apache FOP (Formatting Objects Processor) is the world's first print formatter driven by XSL formatting objects (XSL-FO) and the world's first output independent formatter. It is a Java application that reads a formatting object (FO) tree and renders the resulting pages to a specified output. Output formats currently supported include PDF, PCL, PostScript (PS),XML (area tree representation), Print, AWT , MIF and TXT. The primary output target is PDF. Support for each of the standard's objects and properties is detailed in FOP Compliance. FOP is proud to be part of Apache's XML Graphics project.
The goals of the Apache FOP project are to deliver an XSL-FO to PDF formatter that is compliant to at least the Basic conformance level described in the W3C Recommendation from 15 October 2001, and that complies with the 11 March 1999 Portable Document Format Specification (Version 1.3) from Adobe Systems.
Conformance to the XML 1.0 Recommendation, XSLT 1.0 Recommendation and the XML Namespaces Recommendation is understood. Other relevant documents, such as the XPath and XLink Working Drafts, are referenced as necessary. The FOP Project will attempt to use the latest version of evolving specifications. The FOP layout system is currently being rewritten to better support the XSL-FO standard.