Monday, November 11, 2013

Creating a PDF dynamically from an XPage - Part 1

In my Purchase Order project, one of the features I promised to the users would be a professional looking document instead of a printed web page.   Of course this was very well received by the users.  I felt comfortable suggesting this feature because I have previously watched videos showing that it could be done.

The demos that I had watched had one thing in common, they all showed how to create a PDF from a view. In my case, I need to create a single Purchase Order from the contents of an Xpage.  The Xpage that is the PO, actually shows header items stored in one document, and line items which are each stored in separate backend documents. There is an indeterminate number of line items associated with any given PO.   I quickly discovered that this piece of the project will not be easy, and in fact will be time consuming and difficult.  

In this post, the first of a series, I will document the steps to prepare to create PDF's from an Xpage.  The first step you will need to decide is which method to go about this.  The second step is to do your homework and understand the technique you decided to use.

Step 1: Deciding which technique to use.  

There are three distinct technologies available for creating PDF's.  The first is using an FDF file.  My friend Mark Roden was kind enough to give me an overview of this technique.   It seems like it is the easiest solution to create a PDF, but it does have some limitations.   You would use Acrobat (paid version) to create a form and then create a FDF file from your application to tell which data to be placed in which field on the acrobat form.   The format of the FDF is structured file that is neither XML or JSON, but seems pretty easy to pick up.

The limitation is that you would have to know that the number of fields that you need prior to creating the PDF.   In my case, a PO can have any number of line items, so I felt like using this technique would be too limiting.  If you can, I would recommend using this technique for how easy it is.  The techniques below are very different and more time consuming.

The second technique is to use iText.  I watched an older Notes in 9 video on using iText by Brian Moore. The video was very well done, and is a much watch if considering using iText.   I decided to forgo using iText because most of the more recent demonstrations that I found used Apache FOP instead of iText.  

This brings me to the third technique on creating PDFs, XSL-FO using Apache FOP.   My research led me to know that this was my best path to accomplishing my goal.  

Step 2:  Understanding how to use the XSL-FO and Apache FOP

The two resident experts in the Xpages world on using XSL-FO are Stephan Wissel and Paul Calhoun. Stephan has produced a series on his blog on how to use XSL-FO, it is must reading.    Paul has created an Notes in 9 that in 15 minutes or so shows you how to create a PDF from a view.   Paul also includes links to his demo on his site for all to use. 

The other useful site that I helped me was good ole   They have whole sections dedicated to XSLT, XSL-FO and XPATH.  You will need to understand these 'languages' to create PDF's.   You will find yourself learning far more about XML than you ever cared to know.  Best to start brewing a fresh pot of coffee before diving in.

Next Post

In Part 2 of this series, I will document the pitfalls I encountered while trying to get a working proof of concept.  I also want to add that I am still plowing through all this, and I welcome in the comments any corrections if I say anything wrong. 

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