Friday, July 24, 2009

Info Dictionary vs XMP Metadata

The PDF/A-1 specification goes to great lengths to describe a mapping between the Entries in the legacy PDF Document Information Dictionary and their corresponding values in the more modern Document XMP Metadata. Section 3.4 in TechNote 0003 describes how the values in the Document Information Dictionary must be mirrored in XMP. Section 3.3 describes the requirements for Document Information Entries.

However, these requirements are not symmetric. What I mean by this is that it is perfectly legal for a PDF/A document to contain Document XMP Metadata and not to include a Document Information Dictionary.

Keeping the entries of the legacy and the more modern structures in sync is a headache for the software developer and this pursuit is littered with ambiguous scenarios. For example, many of the XMP Metadata fields can have multiple values. For example, multiple dc:title values for multiple languages or a seq of multiple authors for dc:creator rather than a single author. Each Entry in the legacy Document Information Dictionary is a simple string. There are no conventions on how to order or delimit these strings when mapping multiple fields from XMP to these single string values.

The solution is simple: don't use Document Information Dictionaries! Accept that Document XMP Metadata is the way forward and move on.

We'll be adding this to PDF/D as a constraint: the Info dictionary will be illegal in PDF/D - legacy software be damned.

Wednesday, July 1, 2009

Solid Framework v6 includes PDF/A Validation

It was a quiet month here at Pragmatic PDF central. We've been hard at work on the finishing touches of our Solid Framework v6 upgrade.

Major changes include:
  • new enterprise license model (in addition to republisher model)
  • PDF/A Validation
  • PDF to PDF/A Conversion
  • PDF to flowing HTML conversion
  • support for 64 bit Windows
We also have a much more elaborate set of sample code than before in the form of some free applications. Solid PDF Navigator is 100% free and illustrates what can be achieved with the Free license of SolidFramework. Solid PDF Mechanic uses the new free Developer license to allow exploration of all the premium Solid Framework features. All features are fully functional but include watermarks and "not for resale" text. To take advantage of either the Free or Developer license, simply download Solid Framework and start using it immediately.

PDF viewer including Page Pane and standard navigation controls similar to Acrobat Reader.

Explorer view allows navigation and examination of PDF internals.