It’s a question that vexes vendors of web-based solutions everywhere: why do people still insist on PDF files? And why does PDF’s mindshare keep going up? “PDF is such antediluvian technology!” they say. “It’s pre-web, are you kidding me? It’s so old-f …PDF Association technical resources: an overview
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In 2015 there are plenty of software developers younger than the PDF format, published in 1993. Few of them think much about PDF. Whats hot in software development these days is the web, mobile computing, cloud services and other networking technologies.
What can a 22 year old page-description model offer to developers with something to prove?
Quite a lot.
This article highlights three areas in which supporting various features of PDF can help developers offer new and powerful options to their product and project managers. While there are many features to mention, these three apply straightforwardly to web-connected implementations, and thus relate to whats hot in software development today.
Lets start with something of straightforward value: making things work faster, with less bandwidth consumed. Both users and server administrators like that sort of thing!
Linearization of PDF enables efficient incremental access in a network environment. PDF processors that support this feature can enhance performance in several ways:
Linearization is less important for smaller files, but many PDF documents are 10, 20, 50 or even hundreds of megabytes, and bandwidth varies substantially for different users. Linearization is an effective strategy for ensuring that pages are displayed on-screen very quickly, even for massive documents, but the feature may also be leveraged for indexing, data mining and other applications.
Being documents, PDF files are objects that users frequently wish to annotate by adding or editing comments, strike-outs, highlights, etc. Sometimes its desirable to add arrows or boxes, or even voice recordings or supplementary files.
PDF can accommodate all that. The format offers a fully standardized model that allows developers to use their preferred look and feel. Theres no need to copy Adobe’s style.
Even better for the connected world; the PDF model includes lightweight mechanisms such as FDF and XFDF which facilitate transaction of annotations with a server.
Perhaps your users want to markup documents in the cloud, with each user receiving updates when others make changes? PDF provides all the structures youd need to accomplish that, and more. The annotation model also includes a variety of metadata. Developers can build a complete, flexible, web-friendly and highly interoperable annotation system that leverages the metadata elements defined in the PDF specification.
To learn more about annotations in PDF see clause 12.5 in ISO 32000-1.
One of the perennial complaints about PDF is that its just a page. Gathering indexable content or repurposing text or graphics can produce surprising results because, among other reasons, PDF does not require that page content be organized as a human would consume it.
For that, theres tagged PDF.
Introduced with PDF 1.4 in 2001, tagged PDF defines structure types and attributes that allow page content (text, graphics and images, annotations and form fields) to be extracted and reused for other purposes.
Tagged PDF (specified in clause 14.8 of ISO 32000-1) allows developers to distinguish the author’s intended content from decorative artifacts, arrange content into correct logical order for reuse, and characterize the semantics of content via structure elements specifying headings, lists, tables and so on.
Software leveraging tagged PDF documents can deliver very high quality results when converting from PDF to HTML, capturing text for indexing, reading text aloud, and for many other interactive and non-interactive purposes. Theres even a subset standard, PDF/UA (ISO 14289), that provides comprehensive instructions for using tagged PDF correctly for the purposes of accessibility to disabled users.
To learn more about tagged PDF see clause 14.8 in ISO 32000-1.
PDF is far richer than a page-description model. Not only does the format include a broad range of powerful features but its ISO-standardized. Whats more, PDF isnt going anywhere its accepted world-wide as the de facto standard for final-form electronic documents.
Developers thinking about use-cases that involve documents should consider the wide range of possibilities affording by this rich, open and universally-accepted format.
Want to learn more? Join your fellow developers at the PDF Technical Conference 2015, in San Jose!