On The Significant Properties of Spreadsheets

24 September 2021
Clippy saying It looks like you're migrating a spreadsheet to ... TIFF?!

Earlier this month saw the publication of The Significant Properties of Spreadsheets. This is the final report of a six-year research effort by the Open Preservation Foundation’s Archives Interest Group (AIG), which is composed of participants from the National Archives of the Netherlands (NANETH), the National Archives of Estonia (NAE), the Danish National Archives (DNA), and Preservica. The report caught my attention for two reasons. First, there’s the subject matter of spreadsheets, on which I’ve written a few posts in the past1. Second, it marks a surprising (at least to me!) return of “significant properties”, a concept that was omnipresent in the digital preservation world between, roughly, 2005 and 2010, but which has largely fallen into disuse since then. In this post I’m sharing some of my thoughts on the report.


PDF processing and analysis with open-source tools

06 September 2021
Plumbers Tool Box
Plumbers Tool Box by pszz on Flickr. Used under CC BY-NC-SA 2.0.

Over the years, I’ve been using a variety of open-source software tools for solving all sorts of issues with PDF documents. This post is an attempt to (finally) bring together my go-to PDF analysis and processing tools and commands for a variety of common tasks in one single place. It is largely based on a multitude of scattered lists, cheat-sheets and working notes that I made earlier. Starting with a brief overview of some general-purpose PDF toolkits, I then move on to a discussion of the following specific tasks:

  • Validation and integrity testing
  • PDF/A and PDF/UA compliance testing
  • Document information and metadata extraction
  • Policy/profile compliance testing
  • Text extraction
  • Link extraction
  • Image extraction
  • Conversion to other (graphics) formats
  • Inspection of embedded image information
  • Conversion of multiple images to PDF
  • Cross-comparison of two PDFs
  • Corrupted PDF repair
  • File size reduction of PDF with hi-res graphics
  • Inspection of low-level PDF structure
  • View, search and extract low-level PDF objects

Towards a preservation workflow for mobile apps

24 February 2021
Satellite image of Wadden Sea
Production photo from "2001: A Space Odyssey". ©Stanley Kubrick Archives/TASCHEN.

My previous post addressed the emulation of mobile Android apps. In this follow-up, I’ll explore some other aspects of mobile app preservation, with a focus on acquisition and ingest processes. The 2019 iPres paper on the Acquisition and Preservation of Mobile eBook Apps by Maureen Pennock, Peter May and Michael Day again was the departure point. In its concluding section, they recommend:

In terms of target formats for acquisition, we reach the undeniable conclusion that acquisition of the app in its packaged form (either an IPA file or an APK file) is optimal for ensuring organisations at least acquire a complete published object for preservation.

And:

[T]his form should at least also include sufficient metadata about inherent technical dependencies to understand what is needed to meet them.

In practical terms, this means that the workflows that are used for acquisition and (pre-)ingest must include components that are able to deal with the following aspects:

  1. Acquisition of the app packages (either by direct deposit from the publisher, or using the app store).
  2. Identification of the package format (APK for Android, IPA for iOS).
  3. Identification of metadata about the app’s technical dependencies.

The main objective of this post is to get an idea of what would be needed to implement these components. Is it possible to do all of this with existing tools? If not so, what are the gaps? The underlying assumption here is an emulation-based preservation strategy1.


Four Android emulators, two apps

09 February 2021
Header image
"Android Robot" by Google Inc., used under CC BY 3.0, via Wikimedia Commons.

So far the KB hasn’t actively pursued the preservation of mobile apps. However, born-digital publications in app-only form have become increasingly common, as well as “hybrid” publications, with apps that are supplemental to traditional (paper) books. At the request of our Digital Preservation department, I’ve started some exploratory investigations into how to preserve mobile apps in the near future. The 2019 iPres paper on the Acquisition and Preservation of Mobile eBook Apps by the British Library’s Maureen Pennock, Peter May and Michael Day provides an excellent starting point on the subject, and it highlights many of the challenges involved.

Before we can start archiving mobile apps ourselves, some additional aspects need to be addressed in more detail. One of these is the question of how to ensure long-term access. Emulation is the obvious strategy here, but I couldn’t find much information on the emulation of mobile platforms within a digital preservation context. In this blog post I present the results of some simple experiments, where I tried to emulate two selected apps. The main objective here was to explore the current state of emulation of mobile devices, and to get an initial impression of the suitability of some existing emulation solutions for long-term access.

For practical reasons I’ve limited myself to the Android platform1. Attentive readers may recall I briefly touched on this subject back in 2014. As much of the information in that blog post has now become outdated, this new post presents a more up-to date investigation. I should probably mention here that I don’t own or use any Android device, or any other kind of smartphone or tablet for that matter2. This probably makes me the worst possible person to evaluate Android emulation, but who’s going to stop me trying anyway? No one, that’s who!


Mapping the Dutch web domain

09 September 2020
Satellite image of Wadden Sea
“World Wide Web - Digital Preservation” by Jørgen Stamp, used under CC BY 2.5 DK; “Wadden Sea” by Envisat satellite, used under CC BY-SA 3.0-IGO.

Earlier this year I wrote a blog post about geo-locating web domains, and the subsequent analysis of the resulting data in QGIS. At the time, this work was meant as a proof of concept, and I had only tried it out on a small set of test data. We have now applied this methodology to the whole of the Dutch (.nl) web domain, and this follow-up post presents the results of this exercise.



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