Background
For the KiTT Cat project in 2016, one of the functions that we prototyped in OLab was the ability to incorporate collaborative annotation of PDF documents.
The example case that best illustrates this is ‘PSA screening’ at https://demo.openlabyrinth.ca/renderLabyrinth/index/1061
The clinical material regarding PSA screening is derived from one of the PBSG files, created by FMPE. (https://fmpe.org) and is used with their permission.
What you would see
Once you opened the OLab case, you would see a page that included the material from FMPE. You could use the embedded PDF annotation tools to highlight and annotate the PDF file.
Because the file is opened using a shared set of group credentials, all members of the group would be able to see each other’s markup of the PDF document and would be able to append comments to the document.
Methods used
As noted above, the platform that supported this was OpenLabyrinth v3 (OLab3). See https://openlabyrinth.ca/ for background information. Our main OLab3 server is located at https://demo.openlabyrinth.ca and the PSA case itself is playable at https://demo.openlabyrinth.ca/renderLabyrinth/index/1061 as noted above.
On the first page of that case, we then used a widget from H5P (https://h5p.org) to embed the PDF file within an iFrame on the page.
The PDF document itself was placed in a shared folder on Google Drive (under the credentials of dvdtpps@gmail.com for testing but this could be changed to a group login later).
The shared PDF annotation function was provided by MetaPDF.com — we created a placeholder there and then pointed it at our shared PDF document on GDrive.
Provided that your browser was logged in to Google Drive using the correct credentials, this worked well. There was a slight lag before users would see each other’s updates but because this was not supporting collaborative creation of a new document, this was functionally not important.
Method Deprecated
Sadly, on more recent review of this approach on 7feb2025, we note that this embedded annotation no longer works in this case. You can see the iFrame but the content window is empty.
Back-tracing the issues, the primary limiting factor is that MetaPDF.com has been bought by PaperFile and URLs pointing to metapdf.com are redirected but not to the equivalent API. This is not too surprising after 9 years.
The H5P widgets and OLab itself are still working as expected.
We note that the shared PDF annotation was based on an open-source Javascript tool, that is still available and hosted at https://mozilla.github.io/pdf.js/ — it would not take much work to integrate that Javascript tool directly into OLab4, using its Script Objects. (https://olab4.gitbook.io/help/advanced-topics/script-objects)