OPML

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Posted by satis
Dec 13, 2021 at 02:59 PM

Dave Winer wrote an interesting blog post over the weekend about the history of OPML. (But he really needs to get his site onboard with https.)

http://scripting.com/2021/12/11/145032.html

Posted by Luhmann
Dec 13, 2021 at 04:28 PM

Anyone with some technical knowledge understand the advantages/disadvantages of OPML vs. JSON vs. EDN? It seems to me that whereas a decade ago a lot of apps used OPML, most now use JSON instead, and some use EDN as well…

Posted by Maurice Parker
Dec 13, 2021 at 06:54 PM

OPML is XML based and uses the most storage. It is also probably the slowest to parse and load. It feels wasteful compared to other formats, but practically speaking, todays computers are so fast and capable that it is hard to notice the inefficiencies.

OPML’s main strength is that it is a generally accepted standard for outlines. Most apps support importing and exporting it. Unfortunately, it is a very loosely defined standard and has been extended in sometimes incompatible ways. As you can see in Dave’s post, he is of a mind that you can do what ever you want with it. This is great if you are using it for an internal format for your application. It is not so great if you are trying to exchange data with other applications.

What I decided to do with Zavala is have an internal database of files that is faster to load and save than OPML and use OPML as an interchange format with other applications. I think this is the best compromise. Unfortunately, I too have extended OPML to enable full fidelity for the outlines that I allow Zavala to create. For example, I consider Markdown to be valid in the text fields of the OPML file. This allows me to include formatting, links, and other inline structures that aren’t part of the OPML spec.

Ideally one of the big players would champion a way to bundle multiple, linked outlines with embedded media into a single archive file. That would allow people to move their PKB between applications as needed. Unfortunately there is little financial incentive to make it easy for people to leave your platform, so we will be mostly stuck with information silos for the foreseeable future.

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