New Memento support at Perma.cc

[Rebecca Cremona]

Good evening!

Tomorrow (Weds Feb 4, 2020), Perma.cc will begin the process of deploying completely reimplemented support for timegates, timemaps, and memento-related headers on Perma Link/memento playbacks. Our timemaps, timegates, and memento-related headers have been broken since early last summer; we apologize for the frustration, and that it took us so long to address.

We expect the full re-indexing to take several hours, possibly up to a full day. During this time, Perma will initially return 404 for all timemap and timegate queries; partial results will be exposed in real time as the index is re-built. I'll post to this list again when it's complete.

Timemaps will subsequently be available at:

https://perma.cc/timemap/link/<url> (replacing https://perma-archives.org/warc/timemap/*/<url>)

https://perma.cc/timemap/json/<url> (newly available)

https://perma.cc/timemap/html/<url> (non-standard, browser-friendly format, replacing https://perma-archives.org/warc/*/<url>)

and timegates will be available at:

https://perma.cc/timegate/<url> (replacing https://perma-archives.org/warc/timegate/<url>)

We will 301 redirect from the old routes to the new ones.

More details are below, if anyone is interested or might be tripped up by our changes.

We hope this whips Perma's Memento support into shape. We've run the validator (http://mementoweb.org/tools/validator) against our staging server (https://perma-stage.org), and it looks good, but I can now easily tweak the output as needed.

If anyone has questions, concerns, recommendations, etc., just let me know!

All best,

Rebecca

-

Rebecca Cremona

Developer

Harvard Library Innovation Lab

rcre...@law.harvard.edu

----------

More Details:

In addition to addressing the various known bugs in our former implementation, we're making three changes of note:

1) 

Apropos of https://groups.google.com/forum/#!topic/memento-dev/sys8DeUtmWU: Perma.cc plays back all mementos within an iframe. Sawood asks, "Should the parent/wrapper URI be returned in Memento related Link headers or the inner iframe URI (or both maintain their independent URI-Ms)?" 

It is not at present possible to play back a Perma.cc memento without its wrapping iframe, and so we will now be return the parent/wrapper URI as the URI-M (e.g. https://perma.cc/AAAA-AAAA, rather than https://perma-archives.org/warc/AAAA-AAAA/<url>. The inner iframe URI is now strictly for internal use.

2) 

Relatedly, it is not at present possible to request the playback of anything but a complete Perma Link. That is to say, if a Perma user made a capture of lil.harvard.edu at https://perma.cc/B2ND-UEGX, you can play back https://perma.cc/B2ND-UEGX, but you can't playback the archived copy of lil.law.harvard.edu/assets/css.main in isolation, all by itself. Therefore, we will only be exposing timemaps and timegates for the top-level captured URLs, not for every resource in our warcs. 

We will therefore be returning 404 for a lot more timemap and timegate queries than we did in the past.

We may be able readdress this in the future, if we can implement support for isolated playback of individual assets within a Perma Link.

3)

Only publicly-available Perma Links will be listed in timemaps or redirected to via timegates. Users should no longer uselessly get redirected to private, deleted, or potentially transient (e.g. less than 24-hours old, and still subject to user deletion) Perma Links. If, via a non-standard mechanism, a user encounters a playback of a Perma Link they would not be able to discover via a timemap or a timegate, that playback will NOT include headers like link or memento-datetime in the response, to avoid confusion.

[Rebecca Cremona]

The migration is complete!

We will keep the redirects up indefinitely; aggregators may prefer to update to the new routes.

All best,

Rebecca