Memento Demos

About Demos Guide Tools Depot

For everyone:

Install the MementoFox plug-in that we developed for the for FireFox browser.
Visit the continuously changing pages at LANL or Old Dominion University that we have set up for your enjoyment.
Activate the MementoFox plug-in (click on the logo at the left side), and set the date to some value between 2009-10-12 and now.
Don't forget to click on some links at the bottom of the page. They lead you into Wikipedia. But as you will notice, not to the current Wikipedia pages ... You are time traveling!
Now turn MementoFox back off (click on the logo). You're back.

For the Linked Data advocate who understands that data can't exist without versions:

Install the MementoFox plug-in that we developed for the for FireFox browser.
Activate the MementoFox plug-in (click on the logo at the left side), and set the date to some value between 2007-09-01 and now.
Enter your favorite DBpedia subject URI in the browser's address bar, e.g. http://dbpedia.org/resource/DJ_Shadow.
Let yourself go, and click on some links... You are time traveling!
Turn MementoFox back off (click on the logo) and you're back.

For the HTTP techie who wants to understand the Memento magic and start hacking away:

Install the MementoFox plug-in that we developed for the for FireFox browser.
Install the HTTPFox or the Live HTTP headers FireFox plug-in.
Activate the MementoFox plug-in (click on the logo at the left side), and set the date to some value between 2007-09-01 and now.
Now just repeat the above demos, and check out the HTTP headers used in Memento: Accept-Datetime, Memento-Datetime, Vary, Link, Location.

For those who want to understand the power of the resource versioning approach that derives from Memento, this flip book movie is a fun illustration. This is how it was created:

For months, subtly changing "pictures of the day" were published that depict members of the Memento team posing next to a flip chart. The changes are in the shirts, the timestamps, and the BBC or CNN content superimposed on the flip charts.
At any moment in time, the current picture of the day is served from the following URIs:
- http://lanlsource.lanl.gov/pics/picoftheday.png for Los Alamos;
- http://odusource.cs.odu.edu/pics/picoftheday.png for Old Dominion.
On a daily basis, these images are archived using a transactional archive approach. As a result, old versions of these pictures become available at URIs like:
- Los Alamos picture originally served on March 20th 2010: http://mementoarchive.lanl.gov/ta/20100320180023/http://lanlsource.lanl.gov/pics/picoftheday.png;
- Old Dominion picture originally served on October 9th 2009: http://mementoarchive.cs.odu.edu/ta/20091009160013/http://odusource.cs.odu.edu/pics/picoftheday.png.
Using the following script that targets the URI of a picture of the day (say http://lanlsource.lanl.gov/pics/picoftheday.png) with incrementing datetime values for HTTP content negotiation and "follow your nose" HTTP navigation, all pictures of the day were gathered. In essence, the URI is asked about its past, and the URI gracefully responds by pointing at a TimeGate that knows about its past, and redirects to archived images that match the requested datetime values.

#!/usr/bin/python import os, sys, urllib2 from datetime import datetime, timedelta fmtstr = "%a, %d %b %Y %H:%M:%S GMT" img = "http://lanlsource.lanl.gov/pics/picoftheday.png" timegate = "http://mementoarchive.lanl.gov/store/ta/timegate/" first = datetime.strptime("Mon, 30 Sep 2009 19:00:00", fmtstr[:-4]) (now, td) = (datetime.now(), timedelta(1)) (savePath, typ) = ('/path/to/save', 'png') def get_memento(t): req = urllib2.Request(timegate + img) req.add_header('Accept-Datetime', t.strftime(fmtstr)) fh = urllib2.urlopen(req) data = fh.read() when = fh.headers.dict.get('memento-datetime', '') dt = datetime.strptime(when, fmtstr) if when else None fh.close() return (dt, data) def iterate(): (t, i, odt) = (first, 1, None) while t < now: (dt, data) = get_memento(t) if dt != odt: fn = os.path.join(savePath, "%04d.%s" % (i, typ)) fh = file(fn, 'w') fh.write(data) ; fh.close() odt = dt ; t += td ; i += 1 sys.stdout.write('.') ; sys.stdout.flush() iterate()
The gathered pictures were then concatenated to obtain this flip book movie.