We introduce MementoMap, a framework to express and disseminate holdings of web archives (archive profiles) by themselves or third parties. The framework allows arbitrary, flexible, and dynamic levels of details in its entries that fit the needs of archives of different scales. This enables Memento aggregators to significantly reduce wasted traffic to web archives.

1. MementoMap
An Archive Profile Dissemination Framework
Sawood Alam, Michele C. Weigle, and Michael L. Nelson
Old Dominion University, Norfolk, VA, USA
@ibnesayeed @WebSciDL
Supported by NSF Grant IIS-1526700
WADL '19, June 6, 2019, Urbana-Champaign, Illinois

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$ memgator -a archives.json -f cdxj example.com
> | grep -v "^!" | cut -d '/' -f 3 | sort | uniq -c | sort -nr
198014 web.archive.org
13548 wayback.archive-it.org
1191 webarchive.loc.gov
1044 swap.stanford.edu
953 arquivo.pt
525 wayback.vefsafn.is
225 perma-archives.org
221 archive.md
23 www.webarchive.org.uk
$ memgator -a archives.json -f cdxj jcdl.org
> | grep -v "^!" | cut -d '/' -f 3 | sort | uniq -c | sort -nr
410 web.archive.org
2 www.webarchive.org.uk
2 arquivo.pt
1 archive.md
Cross-archive Memento Lookup With MemGator
https://github.com/oduwsdl/MemGator

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Memento Aggregator
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Memento Aggregator
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Memento Aggregator
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Memento Aggregator
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Memento Aggregator
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Memento Aggregator
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Broadcasting is Evil
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From: Michael Nelson [mailto:mln@cs.odu.edu]
Sent: Wednesday, December 02, 2015 12:33 PM
To: Jones, Gina
Cc: Rourke, Patrick; Grotke, Abigail
Subject: Re: WebSciDL
Hi Gina, I'll investigate. memgator is software that one my students wrote, but I suspect the
traffic you're seeing is b/c it is deployed in http://oldweb.today/ can you share the IP
addr from where you're seeing the traffic? I presume the requests are for Memento
TimeMaps? It should not being actually scraping HTML pages.
regards,
Michael
On Wed, 2 Dec 2015, Jones, Gina wrote:
> Hi Michael, we have a slight configuration issue with the current OW
> set up for our webarchives. I think, from looking at the logs, that
> "MemGator:1.0-rc3 <@WebSciDL>" is really causing some issues on our wayback.
> Do you know who is running this scraper? Itʼs not part of memento is it?
>
> Gina Jones
> Web Archiving Team
> Library of Congress
From: Ilya Kreymer <ikreymer@gmail.com>
Date: Wed, 2 Dec 2015 10:33:56 -0800
Subject: high traffic on oldweb!
To: Herbert Van de Sompel <hvdsomp@gmail.com>, Sawood Alam
<ibnesayeed@gmail.com>
Hi Herbert, Sawood,
Herbert: Perhaps you are lucky that I am not using the LANL aggregator, as the traffic has
gotten really high, and also I was asked to remove an archive due to the traffic it was
causing temporarily..
I am thinking that ability to remove source archives quickly is an important aspect of an
aggregator.
Sawood: Hopefully yours will support something like this so I don't need to restart the
container to change the archivelist ;)
Ilya
Broadcasting is wasteful, both clients & archives suffer!

10. @ibnesayeed
Memento Lookup Routing
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Let’s fix the broadcasting issue
with a more informed routing.

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MemGator Log Responses from Various Archives
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93% of the requests
made from MemGator
to upstream archives
were wasteful.

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What is Archived in Arquivo.pt?
What is Accessed from MemGator?
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Blind spot of a
content-based profile
Blind spot of a
usage-based profile

13. @ibnesayeed
If Only Archives Could Tell When to Ask Them
● Websites advertise their holdings using sitemap.xml, why can’t archives?
○ Archives have billions or even hundreds of billions URI-Ms
○ Such exhaustive lists would go stale very quickly
● How about robots.txt?
○ It is compact, but is exclusion format, it does not tell what the site has
○ It assumes a single domain, patterns are for paths (not the domain name)
● How about combining the two ideas?
○ Introducing MementoMap!
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A MementoMap Example
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!context ["http://oduwsdl.github.io/contexts/ukvs"]
!id {uri: "http://archive.example.org/"}
!fields {keys: ["surt"], values: ["frequency"]}
!meta {type: "MementoMap", name: "A Test Web Archive", year: 1996}
!meta {updated_at: "2018-09-03T13:27:52Z"}
* 54321/20000
com,* 10000+
org,arxiv)/ 100
org,arxiv)/* 2500~/900
org,arxiv)/pdf/* 0
uk,co,bbc)/images/* 300+/20-
+ for a lower boundary
- for an upper boundary
~ for an approximate value

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Unified Key Value Store (UKVS)
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https://github.com/oduwsdl/ORS/blob/master/ukvs.md

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UKVS Optional Fields vs. Key Columns
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UKVS Use Cases
● MementoMap
● CDX File/Server
● Archive ACL
● Archive Fixity
● Extended TimeMap
● … and many more
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SURTs Representation with Wildcard
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Original SURTs did not have wildcards.
In practice the common “http://(” prefix
is removed.

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Arquivo.pt Index Statistics
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The Internet archive is
about 150 times bigger
than Arquivo.pt.

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Shape of HxPx Key Tree of Arquivo.pt
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Who Would have Thought
Arquivo.pt has 10K+ .онлайн Sites?
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“.онлайн”
(encoded as “xn--80asehdb”)
is an IDN gTLD which means
“.online”

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Most Archived URI-Rs in Arquivo.pt
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Arquivo is obsessed with transparent single pixel images and corner graphics.

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Processed Lines vs. Compacted MementoMap Growth
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com,example)/a/1/x
com,example)/a/2
com,example)/a/3
com,example)/b/1
com,example)/b/2
com,example)/c/1
com,example)/a/*
com,example)/b/1
com,example)/b/2
com,example)/c/1
com,example)/*

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MementoMap Generation, Compaction, and Lookup
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1.5% Relative Cost yields 60% Accuracy.
Arquivo.pt can save 60% waisted traffic
by publishing 119MB summary file!

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Dissemination and Discovery Methods
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GET /.well-known/mementomap HTTP/1.1
Host: arquivo.pt
Link: <https://arquivo.pt/path/to/mementomap.ukvs>;
rel="mementomap"
<link href="https://arquivo.pt/path/to/mementomap.ukvs"
rel="mementomap">
Well-known URI
Link Header
Link HTML Element

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Future Work
● Generate blacklists by processing access logs
● Incorporate MementoMap in replay systems
● Encourage archives and aggregators to adopt it
● Encourage use of UKVS in other archival and non-archival contexts
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Conclusions
● Described MementoMap - a flexible and efficient archive profiling framework
● Analyzed complete index of Arquivo.pt to understand nature of web archives
● Evaluated MementoMap against Arquivo.pt’s index
● Save 60% of the wasted MemGator traffic with 1.5% cost (a 119 MB file)
● Proposed “mementomap” as a well-known URI suffix as well as a link relation
for dissemination of MementoMap
● Implemented a single-pass, memory-efficient, and parallelization-friendly
MementoMap generation/compaction algorithm
● Open-sourced the implementation
○ https://github.com/oduwsdl/MementoMap
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