Quentin Lobbé
email: quentin.lobbe@telecom-paristech.fr

Ltci

Revealing Historical Events out of Web Archives

Keywords: Web archives, event detection, online migrants collectives

As the living Web expands, worldwide volumes of Web archives constantly increase, making difficult to identify relevant archived contents. Here we propose an application for detecting historical events out of a corpus of Web archives and based on an entity called Web Fragment: a semantic and syntactic subset of a given Web page. The Web fragment has the particularity to be indexed by its edition date instead of its archiving date. We apply our framework on an archived Moroccan forum and witness how it reacted to the Arab Spring at the end of 2010.

Introduction

Since the creation of the Web in the early 90's [START_REF]CERN: The document that officially put the world wide web into the public domain[END_REF], the loss of the digital content that constitutes the Web itself has been considered a major issue [START_REF] Kahle | Preserving the internet[END_REF]. Whereas related works mainly focus on upstream Web archive acquisition [START_REF] Masanès | Web Archiving[END_REF], we choose here to perform the exploration of an existing corpus. But apart from the online portal of the WayBack Machine1 , the majority of corpora of Web archives only allows local consultation points, with no remote access or API. In this paper, we first introduce the usage of a new entity called Web fragment to guide researchers through Web archives at retrieval time (Section 2). As we think that most explorers of Web archives pursue the discovery of events of some sort, we describe an application called Web Archive Explorer (WAE) for detecting historical events (Section 3). We finally use the WAE to understand how the Moroccan forum yabiladi.com reacted to the Arab Spring at the end of 2010 (Section 4).

Setup

An online migrants collective. As input data for WAE we use the Moroccan section of the e-Diasporas Atlas [START_REF] Diminescu | e-Diasporas Atlas. Explorations and Cartography of Diasporas on Digital Networks[END_REF]. The Atlas revealed diasporic communities organized as networks of migrant Web sites connected to each other through hypertext links. But facing the partial or total disappearance of some of the observed Web sites, it was decided to start archiving them. Thus, the corpus was archived from March 2010 to September 2014, covering 254 Web sites 2 . In section 4, we will focus on the Moroccan forum yabiladi.com: an old established Web site, representing a set of 2.8 million archived Web pages.

Web fragment. A Web fragment is a coherent set of textual, audiovisual or animated contents extracted from a Web page and understandable on its own. It can be a meaningful object like a post inside a forum, a news article, or a comment, and it has the particularity to be indexed by its edition date (the time when it was written). We assume that an original edition date will always be more historically accurate than the download date of the parent archived Web page. In practice, a Web fragment is the result of the aglomerative clustering of some of the HTML nodes that constitute a given Web page. To extract them, we extend the boilerplate method from [START_REF] Kohlschütter | Boilerplate detection using shallow text features[END_REF] and use a combination of vision-based [START_REF] Cai | Vips: a vision-based page segmentation algorithm[END_REF] and tag-based scraping strategies [START_REF] Jatowt | Detecting age of page content[END_REF].

Event detection model. Following our logic of archive exploration, we don't want to detect specific events with expert knowledge, so we avoid patterns and clustering methods. We instead use a threshold-based heuristic [START_REF] Fung | Parameter free bursty events detection in text streams[END_REF] within a sliding time frame of one week. We define an event as a detected outlier in the temporal distribution of a set of Web fragments that matches a given keyword. We try explaining the events by finding semantic correlation between the text content of the Web fragments (splited in bigrams) and a set of Morrocan news titles. As yabiladi.com is a combination between a news provider and a forum, we choose to construct an index of potential events using the titles and the edition dates extracted from its news section. To sum up, a historical event is the semantic encounter between a well-dated news title and a burst of web fragments.

Architecture

We now introduce the components of WAE3 . We refer to Figure 1 as an illustration of its architecture : (1) Our data set is recorded under the Digital Archive File Format (DAFF) formalism that separates the metadata (URL, download date, etc.) from the archived data contents (original HTML content). Our Moroccan corpus results in a 30GB metadata DAFF file and a 300GB data DAFF file.

(2) The ArchiveMiner component grabs the files using a Java extractor which uploads them into a Hadoop Distributed File System (HDFS). Then a distributed Spark 4 pipeline ingests the HDFS and groups the metadata by time-stable versions and joins them to the data contents. A set of filters based on download dates or domain names are then applied. (3) We enrich the original corpus by adding qualitative informations such as the main language (French, Moroccan, Spanish, etc.) or category (forum, blog, media, etc.) of each Web site. (4) The FragmentsExtractor component divides each archived Web page into Web fragments (Section 2). Every edition date is translated from a natural language format into a normalized date format. Additionally, the component extracts the text content, author and title of each Web fragment and joins them with the information inherited from the parent Web pages (URL, download date, etc).

(5) The ArchiveSearch component indexes the Web fragments into a Solr search engine. A lemmatizer is then applied to increase the accuracy of the full-text facilities. Custom requestHandlers are built to allow different time query strategies. [START_REF] Kahle | Preserving the internet[END_REF] The WAE provides two different inverted indexes (Section 2): first the Web fragments extracted from the forum section of yabiladi.com and then the events extracted from its news section. [START_REF] Kohlschütter | Boilerplate detection using shallow text features[END_REF] The ArchiveViz component provides an interface to request the archives by writing a set of keywords and choosing the granularity of the query : Web pages or Web fragments. The results are displayed as a list of documents, illustrated with histograms and a bigrams viewer linked to the events detection system.

Demonstration scenario

We now describe5 a set of use cases where WAE helps to reveal historical events :

(1) The user first tries to query the Wayback Machine. But, as it is built on top of a search-by-URL system, the keywords morroco king do not match the real content of the archived Web pages. They can only match strict URLs or HTML titles. (2) With our system, the user request for roi (meaning king in french) and selects pages for granularity. The user has to pick up a range of dates to filter the archives. The top ten resulting archived pages are ordered by default Lucene similarity. (3) The user now specializes his query by focusing on one of the main author contributions. The 5 most prolific authors are displayed in the facets section of the GUI. (4) One can use the first histogram to see the number of matching Web pages by week. Below, there is a line chart displaying the ratio of matching bigrams by weeks. There, the user can follow the evolution of the word king in the corpus. The event detection system does not find any matching event because the user chose to use Web pages as a scale. But pages are timestamped by download date without regard for any historical accuracy.

(5) Now the user switches to the Web fragment level, enters the same query and witnesses that she has the possibility to study Web fragments written up to 2003. The event detection system now understands that around the late 2004 an event concerning the king may have focused the conversations on yabiladi.com. The system identifies it as an official visit of the Morrocan king to Mexico in November 2004. [START_REF] Kahle | Preserving the internet[END_REF] The WAE supports multiple queries (using comma as a separator) for comparison purpose. It displays a coloured line in the n-gram viewer for each query and a union of the resulting fragments in the list below. The user can clearly see a growing percentage of the phrase Ben Ali (the former Tunisian president) during the late 2010 that we may correlate to the beginning of the Arab Spring in Tunisia. This assumption is reinforced by a triggered event about the destitution of Ben Ali in January 2011. [START_REF] Kohlschütter | Boilerplate detection using shallow text features[END_REF] Finally, more seasonal keywords can be entered in the search box such as the muslim month of fasting ramadan. Here the user observes a temporal pattern in the archives that can be explained by the cultural specificity of our Moroccan corpus.

CONCLUSION

In this paper, we proposed an application to reveal historical events. We introduced a new entity called Web fragment to guide researchers through an exploration of Web archives at retrieval time. We described the architecture of our application and, as a demonstration, we witness how the online community of the Moroccan forum yabiladi.com reacted to the Arab Spring at the end of 2010. In the future, we will feed our application with more diverse sets of Web archives (social media streams, blogging platforms, etc.) and work in close collaboration with sociologists and historians to investigate multidisciplinary research questions based on Web archive analysis.

Figure 1 :

 1 Figure 1: Architecture of the Web Archive Explorer (WAE)

https://archive.org/Web/

Publicly available at http://maps.e-diasporas.fr/index.php?focus=map&map=5&section=5

Open source and available at https://github.com/lobbeque/archive-miner and https://github.com/lobbeque/peastee

See http://hadoop.apache.org/, http://spark.apache.org/ and http://lucene.apache-.org/solr/

See the accompanying video https://youtu.be/snW4O-usyTM for a peek at the GUI


Quentin Lobbé
email: quentin.lobbe@telecom-paristech.fr

Ltci

Where the dead blogs are A Disaggregated Exploration of Web Archives to Reveal Extinct Online Collectives

Keywords: web archives, digital heritage, online migrant collectives

The Web is an unsteady environment. As Web sites emerge and expand every days, whole communities may fade away over time by leaving too few or incomplete traces on the living Web. Worldwide volumes of Web archives preserve the history of the Web and reduce the loss of this digital heritage. Web archives remain essential to the comprehension of the lifecycles of extinct online collectives. In this paper, we propose a framework to follow the intern dynamics of vanished Web communities, based on the exploration of corpora of Web archives. To achieve this goal, we define a new unit of analysis called Web fragment: a semantic and syntactic subset of a given Web page, designed to increase historical accuracy. This contribution has practical value for those who conduct large-scale archive exploration (in terms of time range and volume) or are interested in computational approach to Web history and social science. By applying our framework to the Moroccan archives of the e-Diasporas Atlas, we first witness the collapsing of an established community of Moroccan migrant blogs. We show its progressive mutation towards rising social platforms, between 2008 and 2018. Then, we study the sudden creation of an ephemeral collective of forum members gathered by the wave of the Arab Spring in the early 2011. We finally yield new insights into historical Web studies by suggesting the concept of pivot moment of the Web.

Introduction

At the end of the 90's, the development of the Information and Communication Technologies (ICT) reshaped the notion of time, space, and border. The rises of Internet, electronic messaging, and mobile phones provided new remote tools of communication and organisation to worldwide migrant collectives. The Web then became an environment favourable to the establishment of online hubs for migrants to connect with each other or to preserve pieces of a scattered collective memory. In 2012, the e-Diasporas Atlas [START_REF] Diminescu | e-Diasporas Atlas. Explorations and Cartography of Diasporas on Digital Networks[END_REF], directed by D. Diminescu, revealed diasporic collectives that organize first and foremost on the Web, as networks of migrant websites, connected to each other through hypertext links. The atlas led to the observation of 10,000 migrant Web sites distributed along 30 diasporic networks (Moroccan, Tunisian, Egyptian, etc.) called e-Diasporas 1 . But facing, month after month, the partial or total disappearance of some of the observed migrant Web sites, it was decided to start archiving them to ensure the preservation of their digital history and to allow forthcoming researche.

Web archiving. Since the creation of the Web in the early 90's [START_REF]CERN: The document that officially put the world wide web into the public domain[END_REF], the loss of the digital content that constitutes the Web itself has been considered a major issue. Started as a volunteer initiative with the creation of Internet Archive [START_REF] Kahle | Preserving the internet[END_REF], Web archiving was gradually assumed by various states. Shortly after the recognition of the Charter on the Preservation of the Digital Heritage by UNESCO [START_REF]UNESCO: Charter on the preservation of digital heritage[END_REF], terabytes of Web pages were saved worldwide by archiving the genesis of the Web. But after 20 years of Web archiving, it must be said that there is an asymmetry between works focused on upstream archive acquisition [START_REF] Masanès | Web Archiving[END_REF] and analysis of existing Web archives corpora [START_REF] Toyoda | Extracting evolution of web communities from a series of web archives[END_REF]. In practice, most national libraries allow limited consultation points with no remote access to their archived corpora. The online portal of the WayBack Machine 2 only provides a restrictive search-by-URL system without any full-text search facility. Existing tools are designed and effective for refining past versions of a known URL, not for proceeding to a large-scale exploration. Thus, related research based on Web archives chooses to manually track a set of URLs [START_REF] Schafer | The "web of pros" in the 1990s: The professional acclimation of the world wide web in france[END_REF] or to focus on the visual aspects of an archived Web page [START_REF] Ben-David | The colors of the national web: visual data analysis of the historical yugoslav web domain[END_REF]. As a new insight, N. Brügger introduces the notion of analytical Web strata [START_REF] Brügger | Website history and the website as an object of study[END_REF]. He then suggests the possibility of building a dynamic system to resize historical studies from an archived Web page to its individual Web elements.

Summary of main contributions. In this paper, we propose a framework based on the exploration of corpora of Web archives, to follow the internal dynamics of extinct online migrant collectives: communities for which too few or incomplete traces remain on the living Web. We hypothesize that their structure is permeable to the impact of exogenous events or shocks. Our aim is to search for correlations between a given political and social context and the topographic evolutions of a vanished community. We will study two online migrant collectives extracted from the Moroccan section of the e-Diasporas Atlas archives 3 : an established blogosphere (Section 4) and an ephemeral group of forum members (Section 5). They both vanished from the Web at some point before 2018. The Moroccan e-Diaspora is a network of 254 Web sites, built on hypertext citations, created or managed by Moroccan migrants or that deal with them, and initially mapped in 2008 (Figure 1). It can be divided in 3 clusters: 1) Institutional Web sites managed by the Moroccan government, 2) Associations and NGOs, 3) The blogosphere edited by citizens. The forum yabiladi.com can be seen as a hub between the 3 clusters, larbi.org is depicted as one of the leading blogs. The whole network was then weekly archived from March 2010 to September 2014: we count 2,683,928 archived pages for yabiladi.com and 78,311 for larbi.org.

We start by introducing, in Section 2, an entity called Web fragment: a new unit to explore archived corpora that results from the segmentation of a Web page. We then discuss the benefits of using it in comparison to existing approaches. We show, in Section 3, the way we can extract and shape Web fragments out of archived Web pages. We then depict the technical implementation of the whole framework. In Section 4, we witness the collapsing of the Moroccan blogosphere. We show its progressive mutation towards rising social platforms, between 2008 and 2018. In Section 5, we study the creation of an ephemeral collective of members of the forum yabiladi.com gathered by the wave of Arab Spring4 . In particular, we show how some old users converged suddenly around the online organisation of the demonstration of February 20th 2011. Finally, we discuss in Section 6 the limitations of Web archives as a source of information and introduce the notion of pivot moment of the Web.

The Web fragment

In the following, we introduce the Web fragment and discuss the benefits of upscaling the historical analysis of Web archives by using the Web fragment instead of the Web page as new unit of exploration.

Definition

Considering the Web page as the basic unit of access to the World Wide Web, built using its own digital writing modalities, and noticing that from the point of view of human perception [START_REF] Michailidou | Visual complexity and aesthetic perception of web pages[END_REF] a Web page is the result of the logical arrangement of distinct semantic components, we define a Web fragment as a semantic and syntactic subset of a given Web page. There is a scale relationship between a Web page and its Web fragments. A Web fragment is a coherent set of textual, visual, audio or animated contents extracted from a Web page. The Web fragment should be comprehensible on its own. Within the same Web page, two fragments cannot overlap, even partially. A Web fragment must go with an associated set of extracted meta contents (an author, a title, an edition date, etc.) and it must also encompass all the writing and sharing elements used for publishing this content on the Web (CMS widgets, integrated text editor, hypertext links, rss feed, etc.).

Upscaling the exploration

Assumptions. Archive file formats5 are basically a collection of crawled HTML pages associated with a download date. In existing Web archive explorer tools (such as the Wayback Machine), the results are stamped by download date. By contrast, a Web fragment is related to an edition date: the date when it was created or published on the living Web. The many difficulties to retrieve edition dates have allready been addressed by [START_REF] Jatowt | Detecting age of page content[END_REF], but the benefits in term of historical accuracy are impressive. From this point, we will anticipate the possibility of extracting Web fragments (see Section 3 for a technical implementation).

Reducing crawl blindness. We call here crawl blindness the action of mistimestamping a change on a page after a crawl. A change can be the creation, the update, or the deletion of all or part of a Web page [START_REF] Cho | The evolution of the web and implications for an incremental crawler[END_REF]. As a proposition, we first call the process of downloading the Web pages {p 1 ,...,p n } of an entire Web site a crawl c i . We then assume that a corpus of Web archives is the result of one or several successive crawls {c 1 ,...,c l }. An archived Web site consists of n Web pages numbered {p 1 ,...,p n }. The time taken for downloading pages is neglected. We call t i (p j ) the download date of page p j during crawl c i . We assume to know the last modified stamp of page p j denoted µ i (p j ) during crawl c i (having

µ i (p j ) ≤ t i (p j )).
Here, we argue that a page p j consists of m Web fragments numbered {f j1 , ..., f jm }. We also assume to know the edition date of each Web fragment φ(f j1 ), ..., φ(f jm ), where c i is a crawl in which f jk exists, so that an edition date will always be more historically accurate than a download date:

∀p j , f jk ∃φ(f jk ) : φ(f jk ) ≤ µ i (p j ) ≤ t i (p j )
Increasing the historical accuracy. We now assume that the first download date of page p j is denoted as min i t i (p j ) and we approximate its creation date by its first edition date min k φ(f jk ). As an experiment, we select the 109,534 archived Web pages of the forum section of yabiladi.com stamped by first download date.

We split them into 422,906 deduplicated Web fragments stamped by edition dates. To be more specific, the remaining Web fragments can be seen as single archived forum messages associated with a publication date. In Figure 2, we compare the temporal distribution of the archived pages stamped by first download dates (red line) versus their corresponding first edition dates (blue line). First of all, we witness a crawl blindness around 2013 (red line): the crawler stopped archiving during many months. This crawl legacy can be attenuated by switching to the edition dates (blue line

Disaggregating web archives

In the following, we will move to the practical implementation of our framework and discuss our method for extracting and framing Web fragments.

Implementation. Our architecture is released under an open-source license 6 and follows a classical implementation model 7 : 1) archives files are grabed by a Java extractor and then uploaded into a Hadoop Distributed File System (HDFS). 2) A Spark pipeline ingests the HDFS and filters the archives. 3) A dedicated library extracts the Web fragments out of the archived pages. 4) Then the text content of each Web fragment is indexed into a Solr search engine.

Extraction of Web fragments. Here, we consider an archived Web page as a finite set of m HTML nodes {n 1 , ..., n m }, organized as a DOM tree t and associated with some CSS style rules. First, we clean t using the boilerplate method of [START_REF] Kohlschütter | Boilerplate detection using shallow text features[END_REF] to filter out ads and navigation nodes. We then follow user-centric scraping strategies 8 : Mozilla's Readability and Fathom projects. As Readability was designed to find the most important part of a Web page (like an article), we extend it using the Fathom agglomerative clustering algorithm to find all the coherent clusters of HTML nodes. In the Fathom algorithm, all the HTML nodes are initially stored in an m × m sparse adjacency matrix called A. An agglomerative clustering is then applied node by node, having the rows of A incrementally going from single nodes to clusters of nodes. A pseudo-code implementation of it is given in Algorithm 1. We call d the distance function resulting of the depth difference between two nodes in the DOM tree t. We assume the existence of a function named closestRows that returns the two closest rows of A based on the distance between their respective nodes. each Web site after human validation. For each remaining cluster, we parse the HTML and CSS class-names of all the constitutive nodes using a set of dedicated regular expressions to identify and extract edition dates. Finally, we index the text contents as well as all the HTML id and class names9 . To sum up, a Web fragment is a coherent cluster of HTML nodes.

while rows(A) > 1 and closestRows(A) < minDist do

{r i , r j } = closestRows(A) newRow = {} for r ∈ rows(A) do if r = r i and r = r j then newRow[r] = min(d(r i , r), d(r j , r)) end end remove(A[r i ]) remove(A[r j ]) remove(A[ * ][r i ]) remove(A[ * ][r j ]) append(A, newRow) end Algorithm 1: Fathom agglomerative clustering

Archived traces of digital mutation

We now transition to the question of extinct online migrant collectives. In particular, we focus on analysing the collapsing of an old-established community of migrant Moroccan blogs between 2008 and 2018.

An old-established blogosphere. In 2008, a set of 47 blogs (linked together by hypertext citations and created or managed by Moroccan migrants) was discovered and mapped as illustrated by Figure 1 (full network) and 3 (close up, left). The political blog larbi.org possessed the highest in-degree 10 and occupied a central position in the community. The 47 blogs used French as a main language and produced a bundle of political thoughts and daily moods. In 2015, a report [START_REF] Khouzaimi | e-diasporas : Réalisation et interprétation du corpus marocain[END_REF] induced that many of the blogs were no longer active. By updating this survey in 2018, we show that 20 blogs are now dead, 22 have not been updated since at least 2 years and only 5 are still alive (see Figure 3, right).

Exploration task. We emit two hypotheses: 1) the authors of the blogs deleted them and moved away from the Web, 2) the authors migrated from one Web territory to another (such as Twitter or Facebook). As we know that Facebook groups where contemporary of this set of blogs [START_REF] Marchandise | Le facebook des étudiants marocains. territoire relationnel et territoire des possibles[END_REF], we define our task of exploration as finding the past traces of a digital mutation. We choose to target the first traces of social media in the whole archives. In our framework, we request for fragments containing HTML nodes related to social networks like , <button class="Fb-share"></button>, or directly mentioning facebook, youtube, pinterest, etc inside their textual contents.

larbi.org 7didane.org 7didane.org larbi.org The recomposition of the community. The results consist in a filtered set of Web fragments timestamped and grouped by blogs. Some of them contain the URL or the account name of a linked social media. We use the WayBack Machine to visually validate each URL and deliver a qualitative analysis 11 . After managing a blog of their own, 20 authors moved to a social platform: 8 have a Facebook standalone page, 16 are on Twitter (Figure 3). Created between 2005 and 2007, the blogs slowly died around the early 2010's. Keeping alive its digital identity is a shared characteristic in this community, as all the authors reused their pseudonyms (or a close variation of them) on the social media. The online expression is now fragmented and specialized by type of medium. Some choose to have both a Facebook and a Twitter account like 7didane.org. Others use Youtube or Flicker to upload videos and photos like larbi.org. We can observe the dual-use of Twitter alongside Medium, where one writes a long piece of text on Medium and chooses to promote it by using Twitter like eatbees.com. We show that, focusing on the authors that moved on Twitter, the density of the graph of follower/following is higher than the density of the old corresponding citations graph: it goes from 0.16 in 2008 to 0.24 in 2018. The community aspect of the old blogosphere is conserved and even increased.

Followed by the readers. In Figure 3 (right), the size of each social node is correlated to the size of their community of followers or friends. For instance 7didane.org is followed by 43,512 people on Twitter and has 141,947 friends on Facebook. In the new age of social platform, the influence of an author is usually linked with the volume of readers he can communicate with. So the internal dynamics of the blogosphere changed as well: larbi.org grew down as 7didane.org rised up. We show that the diasporic characteristic of the community is conserved. Authors still speak from the outside of Morocco to both Moroccan residents and migrants. We use the netvizz app 12 to extract the country of origin of the followers of each Facebook page. As an example, lailalalami.com still speaks to Morrocan (24%), American (15%) and Pakistani folks (8%). In the case of a crowd-engaging medium like blogs, when a strong connection is created between an author and its readers, they may want to preserve this relation during the process of digital mutation. So, we assume that readers conserved their pseudonyms on Twitter to follow the authors they supported. As an experiment, we request for Web fragments following the template of a comment on larbi.org: a user name, a date and a text contents. We then extract the pseudonyms of 4177 past readers of larbi.org and compare them to its actual followers on Twitter. This results in a lower bound of 647 persistent readers that followed the author. They also represented a significant part of the past audience of the blog, as they wrote 26% of all the archived comments.

The Arab Spring as a key moment. Only 6 blogs wrote a clear farewell message before dying. But the author of 7didane.org indicated that they discovered Twitter by following the 2009 protests in Iran 13 . We also notice that larbi.org first publicly mentioned Twitter by the end of 2010 during the Arab Spring and pointed out its use as a tool to organized citizens actions for the upcoming protest of February 20th, 2011 with the hash-tag #20Fev 14 . It's hard to say out of those too few examples that political mobilisations caused the mutation of blogs into social media. But we can reasonably say that the Arab Spring may have been a key moment for the authors to discover the democratic possibilities of those social platforms.

An ephemeral protest collective

The Arab Spring was in many ways influenced by an active use of social media as a mean for collective organisation [START_REF] Salmon | 29 jours de révolution[END_REF]. In Morocco, the protests occurred early https://apps.facebook.com/netvizz/ The message: https://frama.link/DUo84Yhx, Iran protests: https://frama.link/nZmQD_Y1 https://frama.link/-Gd44Pq3 in 2011 and culminated on February 20th, 2011 when over 10.000 Moroccans demonstrated to demand democratic reforms 15 . So, we now emit the hypothesis of a community of forum members of yabiladi.com gathered around the events of the February 20th.

A hub for Moroccan migrants. Figure 1 illustrates the key role of yabiladi.com as an old-established place in the Moroccan e-Diasporas. Created in the late 2001, the site appeared to spread multi-support informations and to be a meeting places for the migrants living abroad. In 2002, yabiladi.com opened a forum section, organised in categories and threads. The conversations, there, were characterized as a mix between reactions to Moroccan and international actualities and daily life considerations: cooking, family, religion, etc.

Features of the exploration. We define our task of exploration as finding inside the archives of yabiladi.com a community of users who wrote at least one message in a thread related to the February 20th. Thus, we request for Web fragments following the given ordered template: 1) a user name 2) a publication date 3) a text content. They also have to be associated to an URL containing the path "/forum/". Then, we can group the fragments by category and thread, as their pattern of URL follows "/forum/thread_title-category_id-thread_id.html".

We assume the remaining Web fragments to be only composed of archived forum posts. We restrict our space of exploration to the two categories: General and Moroccan and Worldwide Actuality. Revealing a collective. We start by querying our system for a set of thread titles matching the French keywords: "#20Fev", "20 fevrier", etc. We manually validate 12 threads out of them, whether they directly deal with the organisation of the protest or react afterwards to it. We call V 0 this initial group of 12 threads, consisting of 196 messages written by a set of 94 unique users named E 0 . We then select all the threads where at least 2 users of E 0 wrote a message. This new group of 343 threads is called V 1 and we can now define the graph G = (V 1 , E 0 ) as a network of threads linked by co-contributors 16 . With Figure 4, we visualize G on a timeline (in abscissas). Red dots refer to the threads V 1 stamped by the date of their first contribution and sized by numbers of posts. Black links represent the users E 0 writing messages from one thread to another. The vertical position of each thread (in ordinate) is a fixed and arbitrary value chosen to clarify the reading of this visualisation. We find in Figure 4 a specific moment (label #1) where the threads of G are very densely distributed. Between January and February 2011, 25% of V 1 were created. This indicates that the protest of February 20th aggregated an old established community of users that were already using the forum. We see that the pre-protest part of G (before label #1) represents a wide and sparse subgraph spread over a long period of time (from the early 2004 to 2011). In fact 62% of E 0 users wrote their first message during the pre-protest, and in particular 20% of E 0 registered to yabiladi.com in 2007-2008 following a huge wave of new members. They suddenly aggregate each other around label #1 and subsequent fixation points (labels #2 and #3) of the post-protest part of G. We know that the remaining 38% of E 0 contributed first and foremost to label #1 and to the rest of the post-protest threads. To sum up, we have two different patterns: 1) old established users converging as a group by the time of label #1, 2) new members arriving directly on yabiladi.com to contribute to the conversation of label #1 and taking part to the post-protest debates. But both parts similarly and suddenly disappeared in the early 2012.

Refine the results. To better understand the dynamics of convergence around the protest of February 20th, we refine our comprehension of G by conducting a clustering analysis out of it using the modularity class method [START_REF] Blondel | Fast unfolding of communities in large networks[END_REF]. The 8 resulting clusters of threads

Implication for historical web studies

The development of our framework was guided by the idea that a Web site should become the object of historical studies [START_REF] Brügger | Website history and the website as an object of study[END_REF].But here, we may have reached the limits of Web archive corpora by missing a major aspect of our problematic: Web archives are intrinsically incomplete. Mostly created and designed during the early 2000's [START_REF] Masanès | Web Archiving[END_REF], Web archiving systems followed the subsequent evolutions of the Web as a medium but still fail to convey the Web as an ecosystem. The living Web is a flow of informations where various actors are organically interrelated. By contrast, the archived Web is a fixed set of discrete snapshots where records are stored apart from each other. While we were looking at the archived consequences of the Arab Spring, Web actors were already moving away from forums and blogs. The problem of extinct online collective, is less a question of disappearance than a question of transition and Web archives corpora only witness the first leap of what we call a pivot moment of the Web.

Pivot moment of the Web. In the same way as the long history of writing that was punctuated by key moments (oral to written expression, invention of printing, etc), the Web already possesses its own micro-history. We call pivot moment of the Web a period of transition between two systems, a moment when new Web uses fork from established habits and create gaps. A pivot moment arise from 3 factors: (1) the convergence at a specific time (2) between a technological leap and (3) some users sieving it. This leads the Web in new directions of development such as during the democratization of DSL in the late 1990's, the advent of smartphones and mobile Web in the 2010's or the transition from the Web 2.0 to the Web of social network as illustrated in Section 4 and 5.

Conclusion

In this paper, we proposed a framework to follow the internal dynamics of extinct online communities and conduct large scale Web archives exploration. We introduced an entity called Web fragment: a semantic and syntactic subset of a given archived Web page. By applying this framework to the Moroccan Web archives of the e-Diasporas Atlas, we studied the interactions between online groups, exogenous historical events and technological leap on the archived Web.

In the continuity of this analysis, we will support further researches to improve the Web fragment and its multiple uses as a unit of exploration. At the border between computer sciences and digital sociology, our work opens promising questions in terms of historical Web studies. In particular, it would be interesting to consider corpora of Web archives as records of a past ecosystem. We should address the question of mutations and transitions of Web uses regarding nearby pivot moments.

Figure 1 :Figure 2 :

 12 Figure 1: The Moroccan e-Diasporas (mapped by D. Diminescu, M. Renault and M.Jacomy)

Figure 3 :

 3 Figure 3: Evolution of the Moroccan blogosphere between 2008 (left) and 2018 (right) with a kept position

Figure 4 :

 4 Figure 4: Time distribution of yabiladi.com's threads related to the February 20th

  ). Then, as archived pages keep the traces of past messages, we can extend the comprehension of our corpus (archived since 2010) to consider contents written up to 2003 (blue line). If we calculate the difference min

	k	φ(f jk ) in days, the corresponding quartiles are: Q1)
	256, Q2) 777, Q3) 1340. With our framework, doing an exploration on top of
	Web fragments stamped by edition dates will always be more historically accu-
	rate than looking at the original Web pages stamped by download dates.

i t i (p j ) -min

  The variable minDist is the minimal distance to allow for agglomerate two nodes. As a contribution, we extend the distance function d of Readability with visual-based penalties introduced by[START_REF] Cai | Vips: a vision-based page segmentation algorithm[END_REF] and tag-based penalties introduced by[START_REF] Jatowt | Detecting age of page content[END_REF] to handle the "human perception" part of the Web fragment. In practice, we initialize the variable minDist for

	https://github.com/lobbeque/archive-miner and https://github.com/lobbeque/archive-search
	Using Hadoop (http://hadoop.apache.org/), Spark (https://spark.apache.org/) and Solr
	(http://lucene.apache.org/solr/)
	https://github.com/mozilla/readability and https://github.com/mozilla/fathom

  17 can be interpreted as subsequent moments of the evolution of G. Cluster #1 deals with internal debates about the functioning of the forum. Cluster #2 and #3 bundle daily-life considerations. Then Cluster #4 focus on thoughts about the Moroccan identity and comparisons between Morocco and other Maghreb countries. Suddenly, Cluster #5 witnesses the rise of a majority of threads related to the protest of February 20th after having questioned the legitimacy of the Moroccan monarchy. Cluster #6 aggregates post-protest messages. Cluster #7 deals with the political legacy of the protest, by debating about the new Moroccan constitution announced in March 2011. And finally, Cluster #8 goes back to daily life conversations. To sum up, this exploration indicates that the protest was not really prepared online. A sudden spark fired a minor part of yabiladi.com: 94 active users out of a total of 30,564. This wave aggregated old-established members and new comers by breaking daily talks habits. The mobilization did not last in time and stopped with the reform of the Moroccan constitution. Out of the 94 users of E 0 , we find that at least 26 of them created a Twitter account using the same user names18 .

http://www.e-diasporas.fr/ https://archive.org/web/ Available at http://www.e-diasporas.fr/wp/moroccan.html

The Arab Spring was a revolutionary wave of protests in North Africa and the Middle East between 2010 and 2012 (https://en.wikipedia.org/wiki/Arab_Spring)

WARC (Web ARChive) or DAFF (Digital Archive File Format) file formats

See https://github.com/lobbeque/rivelaine for the whole implementation and https://frama.link/XYj1FNSY for the set of regular expressions

The results can be download here https://frama.link/FP-T6Z8_

#1 #2 #3

https://en.wikipedia.org/wiki/Moroccan_constitutional_referendum,_2011

Downloadable results V 1 : https://frama.link/_eModem_, E 0 : https://frama.link/hcxacx89 Downloadable results (as a GEXF graph file) G: https://frama.link/BZdU8CW8 Manually counted and validated in April 2018


Samuel Alizon

Inexpensive research in the golden open access era

Keywords: open access, peer review, funding, publishing, journals, megajournals

The financial pressure that publishers impose on libraries is a worldwide concern. Gold open access publishing with an expensive article processing charge paid by the authors is often presented as an ideal solution to this problem. However, such a system threatens less funded departments and even article quality.

The financial pressure that publishers impose on institutional libraries is a worldwide concern, which has led to increasing support for open access publishing [1]. Gold open access (terms in bold are in the Glossary) with an article processing charge (APC) paid by the authors is often presented as an ideal compromise: publishers can still charge high publication fees, while everyone can access the literature for free without delay. As recent history illustrates, this system is dangerous for theoretical evolutionary ecologists, and, more generally, for researchers working in fields with low funding.

In May 2017, three students and I submitted a manuscript on modelling ebola virulence evolution to a new society journal run by a well-established publisher. This research project had been conducted independently of any specific grant. The journal being open-access-only, we were asked to confirm that we would pay more than 2,000e upon acceptance. This will appear as a negligible fee to some but by French standards at least it is not (besides grant money flagged for specific projects, my colleagues and I's research allowance is 4,000e, and this is more than in most French ecology & evolution departments). We therefore declined the offer and received an automatic email informing us that the publisher had asked the editorial office to withdraw our manuscript. In the end, I contacted the chief editor who informed me he never got to see the submission and we submitted the article elsewhere [2]. Ironically, I had already reviewed 3 manuscripts for this new journal.

Correspondence: samuel.alizon@cnrs.fr Laboratoire MIVEGEC (UMR 5290 CNRS, IRD, UM), 911, avenue Agropolis, BP 64501, 34394 Montpellier, France Full list of author information is available at the end of the article

Publishing costs are dropping

With the advent of online publishing, costs have dropped considerably, as supported by some indicators. At one extreme, the bioRxiv repository costs less then 10$ per preprint [3]. It does not include any typesetting or reviewing, but it does check for plagiarism and offers a Digital Object Identifier (DOI), a built-in search engine and links to social media. This explains why some open access journals can run without APCs and why predatory journals proliferate. The transparency of the non-profit publisher Public Library of Science (PLoS) can also be used to estimate publication costs. In 2016, PLoS declared 43 million USD in expenses and published more than 27,000 open access articles [4]. However, the resulting 1500$ per article most likely overestimates the true publishing cost since PLoS' budget includes questionable expenses such as 'lobbying' or shocking salaries (830,216$ for their two CEOs in 2013) [5]. The numbers in Table 1, which mostly originate from a 2009 report [6], suggest that the cost per paper is likely to be lower than 900$ per article. Importantly, two thirds of this cost correspond to editing and proofreading; two steps that are increasingly neglected in many journals and becoming less time-consuming with new softwares.

Even with our most conservative estimates, publishing costs should have dropped significantly over the last two decades. Instead, we are witnessing the opposite, and open access plays a pivotal role in this illogical trend.

The open access excuse

That anyone can access top level scientific publications is commendable. However, this is currently being used as an excuse to maintain, if not increase, profits from publishing. If the goal is to disseminate research, green open access is almost equally efficient. One of the sole limitations is that journals typically impose a 6 to 12 months embargo [1]. Regardless, nowadays it only takes an email to an author to (legally) obtain a copy of an article. Cynically speaking, the reason why many new journals are open-access-only is probably that publishers have realised they will soon be unable to sell their journals and therefore wish to see the money up front.

At first glance, this issue can appear as a mere budget problem: institutions should shift some funding from libraries to research grants. But the problem is more acute. Indeed, the generalisation of expensive APCs implies that research performed in the absence of grants cannot be published in relevant journals. According to the Directory of Open Access, most open access journals do not charge any APC at all, but unfortunately the articles they publish are marginal, at least in ecology and evolution. In fact, more 'influential' journals tend to have significantly higher APCs [7]. This is worrying because it supports the logic according to which an expensive article is a good one, when the APC is by no means an honest signal.

It is already problematic that for-profit corporations own so many prestigious journals. However, one of the hallmarks of serious journals has always been the symbolic wall separating the editorial board's decision from the publisher's interests. High APCs breach this wall by giving publishers the power to reject an article for financial reasons. Indirectly, they also give funding bodies the power to decide which research is legitimate.

Quantity against quality

In a broader context, the economic model where authors bear all the APC is ethically dangerous because it de facto creates an alignment of interests between a publishing company that wishes to maximise its profits and an author who wants a longer publication list. Far from being criticised, this model has prospered: since 2006 most publishers have followed PLoS ONE's example and launched their own megajournal. These have in common a light reviewing process to ensure that the research is sound and high acceptance rates (typically greater than 50% [8]). The justification for this model is usually the hypothesis that post-publication reviewing will eventually sort out the important and relevant articles. More pragmatically, megajournals are extremely profitable to publishers and their articles are often put on the same standards as that of regular journals. Expensive open-access-publishing by society journals is therefore problematic because it further blurs the line between preprints and rigorously peerreviewed articles.

In 2010, molecular biologist Laurent Ségalat wrote on the analogy between the publication and the financial systems [9]. His worry was that the 'publication frenzy' and the global competition for very limited slots in high impact factor journal might lead to a disaster comparable to the 2008 financial crisis because in both cases short-term gains drive the whole system, a happy few become increasingly rich (or published) and there is little oversight. A few years later, the logic he was criticizing, that is publishing as goal in itself, is more prevalent than ever and high APCs are making things even worse by bringing large amounts of money into the interaction between researchers and publishers.

Towards quality articles with low APC

In their 2017 call for Open Science and Bibliodiversity, the stakeholders of Open Access scientific publishing insisted that costs should neither be paid by the readers nor by the authors and that 'many fair funding models exist' such as institutional support or open archives [10]. Ensuring low APCs will not solve all problems, starting with how articles are selected. But it will at least avoid biasing publications in favour of wealthy fields or departments. It will also avoid having money becoming central in the interaction between authors and journals.

The remaining worry is the rigorous peer-review step. Without it, publications will be read based on authors' reputation or social media coverage. In passing, it is ironic that the key step to justify high APCs is the one that usually costs publishers nothing. Given the increase in the number of submitted manuscripts and the shortage of reviewers, we need to make good reviewing work more rewarding and useful. This is for instance the goal of 'Peer Community in' (PCI), a nonprofit initiative introduced by evolutionary biologists. Following a rigorous reviewing process, preprints recommended by PCI become valid references and can be considered of high value without the need for publication in classical journals (although the authors can still submit the preprint and the decision elsewhere). The whole process is free of charges and the website freely accessible [11].

Research institutions are also aware of the issue. In 2015, it was estimated that all the subscriptions paid by libraries worldwide amounted to 5,000e per article in the Web of Science [12]. This is probably what led the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust in 2012 to launch eLife, a high-level journal, independently of existing publishers. Unfortunately, in 2017 eLife switched to a system with an APC of 2500$ [START_REF] Elife | Setting a fee for publication[END_REF], more than half of which supports marketing, editorials & podcasts and even paying the editors and reviewers (33% of eLife's 'publishing costs' in 2015). This is better than paying for PLoS' CEOs but it does feel strange to ask the authors of accepted articles to pay the editors and reviewers for their 'service'. Surely large public research institutions can come up with a fairer offer.

Help could also come from learned societies. A significant difficulty is that some earn a lot of money from journals edited by publishers. There is a debate to open but, isn't it more ethical to ask society members to pay for the society's activities (via conferences or membership fees)? Furthermore, since publishers are no philantropists, running their journals themselves might even be quite profitable to these societies. This option was not possible before, but with the decreasing costs of online only publishing it should be explored.

Initiatives such as bioRxiv and PCI demonstrate that technological advances from the last decades make it possible to make high-quality peer-reviewed publications from all researchers accessible to all with moderate, or even without, APC. Failure to do so will mean the victory of those for whom the processing charge of an article matters more than its contents.

Glossary

Acceptance rate Proportion of submitted articles that are accepted by a journal. It correlates with many features of the journal [8]. Article Processing Charge (APC) Publication fee charged to the author by the publisher. It is usually higher for open access articles because, in theory, the publisher should decrease subscription costs. Digital Object Identifier (DOI) Unique and persistent identifier divided in two parts (the first part refers to the registrant, the second to the object). A consortium of publishers (CrossRef) centralises it for journals and books. Green Open Access Self-archiving from the author of the peer-reviewed (often non-typesetted) version of an article. Although not all journals allow for it [14], some countries permit it for most publications after a delay (e.g. 6 or 12 months in France). Gold Open Access The final typesetted version of the article is made available free of charge to the reader and usually with a high APC to the author. Megajournal open-access-only journal with a light reviewing process that is typically multi-disciplinary and with high acceptance rates (typically greater than 50%). Open-access-only Publishing mode that consists in only publishing online open access articles. Predatory journals Journal with a near 100% acceptance rate and high APCs given the service provided. Preprint Unreviewed manuscript posted online, often on dedicated servers such as arXiv, bioRxiv, or HAL.

Table 1 Estimations of per article publishing costs for printed or online-only open access articles. Unless specified otherwise, the expense categories and the estimates originate from Hougton et al.'s report [6]. Their estimates were very conservative in 2009 and costs are likely to have dropped since. Here, we removed the 20% cost for Management and investment and the 20% cost for profits. Furthermore, the bioRxiv cost for online hosting was used [3]. The peer-reviewing cost is only shown for illustrative purposes and is not included in the calculations.

Expense category

Acknowledgements

I thank the CNRS and the IRD for their support and Denis Bourguet, Nacho Bravo, Sébastien Lion, Carmen Lía Murall and Wolf Blanckenhorn for their suggestions.