This looks great, well done Tika!
Thank you for sharing, Tim
Cheers
Stefan
On 2017-07-05, Allison, Timothy B. wrote:
> Fellow file-philes on [compress],
> Sebastian Nagel has added file type id via Apache Tika to Common Crawl.
> While Tika is not 100% accurate, this means that we have far better clarity
> on mime type than relying on the http header+file suffix. So, for testing
> purposes, you (or we over on Tika) can much more easily gather a small test
> corpus of files by mime type.
> Many, many thanks to Sebastian and Common Crawl!
> Cheers,
> Tim
> -----Original Message-----
> From: Sebastian Nagel [mailto:wastl.na...@googlemail.com]
> Sent: Tuesday, July 4, 2017 6:18 AM
> To: u...@tika.apache.org
> Subject: Tika content detection and crawled "remote" content
> Hi,
> recently I've plugged in Tika's content detection into Common Crawl's crawler
> (modified Nutch) with the target to get clean and correct MIME type - the
> HTTP Content-Type may contain garbage and isn't always correct [1].
> For the June 2017 crawl I've prepared a comparison of content types sent by
> the server in the HTTP header and as detected by Tika 1.15 [2]. It shows
> that content types by Tika are definitely clean
> (1,400 different content types vs. more than 6,000 content type "strings"
> from HTTP headers).
> A look on the "confusions" where Content-Type and Tika differ, shows a mixed
> picture: some pairs are plausible, e.g., if Tika changes the type to a more
> precise subtype or detects the MIME at all:
> Tika-1.15 HTTP-Content-Type
> 1001968023 application/xhtml+xml text/html
> 2298146 application/rss+xml text/xml
> 617435 application/rss+xml application/xml
> 613525 text/html unk
> 361525 application/xhtml+xml unk
> 297707 application/rdf+xml application/xml
> However, there are a few dubious decisions, esp. the group of web server-side
> scripting languages (ASP, JSP, PHP, ColdFusion, etc.):
> Tika-1.15 HTTP-Content-Type
> 2047739 text/x-php text/html
> 681629 text/asp text/html
> 193095 text/x-coldfusion text/html
> 172318 text/aspdotnet text/html
> 139033 text/x-jsp text/html
> 38415 text/x-cgi text/html
> 32092 text/x-php text/xml
> 18021 text/x-perl text/html
> Of course, due to misconfigurations some servers may deliver the script files
> unmodified but in general I wouldn't expect that this happens for millions of
> pages. I've checked some of the affected URLs:
> - HTML fragment (no declaration of <!DOCTYPE...> or <html> opening tag)
> https://www.projectmanagement.com/profile/profile_contributions.cfm?profileID=46773580&popup=&c_b=0&c_mb=0&c_q=0&c_a=2&c_r=1&c_bc=1&c_wc=0&c_we=0&c_ar=0&c_ack=0&c_v=0&c_d=0&c_ra=2&c_p=0
> http://www.privi.com/product-details.asp?cno=C10910011
> http://mental-ray.de/Root_alt/Default.asp
> http://ekyrs.org/support/index.php?action=profile
> http://cwmorse.eu5.org/lineal/mostrar.php?contador=200
> - (overlong) comment block at start of HTML which "masks" the HTML declaration
> http://www.mannheim-virtuell.de/index.php?branchenID=2&rubrikID=24
> http://www.exoduschurch.org/bbs/view.php?id=sunday_school&page=1&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=6
>
> https://www.preventiongenetics.com/About/Resources/disease/MarfansSyndrome.php
> https://de.e-stories.org/categories.php?&lan=nl&art=p
> - HTML with some scripting fragments ("<?php?>") present:
> http://www.eco-ani-yao.org/shien/
> - others are clearly HTML (looks more like a bug, at least, there is no
> simple explanation)
> http://www.proedinc.com/customer/content.aspx?redid=9
>
> http://cball.dyndns.org/wbb2/board.php?boardid=8&sid=bf3b7971faa23413fa1164be0c068f79
> http://eusoma.org/Engx/Info/ContactUs.aspx?cont=contact
> http://cball.dyndns.org/wbb2/map.php?sid=bf3b7971faa23413fa1164be0c068f79
> Obviously certain file suffixes (.php, .aspx) should get less weight compared
> to Content-Type sent from the responding server.
> Now my question: where's the best place to fix this: in the crawler [3] or in
> Tika?
> If anyone is interested in using the detected MIME types or anything else
> from Common Crawl - I'm happy to help! The URL index [4] contains now a new
> field "mime-detected" which makes it easy to search or grep for confusion
> pairs.
> Thanks and best,
> Sebastian
> [1] https://github.com/commoncrawl/nutch/issues/3
> [2]
> s3://commoncrawl-dev/tika-content-type-detection/content-type-diff-tika-1.15-cc-main-2017-26.txt.xz
> https://commoncrawl-dev.s3.amazonaws.com/tika-content-type-detection/content-type-diff-tika-1.15-cc-main-2017-26.txt.xz
> [3]
> https://github.com/apache/nutch/blob/master/src/java/org/apache/nutch/util/MimeUtil.java#L152
> [4] http://commoncrawl.org/2015/04/announcing-the-common-crawl-index/
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