{"id":819,"date":"2010-05-05T00:12:56","date_gmt":"2010-05-05T07:12:56","guid":{"rendered":"https:\/\/dubinko.info\/blog\/?p=819"},"modified":"2010-05-05T00:12:56","modified_gmt":"2010-05-05T07:12:56","slug":"geek-thoughts-no-fly-lists-and-cap-theorem","status":"publish","type":"post","link":"https:\/\/dubinko.info\/blog\/2010\/05\/geek-thoughts-no-fly-lists-and-cap-theorem\/","title":{"rendered":"Geek Thoughts: no-fly lists and CAP Theorem"},"content":{"rendered":"<p>According to <a href=\"http:\/\/www.nytimes.com\/2010\/05\/05\/nyregion\/05plane.html\">this<\/a> article, a recent terror suspect almost got on a plane despite being recently added to the no-fly list. Why is it so difficult to administer a no-fly list? The <a href=\"http:\/\/www.julianbrowne.com\/article\/viewer\/brewers-cap-theorem\">CAP Theorem<\/a> has answers. (Disclaimer: as always, this blog is apolitical&#8211;this isn&#8217;t about whether no-fly lists are a good idea or not, only a matter of technical interest)<\/p>\n<p>Without stretching the imagination too much, one can think of a no-fly list as a distributed database. The list apparently changes frequently, and it needs to be accessible from thousands of airport gates and reservation desks. Thus CAP Theorem applies. In a nutshell, that theorem states that of Consistency, Availability, and Partition-tolerance, you can only pick, at most, two. Hit the link above for a much better, more complete description.<\/p>\n<p>If there was one centralized list, the system would be Consistent and Available, but every time a name needed to be checked it would require an immediate network round-trip&#8211;should the connection to that central list go down, no further checks would be possible&#8211;no Partition tolerance.<\/p>\n<p>Of course, the airline could set a policy that if said network connection goes down, no passengers at all would be able to get on planes. This would be a case of lack of Availability.<\/p>\n<p>Or, the complete list could be periodically copied to each location that needs it. This provides good Availability and Partition tolerance, but fails Consistency, since it&#8217;s possible to miss out on late-breaking updates. Apparently, something like this is what happened.<\/p>\n<p>More collected Geek Thoughts at http:\/\/<a href=\"http:\/\/geekthoughts.info\/\">geekthoughts<\/a>.info.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>According to this article, a recent terror suspect almost got on a plane despite being recently added to the no-fly list. Why is it so difficult to administer a no-fly list? The CAP Theorem has answers. (Disclaimer: as always, this blog is apolitical&#8211;this isn&#8217;t about whether no-fly lists are a good idea or not, only&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[284,22],"tags":[971,804,820,1179,972],"class_list":["post-819","post","type-post","status-publish","format-standard","hentry","category-geekthoughts","category-software","tag-cap-theorem","tag-database","tag-distributed","tag-geekthoughts","tag-nosql"],"aioseo_notices":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8eo8l-dd","_links":{"self":[{"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/posts\/819","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/comments?post=819"}],"version-history":[{"count":2,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/posts\/819\/revisions"}],"predecessor-version":[{"id":821,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/posts\/819\/revisions\/821"}],"wp:attachment":[{"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/media?parent=819"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/categories?post=819"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dubinko.info\/blog\/wp-json\/wp\/v2\/tags?post=819"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}