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COMET in Plone


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COMET is an upcoming method for delivering real-time interaction to a website by using server-push technologies. At the Snow Sprint 2008 Jean-Nicolas Bes and Ramon Bartl worked on making COMET work for the Open Source CMS Plone.

This is their presentation from the final sprint summary.

Published in: Technology
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COMET in Plone

  1. 1. Bringing Comet to Plone KSS + Eventpush A first quick and dirty approach dr_jnut & ramonski
  2. 2. • „Comet is a giant Hack“ - Jacob Rus • use mechanisms unforseen by browser Vendors and unspecified by web standards
  3. 3. Traditional Web Applications • Page-by-page web • Pages load on user request • No real time
  4. 4. AJAX Web Application • Updating parts of the page with JS • Closes each connection after a response is served • No real time
  5. 5. Ajax with polling • Browser polls regulary the server for updates. • Wastes server resources and bandwith. • No real real time • Trade-off between latency and server load
  6. 6. Comet Web Application • Sending data to the client without explicit request • Rely on persistent connection between server and client • REAL real time!!!
  7. 7. 2 Strategies • Streaming - Single persistent connection • Long Polling - New request for each event - No response until an event occurs
  8. 8. „Forever Frame“ IFrame streaming approach • Gradually filled with script tags to be executed in the browser • Rendered incrementally, so each script tag is executed as it is received. • Can grow to an unreasonable size...
  9. 9. eventPush ClientSide HttpWizard Zope/Plone HTTP proxy eventPush iFrame /@@feeder
  10. 10. HttpWizard internals Proxy (rewrites URI) VirtualHost Backend Frontend eventPush VirtualHost
  11. 11. eventPush fileupload ClientSide HttpWizard Zope/Plone Upload iframe HTTP proxy eventPush iFrame /@@feeder
  12. 12. File upload in HttpWizard FileUpload hook 4. 3. 4. Proxy 2. (rewrites URI) 5. VirtualHost 1. Backend Frontend eventPush VirtualHost
  13. 13. DEMO Time
  14. 14. How will this evolve? • HTML 5 draft from WHATWG * • Introduces server-sent events • Much more straightforward • Avoids comet downsides * Web Hypertext Application Technology Working Group
  15. 15. Links • • Buildout: plonekss/eventPush/buildout/trunk
  16. 16. Thanks to... • KSS guys (__gotcha, ree et al.) • Lovely systems • Berggasthof Piz-Buin • idSoftware (Q3 Rocketarena) • beer in all variants