COMET in Plone

Slide 1: Bringing Comet to Plone KSS + Eventpush A first quick and dirty approach dr_jnut & ramonski http://plone.org

Slide 2: • „Comet is a giant Hack“ - Jacob Rus • use mechanisms unforseen by browser Vendors and unspecified by web standards

Slide 3: Traditional Web Applications • Page-by-page web • Pages load on user request • No real time

Slide 4: AJAX Web Application • Updating parts of the page with JS • Closes each connection after a response is served • No real time

Slide 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

Slide 6: Comet Web Application • Sending data to the client without explicit request • Rely on persistent connection between server and client • REAL real time!!!

Slide 7: 2 Strategies • Streaming - Single persistent connection • Long Polling - New request for each event - No response until an event occurs

Slide 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...

Slide 9: eventPush ClientSide HttpWizard Zope/Plone HTTP proxy eventPush iFrame /@@feeder

Slide 10: HttpWizard internals Proxy (rewrites URI) VirtualHost www.plone.org Backend Frontend eventPush VirtualHost www.plone.net

Slide 11: eventPush fileupload ClientSide HttpWizard Zope/Plone Upload iframe HTTP proxy eventPush iFrame /@@feeder

Slide 12: File upload in HttpWizard FileUpload hook 4. 3. 4. Proxy 2. (rewrites URI) 5. VirtualHost 1. www.plone.org Backend Frontend eventPush VirtualHost www.plone.net

Slide 13: DEMO Time

Slide 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

Slide 15: Links • http://plone.org • Buildout: https://svn.plone.org/svn/collective/ plonekss/eventPush/buildout/trunk

Slide 16: Thanks to... • KSS guys (__gotcha, ree et al.) • Lovely systems • Berggasthof Piz-Buin • idSoftware (Q3 Rocketarena) • beer in all variants