REST in peace @ Osidays 2011 India 11-21-2011
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The document discusses REST and HTTP caching. It explains the key principles of REST including client-server architecture, statelessness, cacheability, layered system, and uniform interface. It then discusses how to implement caching and scalability in HTTP, including using expiration headers, cache-control headers, and entity tags to control caching. It notes the importance of caching for performance, scalability, and reducing workload.
![Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],
Bengaluru, 20-22 November 2011](https://image.slidesharecdn.com/restinpeaceosidays2011-111121093818-phpapp02/85/REST-in-peace-Osidays-2011-India-11-21-2011-100-320.jpg)
![Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],
Bengaluru, 20-22 November 2011](https://image.slidesharecdn.com/restinpeaceosidays2011-111121093818-phpapp02/85/REST-in-peace-Osidays-2011-India-11-21-2011-101-320.jpg)
![Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],
Bengaluru, 20-22 November 2011](https://image.slidesharecdn.com/restinpeaceosidays2011-111121093818-phpapp02/85/REST-in-peace-Osidays-2011-India-11-21-2011-102-320.jpg)
![Default headers
Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',
Cache-Control = 'no-cache, must-revalidate',
ETag = $_SERVER['REQUEST_TIME'],
Bengaluru, 20-22 November 2011](https://image.slidesharecdn.com/restinpeaceosidays2011-111121093818-phpapp02/85/REST-in-peace-Osidays-2011-India-11-21-2011-103-320.jpg)
REST in peace @ Osidays 2011 India 11-21-2011
- 1. RESTin peace Bengaluru, 20-22 November 2011
- 2. Sorry for the ugly slide. There will be others. Really sorry. Bengaluru, 20-22 November 2011
- 3. REST in a nutshell Bengaluru, 20-22 November 2011
- 4. 2000 Fielding's dissertation: REpresentational State Transfer http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm Bengaluru, 20-22 November 2011
- 5. REST in a nutshell: 1. Client <> Server Bengaluru, 20-22 November 2011
- 6. REST in a nutshell: 2. Stateless Bengaluru, 20-22 November 2011
- 7. Servers do not keep any informations the clients uses during different requests. Bengaluru, 20-22 November 2011
- 8. So the architecture scales well. Bengaluru, 20-22 November 2011
- 9. REST in a nutshell: 3. Cacheable Bengaluru, 20-22 November 2011
- 10. Client has access to resources stored between it and the origin server. Bengaluru, 20-22 November 2011
- 11. So communication is faster. Bengaluru, 20-22 November 2011
- 12. REST in a nutshell: 4. Layered system Bengaluru, 20-22 November 2011
- 13. Intermediary nodes can be used along our architecture. Bengaluru, 20-22 November 2011
- 14. So you efficiently implement point 3. Bengaluru, 20-22 November 2011
- 15. REST in a nutshell: 5. Uniform interface Bengaluru, 20-22 November 2011
- 16. Communicate using well-known verbs and providing all the informations needed to consume a service. Bengaluru, 20-22 November 2011
- 17. So fallbacks are easy. Bengaluru, 20-22 November 2011
- 18. this was a bit difficult to understand so, obviously... Bengaluru, 20-22 November 2011
- 19. nobody had a clue Bengaluru, 20-22 November 2011
- 20. ANTIPATTERNS Bengaluru, 20-22 November 2011
- 21. 1 URIs Bengaluru, 20-22 November 2011
- 22. "REST is about cool URI design" http://apple.com/users/1/licenses/4.json Bengaluru, 20-22 November 2011
- 23. "REST is about cool URI design" http://apple.com/users/1/licenses/4.json Bengaluru, 20-22 November 2011
- 24. http://apple.com/site/en_US/showUsers.jsp?uid=1&license=4 is OK too Bengaluru, 20-22 November 2011
- 25. but, enter simple rule of thumb Bengaluru, 20-22 November 2011
- 26. cool URIs help you think in term of resources - David Zuelke Bengaluru, 20-22 November 2011
- 27. 2 URIs (bis) Bengaluru, 20-22 November 2011
- 28. REST follows a URI schema GET /users POST /users PUT /users/{id} DELETE /users/{id} ... Bengaluru, 20-22 November 2011
- 29. REST follows a URI schema GET /users POST /users PUT /users/{id} DELETE /users/{id} ... Bengaluru, 20-22 November 2011
- 30. what if you change your URL? Bengaluru, 20-22 November 2011
- 31. client is broken Bengaluru, 20-22 November 2011
- 32. RESTful clients should be driven by service's hypermedia controls Roy Fielding : http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven Bengaluru, 20-22 November 2011
- 33. HATEOAS Bengaluru, 20-22 November 2011
- 34. 3 POST is cool Bengaluru, 20-22 November 2011
- 35. said SOAP 1.1 Bengaluru, 20-22 November 2011
- 36. said SOAP 1.1 Bengaluru, 20-22 November 2011
- 37. loosing meaningful verbs at the protocol level Bengaluru, 20-22 November 2011
- 38. loosing meaningful verbs at the protocol level nothing cacheable by default Bengaluru, 20-22 November 2011
- 39. loosing meaningful verbs at the protocol level nothing cacheable by default what about bookmarking? Bengaluru, 20-22 November 2011
- 40. 4 500 is your friend Bengaluru, 20-22 November 2011
- 41. said SOAP ( again ) Bengaluru, 20-22 November 2011
- 42. GET /users/300 Host: www.example.com Bengaluru, 20-22 November 2011
- 43. GET /users/300 Host: www.example.com HTTP/1.1 500 Internal Server Error Etag: 1234 X-Powered-By: php/5.3 ... The record cannot be found Bengaluru, 20-22 November 2011
- 44. GET /users/300 Host: www.example.com HTTP/1.1 500 Internal Server Error Etag: 1234 X-Powered-By: php/5.3 ... The record cannot be found Bengaluru, 20-22 November 2011
- 45. The HTTP protocol is awesome, and lets you return meaningful and universally-understood status codes Bengaluru, 20-22 November 2011
- 46. 404 Not Found Bengaluru, 20-22 November 2011
- 47. 404 Not Found OMG Link is broken? Bengaluru, 20-22 November 2011
- 48. 202 Accepted Bengaluru, 20-22 November 2011
- 49. 202 Accepted You get an immediate OK, and the operation will hopefully complete Bengaluru, 20-22 November 2011
- 50. Pause Bengaluru, 20-22 November 2011
- 51. The WWW Bengaluru, 20-22 November 2011
- 52. the largest data-exchange network on the planet Bengaluru, 20-22 November 2011
- 53. And meanwhile, at Facebook... 12TB of new data every day (1 year ago) 500 million users Bengaluru, 20-22 November 2011
- 54. And meanwhile, at Google... 1 billion unique monthly googlers Bengaluru, 20-22 November 2011
- 55. via HTTP , baby! Bengaluru, 20-22 November 2011
- 56. HTTP in a nutshell: 1. Client <> Server Bengaluru, 20-22 November 2011
- 57. HTTP in a nutshell: 2. Stateless Bengaluru, 20-22 November 2011
- 58. HTTP in a nutshell: 3. widespread cache spec http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html Bengaluru, 20-22 November 2011
- 59. HTTP in a nutshell: Lao Tze Song using Firefox 6 Company proxy Great chinese (fire)wall Reverse proxy Origin server 4. Layered system Bengaluru, 20-22 November 2011
- 60. HTTP in a nutshell: 5. it is the uniform interface between clients and servers Bengaluru, 20-22 November 2011
- 61. HTTP bleeds REST Bengaluru, 20-22 November 2011
- 62. How do I implement this goodness? Bengaluru, 20-22 November 2011
- 63. 1. caching & scalability Bengaluru, 20-22 November 2011
- 64. HTTP cache Bengaluru, 20-22 November 2011
- 65. Types of cache Local Shared/proxy Shared/reverse proxy Bengaluru, 20-22 November 2011
- 66. Types of cache Local Shared/proxy Shared/reverse proxy Bengaluru, 20-22 November 2011
- 67. Bengaluru, 20-22 November 2011
- 68. Types of cache Local Shared/proxy Shared/reverse proxy Bengaluru, 20-22 November 2011
- 69. Bengaluru, 20-22 November 2011
- 70. Types of cache Local Shared/proxy Shared/reverse proxy Bengaluru, 20-22 November 2011
- 71. Bengaluru, 20-22 November 2011
- 72. on the server side Bengaluru, 20-22 November 2011
- 73. Caching with Expiration (example) Bengaluru, 20-22 November 2011
- 74. HTTP/1.1 200 OK Host: www.example.com Expires: 0 Bengaluru, 20-22 November 2011
- 75. HTTP/1.1 200 OK Host: www.example.com Expires: 0 Bengaluru, 20-22 November 2011
- 76. HTTP/1.1 200 OK Host: www.example.com Expires: Tue, 31 Jan 2011 01:00 GMT Bengaluru, 20-22 November 2011
- 77. HTTP/1.1 200 OK Host: www.example.com Cache-Control: max-age=60, public Bengaluru, 20-22 November 2011
- 78. HTTP/1.1 200 OK Host: www.example.com Cache-Control: max-age=60, public Bengaluru, 20-22 November 2011
- 79. HTTP/1.1 200 OK Host: www.example.com Cache-Control: max-age=60, public Cacheable for 60 seconds Bengaluru, 20-22 November 2011
- 80. HTTP/1.1 200 OK Host: www.example.com Cache-Control: max-age=60, public Cacheable by both local and shared caches Bengaluru, 20-22 November 2011
- 81. You can also cache with validation (Etags, If-None-Match, ...) Bengaluru, 20-22 November 2011
- 82. Why HTTP caching is so important? Bengaluru, 20-22 November 2011
- 83. Ask yourself: as a developer, what do I want on my application? Bengaluru, 20-22 November 2011
- 84. Evolve Loose coupling Work less Bengaluru, 20-22 November 2011
- 85. Evolve Because you want your platform to extensible Loose coupling Work less Bengaluru, 20-22 November 2011
- 86. Evolve Because you want your platform to extensible Loose coupling Because you want it to be easy to integrate with, evolve, plug and mantain Work less Bengaluru, 20-22 November 2011
- 87. Evolve Because you want your platform to extensible Loose coupling Because you want it to be easy to integrate with, evolve, plug and mantain Work less Because every LoC is bug-prone and our man-day is a hard-to- scale cost Bengaluru, 20-22 November 2011
- 88. enters our Hero #1 Bengaluru, 20-22 November 2011
- 89. Bengaluru, 20-22 November 2011
- 90. Bengaluru, 20-22 November 2011
- 91. enters our Hero #2 Bengaluru, 20-22 November 2011
- 92. Bengaluru, 20-22 November 2011
- 93. http://www.lullabot.com/articles/a-beginners-guide-to-caching-data Bengaluru, 20-22 November 2011
- 94. 2007 Bengaluru, 20-22 November 2011
- 95. 2011? Bengaluru, 20-22 November 2011
- 96. it supports HTTP caching! http://drupal.org/node/147310 Bengaluru, 20-22 November 2011
- 97. it supports HTTP caching! http://drupal.org/node/147310 ( people is supposed to clap their hands here ) Bengaluru, 20-22 November 2011
- 98. but Bengaluru, 20-22 November 2011
- 99. wait.... how? Bengaluru, 20-22 November 2011
- 100. Default headers Expires = 'Sun, 19 Nov 1978 05:00:00 GMT', Cache-Control = 'no-cache, must-revalidate', ETag = $_SERVER['REQUEST_TIME'], Bengaluru, 20-22 November 2011
- 101. Default headers Expires = 'Sun, 19 Nov 1978 05:00:00 GMT', Cache-Control = 'no-cache, must-revalidate', ETag = $_SERVER['REQUEST_TIME'], Bengaluru, 20-22 November 2011
- 102. Default headers Expires = 'Sun, 19 Nov 1978 05:00:00 GMT', Cache-Control = 'no-cache, must-revalidate', ETag = $_SERVER['REQUEST_TIME'], Bengaluru, 20-22 November 2011
- 103. Default headers Expires = 'Sun, 19 Nov 1978 05:00:00 GMT', Cache-Control = 'no-cache, must-revalidate', ETag = $_SERVER['REQUEST_TIME'], Bengaluru, 20-22 November 2011
- 104. is that even legal? Bengaluru, 20-22 November 2011
- 105. "but you can redefine them!" Bengaluru, 20-22 November 2011
- 106. drupal_add_http_header() Bengaluru, 20-22 November 2011
- 107. function drupal_add_http_header() { ... ... drupal_send_headers($headers); } Bengaluru, 20-22 November 2011
- 108. so, what drupal_send_headers() can do so evil? Bengaluru, 20-22 November 2011
- 109. header() , of course Bengaluru, 20-22 November 2011
- 110. which means Bengaluru, 20-22 November 2011
- 111. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', 'I'm not'); var_dump(headers_list()); Bengaluru, 20-22 November 2011
- 112. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', 'I'm not'); var_dump(headers_list()); array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dump-Header: I'm not' Bengaluru, 20-22 November 2011
- 113. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', false); var_dump(headers_list()); Bengaluru, 20-22 November 2011
- 114. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', false); var_dump(headers_list()); array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dump-Header: I'm batman' Bengaluru, 20-22 November 2011
- 115. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', ' '); var_dump(headers_list()); Bengaluru, 20-22 November 2011
- 116. drupal_add_http_header('Dumb-Header', 'I'm batman!'); ... // other logic ... drupal_add_http_header('Dumb-Header', ' '); var_dump(headers_list()); array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dumb-Header:' Bengaluru, 20-22 November 2011
- 117. or Bengaluru, 20-22 November 2011
- 118. you can use header_remove() ( PHP 5.3 ) Bengaluru, 20-22 November 2011
- 119. and create a new class to manage/keep track of headers and caching directives Bengaluru, 20-22 November 2011
- 120. but we're lazy and we don't want to reinvent the wheel Bengaluru, 20-22 November 2011
- 121. Goals Work less evolve loose coupling Bengaluru, 20-22 November 2011
- 122. Goals Work less evolve loose coupling Bengaluru, 20-22 November 2011
- 123. everything is done for us! :) but.... Bengaluru, 20-22 November 2011
- 124. tmp files, cache tables, procedural code... mmmmh.... gotta be something better Bengaluru, 20-22 November 2011
- 125. Frameworks Bengaluru, 20-22 November 2011
- 126. Bengaluru, 20-22 November 2011
- 127. ONE Bengaluru, 20-22 November 2011
- 128. Cache is used for compiling routes, autoloading, ... Bengaluru, 20-22 November 2011
- 129. Cache is used for compiling routes, autoloading, ... ...but also for storing the view Bengaluru, 20-22 November 2011
- 130. Goals Work less evolve loose coupling Bengaluru, 20-22 November 2011
- 131. Goals Work less evolve loose coupling Bengaluru, 20-22 November 2011
- 132. at least because we use a framework Bengaluru, 20-22 November 2011
- 133. HTTP
- 134. Less work Bengaluru, 20-22 November 2011
- 135. http://www.flickr.com/photos/snakphotography/5004775320/sizes/o/in/photostream/ because the hard work is delegated to the browser/proxy Bengaluru, 20-22 November 2011
- 136. Evolve Bengaluru, 20-22 November 2011
- 137. because cache is abstracted from the application Bengaluru, 20-22 November 2011
- 138. Loose coupling Bengaluru, 20-22 November 2011
- 139. because caching is bound to the protocol, HTTP, not to your implementation ( Sf, RoR, Django ) Bengaluru, 20-22 November 2011
- 140. but hey, you say Bengaluru, 20-22 November 2011
- 141. HTTP's cache fails when dealing with really dynamic pages, because consumers will always have to hit the origin server, although a part of the page would be cacheable ( header and footer, for example ) Bengaluru, 20-22 November 2011
- 142. Nope Nope Bengaluru, 20-22 November 2011
- 143. ESI was built for that http://www.w3.org/TR/esi-lang Bengaluru, 20-22 November 2011
- 144. Edge Side Includes A de facto standard for bla bla bla... Bengaluru, 20-22 November 2011
- 145. Edge Side Includes A de facto standard for bla bla bla... Server side includes ( not SSI! ) usually handled by the architecture's ESI processor. http://www.w3.org/TR/esi-lang http://www.w3.org/TR/edge-arch
- 146. <esi:include src="http://osidays.com/talks/1" /> Bengaluru, 20-22 November 2011
- 147. <esi:include src="http://osidays.com/talks/1" /> Bengaluru, 20-22 November 2011
- 148. <esi:include src="http://osidays.com/talks/1" /> Bengaluru, 20-22 November 2011
- 149. 1s (tweets) 3600 (post) Bengaluru, 20-22 November 2011
- 150. <esi:include src='tweets.html' /> <esi:include src='article/12.html' /> Bengaluru, 20-22 November 2011
- 151. 2. adaptability & durability Bengaluru, 20-22 November 2011
- 152. Hypermedia another long-time friend Bengaluru, 20-22 November 2011
- 153. Links outrageously semplifying Bengaluru, 20-22 November 2011
- 154. <img src="..." /> <a href="..." /> <link rel="payment" ... /> Bengaluru, 20-22 November 2011
- 155. <img src="..." /> <a href="..." /> <link rel="payment" ... /> Bengaluru, 20-22 November 2011
- 156. <img src="..." /> <a href="..." /> <link rel="payment" ... /> Bengaluru, 20-22 November 2011
- 157. <link rel="payment" href="/checkout" type="text/html" ... /> Bengaluru, 20-22 November 2011
- 158. <link rel="payment" href="/checkout" type="text/html" ... /> Bengaluru, 20-22 November 2011
- 159. <link rel="payment" href="/checkout" type="text/html" ... /> Bengaluru, 20-22 November 2011
- 160. <link rel="payment" href="/checkout" type="text/html" ... /> Bengaluru, 20-22 November 2011
- 161. POST /users Host: www.example. com HTTP/1.1 201 Created Host: www.example.com Etag: 1234 X-Powered-By: php/5.3 Location: /users/1 Bengaluru, 20-22 November 2011
- 162. POST /users Host: www.example. com HTTP/1.1 201 Created Host: www.example.com Etag: 1234 X-Powered-By: php/5.3 Location: /users/1 Bengaluru, 20-22 November 2011
- 163. POST /users Host: www.example. com HTTP/1.1 201 Created Host: www.example.com Etag: 1234 X-Powered-By: php/5.3 Location: /new-users-db/1 Bengaluru, 20-22 November 2011
- 164. POST /users Host: www.example. com HTTP/1.1 201 Created Host: www.example.com Etag: 1234 X-Powered-By: php/5.3 Location: /new-users-db/1 Bengaluru, 20-22 November 2011
- 165. consumers of your API are able to follow the changes of your design Bengaluru, 20-22 November 2011
- 166. Client knows how to consume the service based on the informations auto-provided by the service itself Bengaluru, 20-22 November 2011
- 167. No WSDL. Bengaluru, 20-22 November 2011
- 168. No URI templates. Bengaluru, 20-22 November 2011
- 169. No easily-outdated documentation. Bengaluru, 20-22 November 2011
- 170. No assumptions. Bengaluru, 20-22 November 2011
- 171. Less WTFs. Bengaluru, 20-22 November 2011
- 172. Bengaluru, 20-22 November 2011
- 173. This does not easily break. Bengaluru, 20-22 November 2011
- 174. HATEOAS Hypermedia As The Engine Of Application State Bengaluru, 20-22 November 2011
- 175. 6 Bengaluru, 20-22 November 2011
- 176. everything seems eventually cool Recap: why REST? Bengaluru, 20-22 November 2011
- 177. Pros Performances Bengaluru, 20-22 November 2011
- 178. Pros Scalability Bengaluru, 20-22 November 2011
- 180. Pros Durability Bengaluru, 20-22 November 2011
- 181. Not RESTful? Bengaluru, 20-22 November 2011
- 182. Simply don't care Bengaluru, 20-22 November 2011
- 183. Rules of architectural design Bengaluru, 20-22 November 2011
- 184. Follow them according to your needs Bengaluru, 20-22 November 2011
- 185. amazon.com Bengaluru, 20-22 November 2011
- 186. So... Bengaluru, 20-22 November 2011
- 187. Bengaluru, 20-22 November 2011
- 188. Alessandro Nadalin Bengaluru, 20-22 November 2011
- 189. odino.org Bengaluru, 20-22 November 2011
- 190. Bengaluru, 20-22 November 2011
- 191. @_odino_ #osidays Bengaluru, 20-22 November 2011
- 192. Thank YOU! @_odino_ Bengaluru, 20-22 November 2011
- 193. Credits http://www.flickr.com/photos/larachris/16564077/sizes/o/in/photostream/ http://www.flickr.com/photos/ashatenbroeke/4367373081/sizes/z/in/photostream/ http://www.flickr.com/photos/yourdon/3140270189/sizes/l/in/photostream/ http://www.flickr.com/photos/jox1989/4964706072/sizes/l/in/photostream/ http://www.flickr.com/photos/brainfg/168506259/sizes/o/in/photostream/ http://www.flickr.com/photos/norte_it/3897091546/sizes/o/in/photostream/ http://www.zdnet.com/blog/service-oriented/soap-versus-rest-a-matter-of-style/3568 http://www.flickr.com/photos/turtlemom_nancy/2046347762/sizes/l/in/photostream/ http://www.flickr.com/photos/juanpg/3333385784/sizes/z/in/photostream/ http://www.flickr.com/photos/congvo/301678287/sizes/l/in/photostream/ http://www.flickr.com/photos/ihasb33r/2573196546/sizes/z/in/photostream/ http://www.flickr.com/photos/martin_heigan/4544138976/sizes/o/in/photostream/ http://www.flickr.com/photos/cknara/4195099999/sizes/o/in/photostream/ http://www.flickr.com/photos/1080p/3076529265/sizes/l/in/photostream/ http://www.flickr.com/photos/adamrice/280300202/sizes/l/in/photostream/ http://www.flickr.com/photos/tomer_a/541411897/sizes/o/in/photostream/ http://www.flickr.com/photos/subpra/4514008262/sizes/l/in/photostream/ http://www.flickr.com/photos/lippincott/2539720043/sizes/l/in/photostream/ http://www.flickr.com/photos/rawryder/5086090931/sizes/l/in/photostream/ http://www.flickr.com/photos/robboudon/5312731161/sizes/l/in/photostream/ http://www.flickr.com/photos/bc-burnslibrary/4158243488/sizes/o/in/photostream/ http://www.flickr.com/photos/13606325@N08/2416993706/sizes/o/in/photostream/ http://www.flickr.com/photos/neothezion/5135841069/sizes/l/in/photostream/ http://www.flickr.com/photos/planetschwa/2494067809/ http://www.flickr.com/photos/thomasthomas/258931782/ http://www.flickr.com/photos/rustyboxcars/2629631562/sizes/l/in/photostream/ http://www.flickr.com/photos/ell-r-brown/4138727474/sizes/l/in/photostream/ http://www.flickr.com/photos/noah123/5082076630/sizes/z/in/photostream/ http://www.flickr.com/photos/jungle_boy/220181177/sizes/l/in/photostream/ http://www.flickr.com/photos/prettydaisies/872539081/sizes/l/in/photostream/ http://www.flickr.com/photos/kaptainkobold/76256150/sizes/o/in/photostream/ http://www.flickr.com/photos/uomoincravatta/1438372865/sizes/z/in/photostream/ Bengaluru, 20-22 November 2011