Understanding and Using Rest APIs presented at SocialDevCamp Chicago 2009.

1. REST 11.07.2009 Understanding and Using RESTful APIs

3. Bulk of experience on enterprise-scale applications

4. Microsoft platform (mostly)

6. Using REST

8. REST Overview APIs based on the Representational State Transfer (REST) architecture dominate web 2.0 mash-up and social media development. There are a number of frameworks available that support the development of RESTful APIs (WCF, JAX-RS, Wicket, Zend) We are still missing an established mechanism for documentation and discovery and client-side tool support for rapid implementation.

9. REST Overview REST-style architectures consist of clients and servers. Requests and responses are built around the transfer of "representations" of "resources". A resource is any entity that can be addressed in a URI (an account, an employee, a physical file) A representation of a resource is any information that captures the current or intended state of a resource. All information necessary to process and complete a request is contained within it.

10. Example Resource (Twitter Public Timeline) http://twitter.com/statuses/public_timeline.xml Resource (Twitter User) http://twitter.com/users/petermorano.xml

11. REST Overview REST-style architectures consist of clients and servers. Requests and responses are built around the transfer of "representations" of "resources". A resource is any entity that can be addressed in a URI (an account, an employee, a physical file) A representation of a resource is any information that captures the current or intended state of a resource. All information necessary to process and complete a request is contained within it.

12. Wait a Minute If this sounds a lot like the Web, it’s because the Web is a REST implementation Roy Fielding, who created REST, was also one of the principal authors of HTTP

14. Be Stateless and Cacheable

15. Use Addressable Resources

17. Be Stateless and Cacheable

18. Use Addressable Resources

20. URI Examples GET http://www.example.com/v1/employees GET http://www.example.com/v1/employees/1824 POST http://www.example.com/v1/employees PUT http://www.example.com/v1/employees/1513 DELETE http://www.example.com/v1/employees/1222

22. Be Stateless and Cacheable

23. Use Addressable Resources

25. Every HTTP request executes in complete isolation on the server

27. Be Stateless and Cacheable

28. Use Addressable Resources

30. Anything you can point to

32. Be Stateless and Cacheable

33. Addressable Resources

35. Resources are modifiable through Representations

36. XML

37. JSON

39. REST Cons Must be HTTP No Atomic Transactions No Standards for security except HTTPS No Standardized Discovery

40. REST vs. SOAP Unlike SOAP-based web services, there is no "official" standard for RESTful web service. Though not a standard, a RESTful implementation uses standards like HTTP, URL, XML, GIF, etc.

42. Verbose Payload

43. Envelope

44. Not easily readable

45. Requires Development Tools

46. Uses POST Method

47. Supports Transactions

48. Standardized Discovery

50. Lightweight Payload

51. Postcard

52. Human Readable Results

53. Easy to work with, Brower-testable

54. GET Method supports caching

55. No Transactions

56. Discovery

59. Format the URI (parameters, variables)

60. Encode Authentication into the Header

61. Make Call

63. Community-built library/wrapper

64. code.google.com

65. www.codeplex.com

67. You may be waiting for the library to become available.

70. Eclipse Http4e

71. Fiddler

73. WADL Web Application Discovery Language (WADL) Created in 2005 by Marc Hadley of Sun Microsystems Submitted to W3C on 8/31/2009 REST’s Answer to WSDL Specification: https://wadl.dev.java.net/

74. What WADL Gets You Reduced Errors in Discovery Opportunities for Code Generation Spend more time building your application and less time implementing APIs

75. So Where Is It? Currently in Submission to W3C API Providers are slow to adopt, so tool providers are slow to implement There are projects underway to generate code from WADL, and at least one tool that helps in creating WADL

76. WADL Demo Project on code.google.com Online Version: http://tomayac.de/rest-describe/latest/RestDescribe.html

77. References http://en.wikipedia.org/wiki/Representational_State_Transfer http://weblogs.java.net/blog/mhadley/archive/2005/05/introducing_wad.html http://blog.tomayac.de/index.php?date=2007-05-23 RESTful Web Services – Richardson, Ruby – O’Reilly Press