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Introduction to Restful Web Services
- 1. Introduction to RESTful Web Services 09/2012 Wei Li
- 2. Agenda • RESTful in General • URI Design • Java Implementation • Others • Test • Demonstration
- 4. In a Nutshell • RESTful is about resources • RESTful is about how to represent the resource in different ways • RESTful is about how to manipulate the resource
- 5. Define REST • REST stands for Representational State Transfer • An architecture style for designing networked applications
- 6. Define REST • REST offers a simple, interoperable, and flexible way of writing web services that can be very different than the RPC mechanisms like CORBA and WS-*
- 7. RESTful Is Not • A protocol • A standard • A replacement for SOAP
- 8. RESTful Architectural Principles • Addressable resources • A uniform, constrained interface • Representation oriented • Stateless communicate • Hypermedia As The Engine Of Application State (HATEOAS)
- 9. Resources • The key abstraction of information and data in REST • Each resource must be addressable via a URI (Uniform Resource Identifier) • Everything can be a resource
- 10. Addressability • Every object and resource in the system should be reachable through a unique identifier • Managed through the use of URIs
- 11. Uniform and Constrained Interface • Don’t have an “action” parameter in URI • Use only the methods of HTTP for the web services • HTTP has a small fixed set of operational methods. Each method has a specific purpose and meaning
- 12. Representation Oriented • The user interacts with services using representations of that service • A resource referenced by one URI can have different formats. – HTML (for browsers) – XML (for application) – JSON (for JavaScript) – Excel spreadsheet – Image
- 13. Stateless Communication • No client session data stored on the server • If there are needs for session-specific data, it should be held and maintained by the client and transferred to the server with each request as needed • A service layer that does not have to maintain client sessions is much easier to scale
- 14. RESTful and HTTP • REST isn't protocol specific • However when talking about REST, people usually mean REST over HTTP • Benefits of using HTTP for RESTful services: Familiarity Interoperability Interoperability
- 15. REST Triangle Source: http://en.wikipedia.org/wiki/File:Resttriangle.svg
- 16. HTTP Methods • GET • PUT • DELETE • POST • HEAD • OPTIONS
- 17. CRUD Operation Mapped to HTTP Methods in RESTful OPERATION HTTP METHOD Create POST Read GET Update PUT Delete DELETE
- 18. HTTP Response Code • 200 OK • 201 Created • 202 Accepted • 204 Success • 301 Moved Permanently • 302 Found • 303 See Other • 304 Not Modified • 500 Internal Error • 503 Service Unavailable
- 19. HTTP Response Code • 401 Unauthorized • 403 Forbidden • 404 Not Found • 405 Method Not Allowed • 409 Conflict • 411 Length Required • 413 Entity Too Long • 415 Unsupported Media Type
- 20. Create a Resource Source: Rest in Practice
- 21. Read a Resource Source: Rest in Practice
- 22. Update a Resource Source: Rest in Practice
- 23. Delete a Resource Source: Rest in Practice
- 24. URI Design
- 25. URI • Human meaningful • Hierarchical • Nouns • No verbs
- 26. URI Examples • http://localhost:9999/restapi/books – GET – get all books – POST – add a new book • http://localhost:9999/restapi/books/{id} – GET – get book whose id is provided – PUT – update the book whose id is provided – DELETE – delete the book whose is provided
- 27. URI Examples • Twitter REST API v1.1 example: – https://dev.twitter.com/docs/api/1.1
- 29. Content Negotiation and URI • http://localhost:9999/restapi/books/{id}.xml • http://localhost:9999/restapi/books/{id}.json • http://localhost:9999/restapi/books/{id}.pdf
- 30. Content Negotiation and URI • https://cwiki.apache.org/WINK/jax-rs- content-negotiation.html
- 32. JSR-311 • POJO based • HTTP centric • Format independence • Container independence • Inclusion in Java EE
- 35. Available Java Frameworks • Jersey • CXF • Wink • RESTEasy
- 36. Others
- 37. WADL • The Web Application Description Language • A machine-readable XML description of HTTP-based web applications (typically RESTful web services).
- 38. WADL • Example (using Jersey implementation) http://localhost:9999/restapi/application.wadl
- 39. Versioning • Put the version in URI http://localhost:9999/restapi/v2.0/books
- 40. Versioning • put the version in the Accept Header of the request http://stackoverflow.com/questions/389169/ best-practices-for-api- versioning/6750376#6750376
- 41. Security • HTTPS (encrypt channel) • Web ACL • Others (more advanced)
- 42. Error Handling • Use standard error message format as response • Use Non-200 response codes HTTP/1.1 400 Bad Request Content-Type: application/xml;charset=UTF-8 Link: http://server/error/someexplanation <error> <message>You have made an invalid request... </message> </error>
- 43. Demonstration • A simple one page web application http://mybooks.cloudfoundry.com/books.html • Restful web service is implemented using Jersey • Client consumes the service through JQUERY AJAX API and render the JSON data
- 44. Test
- 45. Test RESTful Web Services • Using cURL
- 46. Test RESTful Web Services • Using cURL
- 47. Test RESTful Web Services • Using cURL
- 48. Test RESTful Web Services • Using SOAPUI
- 49. Test RESTful Web Services • Using SOAPUI
- 50. Test RESTful Web Services • Using SOAPUI
- 51. Test RESTful Web Services • Using SOAPUI
- 52. Test RESTful Web Services • Using SOAPUI
- 53. Reference • http://www.ics.uci.edu/~fielding/pubs/ dissertation/top.htm
- 54. Books